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  • 1.
    Abdel-Baset, T. A.
    et al.
    Taibah Univ, Fac Sci, Dept Phys, Yanbu 46423, Saudi Arabia.;Fayoum Univ, Fac Sci, Dept Phys, Al Fayyum 63514, Egypt..
    Abdel-Hafiez, Mahmoud
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi.
    Effect of metal dopant on structural and magnetic properties of ZnO nanoparticles2021Ingår i: Journal of materials science. Materials in electronics, ISSN 0957-4522, E-ISSN 1573-482X, Vol. 32, nr 12, s. 16153-16165Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Zn1-xRxO (R = Li, Mg, Cr, Mn, Fe and Cd) were obtained by using co-precipitation synthesis technique with constant weight percent of 3% from R ions. The phase composition, crystal structure, morphology, density functional theory (DFT), and magnetic properties were examined to comprehend the influence of Zn2+ partial substitution with R ions. X-ray diffraction shows that the ZnO lattice parameters were slightly affected by R doping and the doped sample crystallinity is enhanced. Our results show that introducing Cr, Mn and Fe along with Mg into ZnO induces a clear magnetic moment without any apparent distortion in the structural morphology. The spatial configuration of dopant atoms is determined from first-principles calculations, giving a better understanding of the position of the dopant atom responsible for the magnetism. The magnetic moments obtained from our calculations are 3.67, 5.0, and 4.33 mu B per dopant atom for Cr, Mn, and Fe, respectively, which agree with the experimental values. While Cr and Fe tend to form clusters, Mn has more propensity to remain evenly distributed within the system, avoiding cluster-derived magnetism.

  • 2.
    Abdelhamid, Hani Nasser
    et al.
    Stockholm Univ, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden;Assiut Univ, Dept Chem, Adv Multifunct Mat Lab, Assiut 71515, Egypt.
    El-Zohry, Ahmed M.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström.
    Cong, Jiayan
    KTH Royal Inst Technol, Dept Chem, Appl Phys Chem, Tekn Ringen 30, S-10044 Stockholm, Sweden.
    Thersleff, Thomas
    Stockholm Univ, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden.
    Karlsson, Martin
    KTH Royal Inst Technol, Dept Chem, Appl Phys Chem, Tekn Ringen 30, S-10044 Stockholm, Sweden.
    Kloo, Lars
    KTH Royal Inst Technol, Dept Chem, Appl Phys Chem, Tekn Ringen 30, S-10044 Stockholm, Sweden.
    Zou, Xiaodong
    Stockholm Univ, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden.
    Towards implementing hierarchical porous zeolitic imidazolate frameworks in dye-sensitized solar cells2019Ingår i: Royal Society Open Science, E-ISSN 2054-5703, Vol. 6, nr 7, artikel-id 190723Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A one-pot method for encapsulation of dye, which can be applied for dye-sensitized solar cells (DSSCs), and synthesis of hierarchical porous zeolitic imidazolate frameworks (ZIF-8), is reported. The size of the encapsulated dye tunes the mesoporosity and surface area of ZIF-8. The mesopore size, Langmuir surface area and pore volume are 15 nm, 960-1500 m(2). g(-1) and 0.36-0.61 cm(3). g(-1), respectively. After encapsulation into ZIF-8, the dyes show longer emission lifetimes (greater than 4-8-fold) as compared to the corresponding non-encapsulated dyes, due to suppression of aggregation, and torsional motions.

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  • 3.
    Abdelhamid, Hani Nasser
    et al.
    Stockholm Univ, Dept Mat & Environm Chem, Berzelii Ctr EXSELENT Porous Mat, SE-10691 Stockholm, Sweden;Assiut Univ, Dept Chem, Assiut 71515, Egypt.
    Wilk-Kozubek, Magdalena
    Stockholm Univ, Dept Mat & Environm Chem, Berzelii Ctr EXSELENT Porous Mat, SE-10691 Stockholm, Sweden;PORT Polish Ctr Technol Dev, Dept Nanotechnol, 147 Stablowicka St, PL-54066 Wroclaw, Poland.
    El-Zohry, Ahmed
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Gomez, Antonio Bermejo
    Stockholm Univ, Dept Organ Chem, SE-10691 Stockholm, Sweden.
    Valiente, Alejandro
    Stockholm Univ, Dept Organ Chem, SE-10691 Stockholm, Sweden.
    Martin-Matute, Belen
    Stockholm Univ, Dept Organ Chem, SE-10691 Stockholm, Sweden.
    Mudring, Anja-Verena
    Stockholm Univ, Dept Mat & Environm Chem, Berzelii Ctr EXSELENT Porous Mat, SE-10691 Stockholm, Sweden.
    Zou, Xiaodong
    Stockholm Univ, Dept Mat & Environm Chem, Berzelii Ctr EXSELENT Porous Mat, SE-10691 Stockholm, Sweden.
    Luminescence properties of a family of lanthanide metal-organic frameworks2019Ingår i: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 279, s. 400-406Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Two isostructural series of lanthanide metal-organic frameworks denoted as SUMOF-7II (Ln) and SUMOF-7IIB (Ln) (Ln = La, Ce, Pr, Nd, Sm, Eu, and Gd) were synthesized using4,4',4 ''-(pyridine-2,4,6-triyl)tris(benzoic acid) (H(3)L2) and a mixture of H(3)L2 and 4,4',4 ''-(benzene-1,3,5-triyl)tris(benzoic acid) (H3BTB) as linkers, respectively. Both series were characterized using powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), thermal analysis (TGA), and photoluminescence spectroscopy. Photoluminescence measurements show that Eu-MOFs demonstrate a red emission while Pr- and Nd-MOFs display an emission in the near-infrared (NIR) range. On the other hand, La-, Ce-, Sm- and Gd-MOFs exhibit only a ligand-centered emission. The average luminescence lifetimes in the SUMOF-7IIB series are 1.3-1.4-fold longer than the corresponding ones in the SUMOF-7II series. SUMOF-7IIs show a good photo- and thermal stability. Altogether, the properties of SUMOF-7II and SUMOF-7IIB render them promising materials for applications including sensing, biosensing, and telecommunications.

  • 4.
    Abdelki, Andreas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för materialvetenskap, Nanoteknologi och funktionella material.
    Fused deposition modeling of API-loaded mesoporous magnesium carbonate2020Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In this thesis, the incorporation of drug loaded mesoporous magnesium carbonate as an excipient for the additive manufacturing of oral tablets by fused deposition modeling was investigated. Cinnarizine, a BCS class II drug, was loaded into the pores of the mesoporous material via a soaking method, corresponding to a drug loading of 8.68 wt%. DSC measurements on the loaded material suggested that the drug was partially crystallized after incorporation, meanwhile the XRD diffractogram implied that the drug was in a state lacking long range order. The drug loaded material was combined with two pharmaceutical polymers, Aquasolve LG and Klucel ELF, and extruded into filaments with a single screw extruder. Filaments of Klucel ELF and drug loaded Upsalite (30:70 wt% ratio) were successfully implemented for the printing oral tablets, in contrast to the Aquasolve LG based filaments which were difficult to print due to thickness variations and non-uniform material distributions. The drug content obtained by TGA suggested drug loadings of 7.71 wt% and 2.23 wt% in the drug loaded Upsalite and tablets respectively. Dissolution studies using an USP II apparatus showed a slower API-release from the tablets in comparison to the crystalline drug, most probably due to slow diffusion of drug species through the polymeric matrix. For future studies, pharmaceutical polymers with higher aqueous solubility should be investigated in order to thoroughly examine the potential of utilizing the immediate release property of Upsalite.

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  • 5.
    Abdellah, Mohamed
    et al.
    Lund Univ, Div Chem Phys, Box 124, S-22100 Lund, Sweden.;Lund Univ, NanoLund, Box 124, S-22100 Lund, Sweden.;South Valley Univ, Qena Fac Sci, Dept Chem, Qena 83523, Egypt..
    Poulsen, Felipe
    Univ Copenhagen, Dept Chem, DK-2100 Copenhagen, Denmark..
    Zhu, Qiushi
    Lund Univ, Div Chem Phys, Box 124, S-22100 Lund, Sweden.;Lund Univ, NanoLund, Box 124, S-22100 Lund, Sweden..
    Zhu, Nan
    Tech Univ Denmark, Dept Chem, Kemitorvet Bldg 207, DK-2800 Lyngby, Denmark.;Dalian Univ Technol, Zhang Dayu Sch Chem, Dalian 116024, Peoples R China..
    Zidek, Karel
    Acad Sci Czech Republ, Inst Plasma Phys, Reg Ctr Special Opt & Optoelect Syst TOPTEC, Za Slovankou 1782-3, Prague 18200 8, Czech Republic..
    Chabera, Pavel
    Lund Univ, Div Chem Phys, Box 124, S-22100 Lund, Sweden.;Lund Univ, NanoLund, Box 124, S-22100 Lund, Sweden..
    Corti, Annamaria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Hansen, Thorsten
    Univ Copenhagen, Dept Chem, DK-2100 Copenhagen, Denmark..
    Chi, Qijin
    Tech Univ Denmark, Dept Chem, Kemitorvet Bldg 207, DK-2800 Lyngby, Denmark..
    Canton, Sophie E.
    DESY, Attosecond Sci Grp, Notkestr 85, D-22607 Hamburg, Germany.;ELI HU Nonprofit Ltd, ELI ALPS, Dugonics Ter 13, H-6720 Szeged, Hungary..
    Zheng, Kaibo
    Lund Univ, Div Chem Phys, Box 124, S-22100 Lund, Sweden.;Lund Univ, NanoLund, Box 124, S-22100 Lund, Sweden.;Qatar Univ, Coll Engn, Gas Proc Ctr, POB 2713, Doha, Qatar..
    Pullerits, Tonu
    Lund Univ, Div Chem Phys, Box 124, S-22100 Lund, Sweden.;Lund Univ, NanoLund, Box 124, S-22100 Lund, Sweden..
    Drastic difference between hole and electron injection through the gradient shell of CdxSeyZn1−xS1−y quantum dots2017Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 9, nr 34, s. 12503-12508Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ultrafast fluorescence spectroscopy was used to investigate the hole injection in CdxSeyZn1-xS1-y gradient core-shell quantum dot (CSQD) sensitized p-type NiO photocathodes. A series of CSQDs with a wide range of shell thicknesses was studied. Complementary photoelectrochemical cell measurements were carried out to confirm that the hole injection from the active core through the gradient shell to NiO takes place. The hole injection from the valence band of the QDs to NiO depends much less on the shell thickness when compared to the corresponding electron injection to n-type semiconductor (ZnO). We simulate the charge carrier tunneling through the potential barrier due to the gradient shell by numerically solving the Schrodinger equation. The details of the band alignment determining the potential barrier are obtained from X-ray spectroscopy measurements. The observed drastic differences between the hole and electron injection are consistent with a model where the hole effective mass decreases, while the gradient shell thickness increases.

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  • 6.
    Abdi, Zahra
    et al.
    Inst Adv Studies Basic Sci IASBS, Dept Chem, Zanjan 4513766731, Iran..
    Bagheri, Robabeh
    Soochow Univ, Sch Phys Sci & Technol, Coll Energy, Soochow Inst Energy & Mat Innovat, Suzhou 215006, Peoples R China.;Soochow Univ, Key Lab Adv Carbon Mat & Wearable Energy Technol, Suzhou 215006, Peoples R China..
    Reza Mohammadi, Mohammad
    Univ Sistan & Baluchestan, Dept Phys, Zahedan 9816745845, Iran..
    Song, Zhenlun
    Chinese Acad Sci, Ningbo Inst Mat Technol & Engn, Surface Dept, Surface Protect Res Grp, 519 Zhuangshi Rd, Ningbo 315201, Peoples R China..
    Görlin, Mikaela
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Dau, Holger
    Free Univ Berlin, Fachbereich Phys, Arnimallee 14, D-14195 Berlin, Germany..
    Najafpour, Mohammad Mahdi
    Inst Adv Studies Basic Sci IASBS, Dept Chem, Zanjan 4513766731, Iran..
    In Situ Synthesis of Manganese Oxide as an Oxygen-Evolving Catalyst: A New Strategy2021Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 27, nr 4, s. 1330-1336Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    All studies on oxygen-evolution reaction by Mn oxides in the presence of cerium(IV) ammonium nitrate (CAN) have been so far carried out by synthesizing Mn oxides in the first step. And then, followed by the investigation of the Mn oxides in the presence of oxidants for oxygen-evolution reaction (OER). This paper presents a case study of a new and promising strategy for in situ catalyst synthesis by the adding Mn-II to either CAN or KMnO4/CAN solution, resulting in the formation of Mn-based catalysts for OER. The catalysts were characterized by scanning electron microscopy, energy-dispersive spectroscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray absorption spectroscopy, and X-ray photoelectron spectroscopy. Both compounds contained nano-sized particles that catalyzed OER in the presence of CAN. The turnover frequencies for both catalysts were 0.02 (mmolO2 /mol(Mn).

  • 7. Abdi-Jalebi, Mojtaba
    et al.
    Andaji-Garmaroudi, Zahra
    Cacovich, Stefania
    Stavrakas, Camille
    Philippe, Bertrand
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Richter, Johannes M.
    Alsari, Mejd
    Booker, Edward P.
    Hutter, Eline M.
    Pearson, Andrew J.
    Lilliu, Samuele
    Savenije, Tom J.
    Rensmo, Håkan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Divitini, Giorgio
    Ducati, Caterina
    Friend, Richard H.
    Stranks, Samuel D.
    Maximizing and stabilizing luminescence from halide perovskites with potassium passivation2018Ingår i: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 555, s. 497-501Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Metal halide perovskites are of great interest for various high-performance optoelectronic applications. The ability to tune the perovskite bandgap continuously by modifying the chemical composition opens up applications for perovskites as coloured emitters, in building-integrated photovoltaics, and as components of tandem photovoltaics to increase the power conversion efficiency. Nevertheless, performance is limited by non-radiative losses, with luminescence yields in state-of-the-art perovskite solar cells still far from 100 per cent under standard solar illumination conditions. Furthermore, in mixed halide perovskite systems designed for continuous bandgap tunability2 (bandgaps of approximately 1.7 to 1.9 electronvolts), photoinduced ion segregation leads to bandgap instabilities. Here we demonstrate substantial mitigation of both non-radiative losses and photoinduced ion migration in perovskite films and interfaces by decorating the surfaces and grain boundaries with passivating potassium halide layers. We demonstrate external photoluminescence quantum yields of 66 per cent, which translate to internal yields that exceed 95 per cent. The high luminescence yields are achieved while maintaining high mobilities of more than 40 square centimetres per volt per second, providing the elusive combination of both high luminescence and excellent charge transport. When interfaced with electrodes in a solar cell device stack, the external luminescence yield—a quantity that must be maximized to obtain high efficiency—remains as high as 15 per cent, indicating very clean interfaces. We also demonstrate the inhibition of transient photoinduced ion-migration processes across a wide range of mixed halide perovskite bandgaps in materials that exhibit bandgap instabilities when unpassivated. We validate these results in fully operating solar cells. Our work represents an important advance in the construction of tunable metal halide perovskite films and interfaces that can approach the efficiency limits in tandem solar cells, coloured-light-emitting diodes and other optoelectronic applications.

  • 8.
    Abdi-Jalebi, Mojtaba
    et al.
    Univ Cambridge, Dept Phys, Cavendish Lab, JJ Thomson Ave, Cambridge, England.
    Pazoki, Meysam
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Philippe, Bertrand
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Dar, M. Ibrahim
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photon & Interfaces, Lausanne, Switzerland.
    Alsari, Mejd
    Univ Cambridge, Dept Phys, Cavendish Lab, JJ Thomson Ave, Cambridge, England.
    Sadhanala, Aditya
    Univ Cambridge, Dept Phys, Cavendish Lab, JJ Thomson Ave, Cambridge, England.
    Diyitini, Giorgio
    Univ Cambridge, Dept Mat Sci & Met, Charles Babbage Rd, Cambridge, England.
    Imani, Roghayeh
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Lilliu, Samuele
    Univ Sheffield, Dept Phys & Astron, Sheffield, S Yorkshire, England; UAE Ctr Crystallog, Dubai, U Arab Emirates.
    Kullgren, Jolla
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Rensmo, Håkan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Gratzel, Michael
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photon & Interfaces, Lausanne, Switzerland.
    Friend, Richard H.
    Univ Cambridge, Dept Phys, Cavendish Lab, JJ Thomson Ave, Cambridge, England.
    Dedoping of Lead Halide Perovskites Incorporating Monovalent Cations2018Ingår i: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 12, nr 7, s. 7301-7311Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report significant improvements in the optoelectronic properties of lead halide perovskites with the addition of monovalent ions with ionic radii close to Pb2+. We investigate the chemical distribution and electronic structure of solution processed CH3NH3PbI3 perovskite structures containing Na+, Cu+, and Ag+, which are lower valence metal ions than Pb2+ but have similar ionic radii. Synchrotron X-ray diffraction reveals a pronounced shift in the main perovskite peaks for the monovalent cation-based films, suggesting incorporation of these cations into the perovskite lattice as well as a preferential crystal growth in Ag+ containing perovskite structures. Furthermore, the synchrotron X-ray photoelectron measurements show a significant change in the valence band position for Cu- and Ag-doped films, although the perovskite bandgap remains the same, indicating a shift in the Fermi level position toward the middle of the bandgap. Such a shift infers that incorporation of these monovalent cations dedope the n-type perovskite films when formed without added cations. This dedoping effect leads to cleaner bandgaps as reflected by the lower energetic disorder in the monovalent cation-doped perovskite thin films as compared to pristine films. We also find that in contrast to Ag+ and Cu+, Na+ locates mainly at the grain boundaries and surfaces. Our theoretical calculations confirm the observed shifts in X-ray diffraction peaks and Fermi level as well as absence of intrabandgap states upon energetically favorable doping of perovskite lattice by the monovalent cations. We also model a significant change in the local structure, chemical bonding of metal-halide, and the electronic structure in the doped perovskites. In summary, our work highlights the local chemistry and influence of monovalent cation dopants on crystallization and the electronic structure in the doped perovskite thin films.

  • 9. Abdin, Amir
    et al.
    Feyzabi, Kaveh
    Hellman, Oskar
    Nordström, Henrietta
    Rasa, Dilman
    Thaung Tolförs, Gustav
    Öqvist, Per-Olof
    Methods to create compressive stress in high strength steel components2018Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Residual compressive stresses can be used to increase the lifetime of parts under cyclic stress as they negate the applied tensile stresses that cause crack initiation and propagation in the material. The goal of this project was to investigate methods to induce stresses, their advantages and disadvantages as well as depth and magnitude of induced stresses, and also to find methods of analyzing the induced residual stresses. This was done on behalf of Epiroc Drilling Tools AB in order for them to induce stresses on the insides of their long, narrow and hollow rods, where stress induction is difficult. Shot peening was used as a reference as that is the method currently in use by the company. The results show that the two most promising methods are cavitation peening and laser shock peening; two relatively new methods with large magnitudes and depth of induced stress as well as a great capability of inducing stresses on the hard-to-reach insides of the rods. Ultrasonic needle peening, ultrasonic shot peening as well as induction hardening, cryogenic treatment and friction stir processing were also investigated. Methods of analyzing the stresses include X-ray diffraction and slitting, hole drilling and ultrasonic methods.

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  • 10.
    Abdulla, Beyar
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för materialvetenskap, Nanoteknologi och funktionella material.
    Nanocellulose surface functionalization for in-situ growth of zeolitic imidazolate framework 67 and 82020Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This master’s thesis was conducted at the Department of Nanotechnology and Functional Materials at Ångström Laboratory as part of an on-going project to develop hybrid nanocomposites from Cladophora cellulose and a sub-type of metal-organic frameworks; zeolitic imidazolate frameworks (ZIFs). By utilizing a state-of-the-art interfacial synthesis approach, in-situ growth of ZIF particles on the cellulose could be achieved. TEMPO-mediated oxidation was diligently used to achieve cellulose nanofibers with carboxylate groups on their surfaces. These were ion-exchanged to promote growth of ZIF particles in a nanocellulose solution and lastly, metal ions and organic linkers which the ZIFs are composed of were added to the surface functionalized and ion-exchanged nanocellulose solution to promote ZIF growth. By vacuum filtration, mechanical pressing and furnace drying; freestanding nanopapers were obtained. A core-shell morphology between the nanocellulose and ZIF crystals was desired and by adjusting the metal ion concentration, a change in morphologies was expected. The nanocomposites were investigated with several relevant analytical tools to confirm presence, attachment and in-situ growth of ZIF crystal particles upon the surface of the fine nanocellulose fibers. Both the CNF@ZIF-67 and CNF@ZIF-8 nanocomposites were successfully prepared as nanopapers with superior surface areas and thermal properties compared to pure TEMPO-oxidized cellulose nanopapers. The CNF@ZIFs showcased hierarchical porosities, stemming from the micro- and mesoporous ZIFs and nanocellulose, respectively. Also, it was demonstrated that CNF@ZIF-8 selectively adsorbed CO2 over N2. Partial formation of core-shell structure could be obtained, although a relationship between increased metal ions and ZIF particle morphology could not wholly be observed.

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  • 11.
    Aboulfadl, Hisham
    et al.
    Chalmers Univ Technol, Dept Phys, Div Microstruct Phys, S-41296 Gothenburg, Sweden..
    Sopiha, Kostiantyn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för materialvetenskap, Solcellsteknik.
    Keller, Jan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för materialvetenskap, Solcellsteknik.
    Larsen, Jes K
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för materialvetenskap, Solcellsteknik.
    Scragg, Jonathan J.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för materialvetenskap, Solcellsteknik.
    Persson, Clas
    Univ Oslo, Ctr Mat Sci & Nanotechnol, Dept Phys, N-0316 Oslo, Norway.;KTH Royal Inst Technol, Dept Mat Sci & Engn, Div Appl Mat Phys, S-10044 Stockholm, Sweden..
    Thuvander, Mattias
    Chalmers Univ Technol, Dept Phys, Div Microstruct Phys, S-41296 Gothenburg, Sweden..
    Edoff, Marika
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för materialvetenskap, Solcellsteknik.
    Alkali Dispersion in (Ag,Cu)(In,Ga)Se-2 Thin Film Solar Cells-Insight from Theory and Experiment2021Ingår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 13, nr 6, s. 7188-7199Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Silver alloying of Cu(In,Ga)Se-2 absorbers for thin film photovoltaics offers improvements in open-circuit voltage, especially when combined with optimal alkali-treatments and certain Ga concentrations. The relationship between alkali distribution in the absorber and Ag alloying is investigated here, combining experimental and theoretical studies. Atom probe tomography analysis is implemented to quantify the local composition in grain interiors and at grain boundaries. The Na concentration in the bulk increases up to similar to 60 ppm for [Ag]/([Ag] + [Cu]) = 0.2 compared to similar to 20 ppm for films without Ag and up to similar to 200 ppm for [Ag]/([Ag] + [Cu]) = 1.0. First-principles calculations were employed to evaluate the formation energies of alkali-on-group-I defects (where group-I refers to Ag and Cu) in (Ag,Cu)(In,Ga)Se-2 as a function of the Ag and Ga contents. The computational results demonstrate strong agreement with the nanoscale analysis results, revealing a clear trend of increased alkali bulk solubility with the Ag concentration. The present study, therefore, provides a more nuanced understanding of the role of Ag in the enhanced performance of the respective photovoltaic devices.

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    FULLTEXT01
  • 12.
    Abrashev, Miroslav V.
    et al.
    Univ Sofia St Kliment Ohridski, Fac Phys, Sofia 1164, Bulgaria.
    Chernev, Petko
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik. Free Univ Berlin, Fachbereich Phys, Arnimallee 14, D-14195 Berlin, Germany.
    Kubella, Paul
    Free Univ Berlin, Fachbereich Phys, Arnimallee 14, D-14195 Berlin, Germany.
    Mohammadi, Mohammad Reza
    Free Univ Berlin, Fachbereich Phys, Arnimallee 14, D-14195 Berlin, Germany;Univ Sistan & Baluchestan, Dept Phys, Zahedan 9816745845, Iran.
    Pasquini, Chiara
    Free Univ Berlin, Fachbereich Phys, Arnimallee 14, D-14195 Berlin, Germany.
    Dau, Holger
    Free Univ Berlin, Fachbereich Phys, Arnimallee 14, D-14195 Berlin, Germany.
    Zaharieva, Ivelina
    Free Univ Berlin, Fachbereich Phys, Arnimallee 14, D-14195 Berlin, Germany.
    Origin of the heat-induced improvement of catalytic activity and stability of MnOx electrocatalysts for water oxidation2019Ingår i: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 7, nr 28, s. 17022-17036Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Catalysis of the oxygen evolution reaction (OER) by earth-abundant materials in the near-neutral pH regime is of great interest as it is the key reaction for non-fossil fuel production. To address the pertinent stability problems and insufficiently understood structure-activity relations, we investigate the influence of moderate annealing (100-300 degrees C for 20 min) for two types of electrodeposited Mn oxide films with contrasting properties. Upon annealing, the originally inactive and structurally well-ordered Oxide 1 of birnessite type became as OER active as the non-heated Oxide 2, which has a highly disordered atomic structure. Oxide 2 also improved its activity upon heating, but more important is the stability improvement: the operation time increased by about two orders of magnitude (in 0.1 M KPi at pH 7). Aiming at atomistic understanding, electrochemical methods including quantitative analysis of impedance spectra, X-ray spectroscopy (XANES and EXAFS), and adapted optical spectroscopies (infrared, UV-vis and Raman) identified structure-reactivity relations. Oxide structures featuring both di-mu-oxo bridged Mn ions and (close to) linear mono-mu-oxo Mn3+-O-Mn4+ connectivity seem to be a prerequisite for OER activity. The latter motif likely stabilizes Mn3+ ions at higher potentials and promotes electron/hole hopping, a feature related to electrical conductivity and reflected in the strongly accelerated rates of Mn oxidation and O-2 formation. Poor charge mobility, which may result from a low level of Mn3+ ions at high potentials, likely promotes inactivation after prolonged operation. Oxide structures related to the perovskite-like zeta-Mn2O3 were formed after the heating of Oxide 2 and could favour stabilization of Mn ions in oxidation states lower than +4. This rare phase was previously found only at high pressure (20 GPa) and temperature (1200 degrees C) and this is the first report where it was stable under ambient conditions.

  • 13.
    Achenbach, Jan-Ole
    et al.
    Rhein Westfal TH Aachen, Mat Chem, Kopernikusstr 10, D-52074 Aachen, Germany.
    Karimi Aghda, Soheil
    Rhein Westfal TH Aachen, Mat Chem, Kopernikusstr 10, D-52074 Aachen, Germany.
    Hans, Marcus
    Rhein Westfal TH Aachen, Mat Chem, Kopernikusstr 10, D-52074 Aachen, Germany.
    Primetzhofer, Daniel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Holzapfel, Damian M.
    Rhein Westfal TH Aachen, Mat Chem, Kopernikusstr 10, D-52074 Aachen, Germany.
    Miljanovic, Danilo J.
    Rhein Westfal TH Aachen, Mat Chem, Kopernikusstr 10, D-52074 Aachen, Germany.
    Schneider, Jochen M.
    Rhein Westfal TH Aachen, Mat Chem, Kopernikusstr 10, D-52074 Aachen, Germany.
    Low temperature oxidation behavior of Mo2BC coatings2020Ingår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 38, nr 2, artikel-id 023403Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Mo2BC exhibits a unique combination of high stiffness and moderate ductility, enabling the application as a protective and wear resistant coating. As the low temperature oxidation behavior of Mo2BC coatings is unexplored, direct current magnetron sputtered Mo2BC coatings were oxidized at temperatures ranging from 500 to 100 degrees C for up to 28 days. Time-of-flight elastic recoil detection analysis reveals that the onset of oxidation takes place at approximately 300 degrees C as a significant increase in the O content was observed. Crystalline oxide scales containing orthorhombic MoO3 were identified after oxidation for 15 min at 500 degrees C and 10 days at 200 degrees C. Isothermal oxidation at 200 and 100 degrees C exhibits oxide scale thicknesses of 401 +/- 33 and 22 +/- 10 nm after 14 days. Oxidation for 28 days at 100 degrees C exhibits an oxide scale thickness of 13 +/- 3 nm, which is comparable to the aforementioned oxide scale thickness after oxidation for 14 days at 100 degrees C. Based on the combination of mechanical properties and the here reported low temperature oxidation behavior, Mo2BC coatings qualify for applications in solid wood machining and low temperature forming processes at temperatures close to 100 degrees C or below.

  • 14.
    Achenbach, Jan-Ole
    et al.
    Rhein Westfal TH Aachen, Mat Chem, Kopernikusstr 10, D-52074 Aachen, Germany.
    Sahu, Rajib
    Max Planck Inst Eisenforsch GmbH, Max Planck Str 1, D-40237 Dusseldorf, Germany.
    Voelker, Bernhard
    Rhein Westfal TH Aachen, Mat Chem, Kopernikusstr 10, D-52074 Aachen, Germany;Max Planck Inst Eisenforsch GmbH, Max Planck Str 1, D-40237 Dusseldorf, Germany.
    Hans, Marcus
    Rhein Westfal TH Aachen, Mat Chem, Kopernikusstr 10, D-52074 Aachen, Germany.
    Primetzhofer, Daniel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi.
    Miljanovic, Danilo J.
    Rhein Westfal TH Aachen, Mat Chem, Kopernikusstr 10, D-52074 Aachen, Germany.
    Scheu, Christina
    Rhein Westfal TH Aachen, Mat Chem, Kopernikusstr 10, D-52074 Aachen, Germany;Max Planck Inst Eisenforsch GmbH, Max Planck Str 1, D-40237 Dusseldorf, Germany.
    Schneider, Jochen M.
    Rhein Westfal TH Aachen, Mat Chem, Kopernikusstr 10, D-52074 Aachen, Germany;Max Planck Inst Eisenforsch GmbH, Max Planck Str 1, D-40237 Dusseldorf, Germany.
    Synthesis and Properties of Orthorhombic MoAlB Coatings2019Ingår i: Coatings, ISSN 2079-6412, Vol. 9, nr 8, artikel-id 510Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    MoAlB is a potential candidate for high-temperature application since a dense, adherent alumina scale is formed. While, based on X-ray diffraction investigations, the formation of phase pure orthorhombic MoAlB coatings is observed, energy dispersive X-ray spectroscopy carried out in a scanning transmission electron microscope reveals the presence of Al-rich and O-rich regions within the MoAlB matrix. The oxidation kinetics of coatings and bulk is similar to the scale thickness formed on the MoAlB coating after oxidation at 1200 degrees C for 30 min is similar to the one extrapolated for bulk MoAlB. Furthermore, the oxidation kinetics of MoAlB coatings is significantly lower than the one reported for bulk Ti2AlC. Finally, the elastic properties measured for the as-deposited coatings are consistent ab initio predictions.

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    FULLTEXT01
  • 15. Acker, Pascal
    et al.
    Rzesny, Luisa
    Marchiori, Cleber F. N.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Araujo, Carlos Moyses
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Esser, Birgit
    π-Conjugation Enables Ultra-High Rate Capabilities and Cycling Stabilities in Phenothiazine Copolymers as Cathode-Active Battery Materials2019Ingår i: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 29, nr 45, artikel-id 1906436Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In recent years, organic battery cathode materials have emerged as an attractive alternative to metal oxide–based cathodes. Organic redox polymers that can be reversibly oxidized are particularly promising. A drawback, however, often is their limited cycling stability and rate performance in a high voltage range of more than 3.4 V versus Li/Li+. Herein, a conjugated copolymer design with phenothiazine as a redox‐active group and a bithiophene co‐monomer is presented, enabling ultra‐high rate capability and cycling stability. After 30 000 cycles at a 100C rate, >97% of the initial capacity is retained. The composite electrodes feature defined discharge potentials at 3.6 V versus Li/Li+ due to the presence of separated phenothiazine redox centers. The semiconducting nature of the polymer allows for fast charge transport in the composite electrode at a high mass loading of 60 wt%. A comparison with three structurally related polymers demonstrates that changing the size, amount, or nature of the side groups leads to a reduced cell performance. This conjugated copolymer design can be used in the development of advanced redox polymers for batteries.

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    fulltext
  • 16.
    Adalsteinsson, Alfred
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström.
    Reactions of Li-metal electrodes in contact with electrolytes, characterized by surface analysis techniques2020Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
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    Li_metal_XPS_ALFRED_2020
  • 17.
    Adalsteinsson, Sigurbjörn Már
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi.
    Moro, Marcos V.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Moldarev, Dmitrii
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialfysik. Moscow Engn Phys Inst, Dept Mat Sci, Moscow 115409S, Russia..
    Droulias, Sotiris
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandemlaboratoriet.
    Wolff, Max
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialfysik. Moscow Engn Phys Inst, Dept Mat Sci, Moscow 115409S, Russia..
    Primetzhofer, Daniel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik. Sweden.;Uppsala Univ, Tandem Lab, Box 529, S-75120 Uppsala, Sweden..
    Correlating chemical composition and optical properties of photochromic rare-earth oxyhydrides using ion beam analysis2020Ingår i: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 485, s. 36-40Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We relate the photochromic response of rare-earth oxyhydride thin films (YHO, NdHO, GdHO and DyHO) synthesized by reactive magnetron sputtering to chemical composition. Depth profiles of the sample composition are extracted by a multi-method ion beam analysis approach. The total areal density of the thin films is deduced from Rutherford Backscattering Spectrometry while coincidence Time-of-Flight/Energy Elastic Recoil Detection Analysis provides depth-profiles of the film constituents. High-resolution depth profiles of the concentration of light species, i.e. hydrogen and oxygen, are additionally extracted from Nuclear Reaction Analysis and Elastic Backscattering Spectrometry, respectively. The photochromic response of the films is measured by optical transmission spectroscopy before and after illumination. We report photochromic properties for YHO, NdHO, GdHO and DyHO for chemical compositions described by the formula REH2-delta O delta in the range of 0.45 < 6 < 1.5.

  • 18.
    Adler, Anna
    et al.
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för immunologi, genetik och patologi, Vaskulärbiologi.
    Fritsch, Marlene
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för immunologi, genetik och patologi.
    Fromell, Karin
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för immunologi, genetik och patologi, Vaskulärbiologi.
    Leneweit, Gero
    Carl Gustav Carus-Institute, Association for the Promotion of Cancer Therapy, Niefern-Öschelbronn, Germany.
    Ekdahl, Kristina N.
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för immunologi, genetik och patologi, Vaskulärbiologi. Linnaeus Center of Biomaterials Chemistry, Linnaeus University, SE-391 82 Kalmar, Sweden.
    Nilsson, Bo
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för immunologi, genetik och patologi, Vaskulärbiologi.
    Teramura, Yuji
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för immunologi, genetik och patologi, Vaskulärbiologi. Cellular and Molecular Biotechnology Research Institute (CMB), National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central Fifth, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan; Master's/Doctoral Program in Life Science Innovation (T-LSI), University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577, Japan.
    Regulation of the innate immune system by fragmented heparin-conjugated lipids on lipid bilayered membranes in vitro2023Ingår i: Journal of materials chemistry. B, ISSN 2050-750X, E-ISSN 2050-7518, Vol. 11, nr 46, s. 11121-11134Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Surface modification with heparin is a powerful biomaterial coating strategy that protects against innate immunity activation since heparin is a part of the proteoglycan heparan sulfate on cell surfaces in the body. We studied the heparinization of cellular and material surfaces via lipid conjugation to a heparin-binding peptide. In the present study, we synthesized fragmented heparin (fHep)-conjugated phospholipids and studied their regulation of the innate immune system on a lipid bilayered surface using liposomes. Liposomes have versatile applications, such as drug-delivery systems, due to their ability to carry a wide range of molecules. Owing to their morphological similarity to cell membranes, they can also be used to mimic a simple cell-membrane to study protein–lipid interactions. We investigated the interaction of complement-regulators, factor H and C4b-binding protein (C4BP), as well as the coagulation inhibitor antithrombin (AT), with fHep-lipids on the liposomal surface. Herein, we studied the ability of fHep-lipids to recruit factor H, C4BP, and AT using a quartz crystal microbalance with dissipation monitoring. With dynamic light scattering, we demonstrated that liposomes could be modified with fHep-lipids and were stable up to 60 days at 4 °C. Using a capillary western blot-based method (Wes), we showed that fHep-liposomes could recruit factor H in a model system using purified proteins and assist in the degradation of the active complement protein C3b to iC3b. Furthermore, we found that fHep-liposomes could recruit factor H and AT from human plasma. Therefore, the use of fHep-lipids could be a potential coating for liposomes and cell surfaces to regulate the immune system on the lipid surface.

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  • 19.
    Adolfsson, Karin H. H.
    et al.
    KTH Royal Inst Technol, Dept Fibre & Polymer Technol, S-10044 Stockholm, Sweden..
    Huang, Ping
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik.
    Golda-Cepa, Monika
    Jagiellonian Univ, Fac Chem, PL-30387 Krakow, Poland..
    Xu, Huan
    China Univ Min & Technol, Sch Mat Sci & Phys, Xuzhou 221116, Peoples R China..
    Kotarba, Andrzej
    Jagiellonian Univ, Fac Chem, PL-30387 Krakow, Poland..
    Hakkarainen, Minna
    KTH Royal Inst Technol, Dept Fibre & Polymer Technol, S-10044 Stockholm, Sweden..
    Scavenging of DPPH by Persistent Free Radicals in Carbonized Particles2023Ingår i: Advanced Sustainable Systems, ISSN 2366-7486, Vol. 7, nr 3, artikel-id 2200425Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Persistent free radicals (PFR) in carbonized particles may play a role in degradation of environmental compounds. The influence of PFR is evaluated in various carbonized particles on their radical scavenging efficiency upon the common radical indicator 2-2-diphenyl-1-picrylhydrazyl (DPPH). Carbonized particles are derived by hydrothermal carbonization of glucose (C-W) or glucose and urea (NC-W) and ionothermal carbonization of glucose and urea ionic liquid (IL) (NC-IL). The carbonized materials contain OH/COOH, C=C, and C-O functionalities. The addition of urea introduces NH/NH2 functionalities. The content of polar surface groups is lower in IL-processed NC-IL. The scavenging ability, measured as DPPH UV–vis absorption decline, increases with concentration and time for all particles, while the efficiency changes are in the order of C-W > NC-W > NC-IL. Electron paramagnetic resonance analysis reveals similar radical concentration in all carbonized materials studied. The difference in efficiency is, thus, not directly related to the PFR concentration but rather to the type of PFR, surface functionalities and/or scavenging mechanism. According to the g-values, radicals in these particles are carbon-centered. The minor variation in g-values suggests interactions between the radicals and their environmental functional groups. This provides insights into the influence of PFR in carbonized materials on their radical scavenging efficiency.

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    fulltext
  • 20.
    Afroze, Shammya
    et al.
    Univ Brunei Darussalam, Fac Integrated Technol, Jalan Tungku Link, BE-1410 Gadong, Brunei; Chalmers Univ Technol, Dept Chem & Chem Engn, SE-41296 Gothenburg, Sweden..
    Torino, Nico
    Chalmers Univ Technol, Dept Chem & Chem Engn, SE-41296 Gothenburg, Sweden..
    Reza, Md Sumon
    Univ Brunei Darussalam, Fac Integrated Technol, Jalan Tungku Link, BE-1410 Gadong, Brunei..
    Radenahmad, Nikdalila
    Univ Brunei Darussalam, Fac Integrated Technol, Jalan Tungku Link, BE-1410 Gadong, Brunei..
    Cheok, Quentin
    Univ Brunei Darussalam, Fac Integrated Technol, Jalan Tungku Link, BE-1410 Gadong, Brunei..
    Henry, Paul F.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi. Rutherford Appleton Lab, ISIS Pulsed Neutron & Muon Facil, Harwell Campus, Didcot OX11 0QX, Oxon, England..
    Azad, Abul K.
    Univ Brunei Darussalam, Fac Integrated Technol, Jalan Tungku Link, BE-1410 Gadong, Brunei..
    Structure-conductivity relationship of PrBaMnMoO6-δ through in-situ measurements: A neutron diffraction study2021Ingår i: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 47, nr 1, s. 541-546Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The structural and electrochemical properties of the double perovskite-type oxide, PrBaMnMoO6-δ, was investigated using neutron diffraction with in-situ conductivity measurement under a dry Argon atmosphere from 25 °C to 700 °C. A Rietveld refinement of the neutron diffraction data confirmed monoclinic symmetry in the P21/n space group. Rietveld refinement also confirms the unit cell parameters of a = 5.6567 (1) Å, b = 5.6065 (2) Å, c = 7.9344 (1) Å and β = 84.43° with reliable atomic positions and refinement factors (R-factors). Neutron diffraction data refinement shows two minor phases (< 5%), an orthorhombic AB2O5 type phase of PrMn2O5 in the Pbam (No. 32) space group with unit cell parameters, a = 7.9672 (1) Å, b = 8.9043 (2) Å and c = 5.8540 (1) Å and a scheelite phase of BaMoO4 in the tetragonal I41/a (88) space group with the unit cell parameters, a = b = 5.9522 (1) Å, and c = 12.3211 (2) Å. Morphological images revealed a porous and intertwined microstructure. In-situ conductivity measurement shows that the total conductivity of this material was 130.84 Scm−1 at 700 °C.

  • 21.
    Afroze, Shammya
    et al.
    Univ Brunei Darussalam, Fac Integrated Technol, Jalan Tungku Link, BE-1410 Bandar Seri Begawan, Brunei; Chalmers Univ Technol, Dept Chem & Chem Engn, SE-41296 Gothenburg, Sweden.
    Yilmaz, Duygu
    Chalmers Univ Technol, Dept Chem & Chem Engn, SE-41296 Gothenburg, Sweden.
    Reza, Md Sumon
    Univ Brunei Darussalam, Fac Integrated Technol, Jalan Tungku Link, BE-1410 Bandar Seri Begawan, Brunei.
    Henry, Paul F.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi. Rutherford Appleton Lab, ISIS Pulsed Neutron & Muon Facil, Harwell Campus, Didcot OX11 0QX, Oxon, England.
    Cheok, Quentin
    Univ Brunei Darussalam, Fac Integrated Technol, Jalan Tungku Link, BE-1410 Bandar Seri Begawan, Brunei.
    Zaini, Juliana H.
    Univ Brunei Darussalam, Fac Integrated Technol, Jalan Tungku Link, BE-1410 Bandar Seri Begawan, Brunei.
    Azad, Abul K.
    Univ Brunei Darussalam, Fac Integrated Technol, Jalan Tungku Link, BE-1410 Bandar Seri Begawan, Brunei.
    Issakhov, Alibek
    Al Farabi Kazakh Natl Univ, Dept Math & Comp Modelling, Fac Mech & Math, Alma Ata, Kazakhstan.
    Sadeghzadeh, Milad
    Univ Tehran, Dept Renewable Energy & Environm Engn, Tehran, Iran.
    Investigation of Structural and Thermal Evolution in Novel Layered Perovskite NdSrMn2O5+δ via Neutron Powder Diffraction and Thermogravimetric Analysis2020Ingår i: International Journal of Chemical Engineering, ISSN 1687-806X, E-ISSN 1687-8078, Vol. 2020, artikel-id 6642187Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Neutron diffraction is one of the best methods for structural analysis of a complex, layered perovskite material with low symmetry by accurately detecting the oxygen positions through octahedral tilting. In this research, the crystal structure of NdSrMn2O5+δ was identified through X-ray diffraction (XRD) and neutron powder diffraction (NPD) at room temperature (RT), which indicated the formation of a layered structure in orthorhombic symmetry in the Pmmm (no. 47) space group. Rietveld refinement of the neutron diffraction data has confirmed the orthorhombic symmetry with unit cell parameters (a = 3.8367 (1) Å, b = 3.8643 (2) Å, and c = 7.7126 (1) Å), atomic positions, and oxygen occupancy. Thermogravimetric analysis revealed the total weight loss of about 0.10% for 20–950°C temperature, which occurred mainly to create oxygen vacancies at high temperatures. Rietveld analyses concurred with the XRD and neutron data allowing correlation of occupancy factors of the oxygen sites.

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    FULLTEXT01
  • 22.
    Aghda, Soheil Karimi
    et al.
    Rhein Westfal TH Aachen, Mat Chem, Kopernikusstr 10, D-52074 Aachen, Germany..
    Holzapfel, Damian M.
    Rhein Westfal TH Aachen, Mat Chem, Kopernikusstr 10, D-52074 Aachen, Germany..
    Music, Denis
    Malmö Univ, Dept Mat Sci & Appl Math, S-20506 Malmö, Sweden..
    Unutulmazsoy, Yeliz
    Leibniz Inst Surface Engn IOM, Permoserstr 15, D-04318 Leipzig, Germany..
    Mraz, Stanislav
    Rhein Westfal TH Aachen, Mat Chem, Kopernikusstr 10, D-52074 Aachen, Germany..
    Bogdanovski, Dimitri
    Rhein Westfal TH Aachen, Mat Chem, Kopernikusstr 10, D-52074 Aachen, Germany..
    Fidanboy, Gonenc
    Rhein Westfal TH Aachen, Mat Chem, Kopernikusstr 10, D-52074 Aachen, Germany..
    Hans, Marcus
    Rhein Westfal TH Aachen, Mat Chem, Kopernikusstr 10, D-52074 Aachen, Germany..
    Primetzhofer, Daniel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandemlaboratoriet.
    Mendez, Alba San Jose
    Deutsch Elektronen Synchrotron DESY, Notkestr 85, D-22607 Hamburg, Germany..
    Anders, Andre
    Leibniz Inst Surface Engn IOM, Permoserstr 15, D-04318 Leipzig, Germany.;Univ Leipzig, Felix Bloch Inst, Linnestr 5, D-04103 Leipzig, Germany..
    Schneider, Jochen M.
    Rhein Westfal TH Aachen, Mat Chem, Kopernikusstr 10, D-52074 Aachen, Germany..
    Ion kinetic energy- and ion flux-dependent mechanical properties and thermal stability of (Ti,Al)N thin films2023Ingår i: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 250, artikel-id 118864Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ion-irradiation-induced changes in structure, elastic properties, and thermal stability of metastable c-(Ti,Al)N thin films synthesized by high-power pulsed magnetron sputtering (HPPMS) and cathodic arc deposition (CAD) are systematically investigated by experiments and density functional theory (DFT) simulations. While films deposited by HPPMS show a random orientation at ion kinetic energies (Ek)>105 eV, an evolution towards (111) orientation is observed in CAD films for Ek>144 eV. The measured ion energy flux at the growing film surface is 3.3 times larger for CAD compared to HPPMS. Hence, it is inferred that formation of the strong (111) texture in CAD films is caused by the ion flux-and ion energy-induced strain energy minimization in defective c-(Ti,Al)N. The ion energy-dependent elastic modulus can be rationalized by considering the ion energy-and orientation -dependent formation of point defects from DFT predictions: The balancing effects of bombardment-induced Frenkel defects formation and the concurrent evolution of compressive intrinsic stress result in the apparent independence of the elastic modulus from Ek for HPPMS films without preferential orientation. However, an ion energy-dependent elastic modulus reduction of similar to 18% for the CAD films can be understood by considering the 34% higher Frenkel pair concentration formed at Ek=182 eV upon irradiation of the experimentally observed (111)-oriented (Ti,Al)N in comparison to the (200)-configuration at similar Ek. Moreover, the effect of Frenkel pair concentration on the thermal stability of metastable c-(Ti,Al)N is investigated by differential scanning calorimetry: Ion-irradiation-induced increase in Frenkel pairs concentration retards the wurtzite formation temperature by up to 206 degrees C.

  • 23.
    Agosta, Lorenzo
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Arismendi-Arrieta, Daniel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Dzugutov, Mikhail
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Hermansson, Kersti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Origin of the Hydrophobic Behaviour of Hydrophilic CeO22023Ingår i: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 62, nr 35, artikel-id e202303910Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The nature of the hydrophobicity found in rare-earth oxides is intriguing. The CeO2 (100) surface, despite its strongly hydrophilic nature, exhibits hydrophobic behaviour when immersed in water. In order to understand this puzzling and counter-intuitive effect we performed a detailed analysis of the water structure and dynamics. We report here an ab-initio molecular dynamics simulation (AIMD) study which demonstrates that the first water layer, in immediate contact with the hydroxylated CeO2 surface, is responsible for the effect behaving as a hydrophobic interface with respect to the rest of the liquid water. The hydrophobicity is manifested in several ways: a considerable diffusion enhancement of the confined liquid water as compared with bulk water at the same thermodynamic condition, a weak adhesion energy and few H-bonds above the hydrophobic water layer, which may also sustain a water droplet. These findings introduce a new concept in water/rare-earth oxide interfaces: hydrophobicity mediated by specific water patterns on a hydrophilic surface.

    Ladda ner fulltext (pdf)
    fulltext
  • 24.
    Agthe, Michael
    et al.
    Stockholm Univ, Arrhenius Lab, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden..
    Wetterskog, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets fysik.
    Bergström, Lennart
    Stockholm Univ, Arrhenius Lab, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden..
    Following the Assembly of Iron Oxide Nanocubes by Video Microscopy and Quartz Crystal Microbalance with Dissipation Monitoring2017Ingår i: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 33, nr 1, s. 303-310Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We have studied the growth of ordered arrays by evaporation-induced self-assembly of iron oxide nanocubes with edge lengths of 6.8 and 10.1 nm using video microscopy (VM) and quartz crystal microbalance with dissipation monitoring (QCM-D). Ex situ electron diffraction of the ordered arrays demonstrates that the crystal axes of the nanocubes are coaligned and confirms that the ordered arrays are mesocrystals. Time-resolved video microscopy shows that growth of the highly ordered arrays at slow solvent evaporation is controlled by particle diffusion and can be described by a simple growth model. The growth of each mesocrystal depends only on the number of nanoparticles within the accessible region irrespective of the relative time of formation. The mass of the dried mesocrystals estimated from the analysis of the bandwidth-shift-to-frequency-shift ratio correlates well with the total mass of the oleate-coated nanoparticles in the deposited dispersion drop.

  • 25.
    Ahlberg, Patrik
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Johansson, Fredrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Energimaterialens fysik.
    Zhang, Zhibin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Jansson, Ulf
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Zhang, Shi-Li
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Lindblad, Andreas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Energimaterialens fysik.
    Nyberg, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Defect formation in graphene during low-energy ion bombardment2016Ingår i: APL Materials, E-ISSN 2166-532X, Vol. 4, nr 4, artikel-id 046104Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This letter reports on a systematic investigation of sputter induced damage in graphene caused by low energy Ar+ ion bombardment. The integral numbers of ions per area (dose) as well as their energies are varied in the range of a few eV's up to 200 eV. The defects in the graphene are correlated to the dose/energy and different mechanisms for the defect formation are presented. The energetic bombardment associated with the conventional sputter deposition process is typically in the investigated energy range. However, during sputter deposition on graphene, the energetic particle bombardment potentially disrupts the crystallinity and consequently deteriorates its properties. One purpose with the present study is therefore to demonstrate the limits and possibilities with sputter deposition of thin films on graphene and to identify energy levels necessary to obtain defect free graphene during the sputter deposition process. Another purpose is to disclose the fundamental mechanisms responsible for defect formation in graphene for the studied energy range.

    Ladda ner fulltext (pdf)
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  • 26.
    Ahmad, Mariam
    et al.
    Univ Southern Denmark, Mads Clausen Inst, SDU Ctr Adv Photovolta & Thin Film Energy Devices, DK-6400 Sonderborg, Denmark.;Univ Southern Denmark, SDU Climate Cluster, DK-5230 Odense, Denmark..
    Cruguel, Herve
    Sorbonne Univ, Inst Nanosci Paris, CNRS, UMR 7588, F-75005 Paris, France..
    Ahmadpour, Mehrad
    Univ Southern Denmark, Mads Clausen Inst, SDU Ctr Adv Photovolta & Thin Film Energy Devices, DK-6400 Sonderborg, Denmark..
    Vannucchi, Noemi
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi. Sorbonne Univ, Inst Nanosci Paris, CNRS, UMR 7588, F-75005 Paris, France..
    Samie, Nahed Mohammad
    Sorbonne Univ, Inst Nanosci Paris, CNRS, UMR 7588, F-75005 Paris, France..
    Leuillet, Celine
    Sorbonne Univ, Inst Nanosci Paris, CNRS, UMR 7588, F-75005 Paris, France..
    Generalov, Alexander
    Lund Univ, MAX Lab 4, S-22100 Lund, Sweden..
    Li, Zheshen
    Aarhus Univ, Ctr Storage Ring Facil, Dept Phys & Astron, ISA, DK-8000 Aarhus C, Denmark..
    Madsen, Morten
    Univ Southern Denmark, Mads Clausen Inst, SDU Ctr Adv Photovolta & Thin Film Energy Devices, DK-6400 Sonderborg, Denmark.;Univ Southern Denmark, SDU Climate Cluster, DK-5230 Odense, Denmark..
    Witkowski, Nadine
    Sorbonne Univ, Inst Nanosci Paris, CNRS, UMR 7588, F-75005 Paris, France..
    Uncovering the Electronic State Interplay at Metal Oxide Electron Transport Layer/Nonfullerene Acceptor Interfaces in Stable Organic Photovoltaic Devices2023Ingår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 15, nr 47, s. 55065-55072Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The implementation of sputter-deposited TiOx as an electron transport layer in nonfullerene acceptor-based organic photovoltaics has been shown to significantly increase the long-term stability of devices compared to conventional solution-processed ZnO due to a decreased photocatalytic activity of the sputtered TiOx. In this work, we utilize synchrotron-based photoemission and absorption spectroscopies to investigate the interface between the electron transport layer, TiOx prepared by magnetron sputtering, and the nonfullerene acceptor, ITIC, prepared in situ by spray deposition to study the electronic state interplay and defect states at this interface. This is used to unveil the mechanisms behind the decreased photocatalytic activity of the sputter-deposited TiOx and thus also the increased stability of the organic solar cell devices. The results have been compared to similar measurements on anatase TiOx since anatase TiOx is known to have a strong photocatalytic activity. We show that the deposition of ITIC on top of the sputter-deposited TiOx results in an oxidation of Ti3+ species in the TiOx and leads to the emergence of a new O 1s peak that can be attributed to the oxygen in ITIC. In addition, increasing the thickness of ITIC on TiOx leads to a shift in the O 1s and C 1s core levels toward higher binding energies, which is consistent with electron transfer at the interface. Resonant photoemission at the Ti L-edge shows that oxygen vacancies in sputtered TiOx lie mostly in the surface region, which contrasts the anatase TiOx where an equal distribution between surface and subsurface oxygen vacancies is observed. Furthermore, it is shown that the subsurface oxygen vacancies in sputtered TiOx are strongly reduced after ITIC deposition, which can reduce the photocatalytic activity of the oxide, while the oxygen vacancies in model anatase TiOx are not affected upon ITIC deposition. This difference can explain the inferior photocatalytic activity of the sputter-deposited TiOx and thus also the increased stability of devices with sputter-deposited TiOx used as an electron transport layer.

  • 27.
    Ahmadi, Majid
    et al.
    University of Puerto Rico.
    Younesi, Reza
    Technical University of Denmark.
    Vegge, Tejs
    Technical University of Denmark.
    Guinel, Maxime J-F
    University of Puerto Rico.
    Nickel oxide crystalline nano flakes: synthesis, characterization and their use as anode in lithium-ion batteries2014Ingår i: Materials Research Express, E-ISSN 2053-1591, Vol. 1, nr 2, s. 025501-Artikel i tidskrift (Refereegranskat)
  • 28.
    Aijaz, Asim
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Ferreira, Fabio
    Univ Coimbra, SEG CEMMPRE Dept Mech Engn, Rua Luis Reis Santos, P-3030788 Coimbra, Portugal.
    Oliveira, Joao
    Univ Coimbra, SEG CEMMPRE Dept Mech Engn, Rua Luis Reis Santos, P-3030788 Coimbra, Portugal.
    Kubart, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Mechanical Properties of Hydrogen Free Diamond-Like Carbon Thin Films Deposited by High Power Impulse Magnetron Sputtering with Ne2018Ingår i: Coatings, ISSN 2079-6412, Vol. 8, nr 11, artikel-id 385Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Hydrogen-free diamond-like carbon (DLC) thin films are attractive for a wide range of industrial applications. One of the challenges related to the use of hard DLC lies in the high intrinsic compressive stresses that limit the film adhesion. Here, we report on the mechanical and tribological properties of DLC films deposited by High Power Impulse Magnetron Sputtering (HiPIMS) with Ne as the process gas. In contrast to standard magnetron sputtering as well as standard Ar-based HiPIMS process, the Ne-HiPIMS lead to dense DLC films with increased mass density (up to 2.65 g/cm(3)) and a hardness of 23 GPa when deposited on steel with a Cr + CrN adhesion interlayer. Tribological testing by the pin-on-disk method revealed a friction coefficient of 0.22 against steel and a wear rate of 2 x 10(-17) m(3)/Nm. The wear rate is about an order of magnitude lower than that of the films deposited using Ar. The differences in the film properties are attributed to an enhanced C ionization in the Ne-HiPIMS discharge.

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    FULLTEXT01
  • 29.
    Aijaz, Asim
    et al.
    Linkoping Univ, Dept Phys Chem & Biol, IFM Mat Phys, SE-58183 Linkoping, Sweden.;Uppsala Univ, Dept Engn Sci, Angstrom Lab, POB 534, SE-75121 Uppsala, Sweden..
    Louring, Sascha
    Aarhus Univ, Interdisciplinary Nanosci Ctr iNANO, Ny Munkegade 120, DK-8000 Aarhus C, Denmark.;Danish Technol Inst, Tribol Ctr, Teknol Pk,Kongsvang Alle 29, DK-8000 Aarhus C, Denmark..
    Lundin, Daniel
    Univ Paris Saclay, Univ Paris Sud, LPGP, CNRS,UMR 8578, F-91405 Orsay, France..
    Kubart, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Jensen, Jens
    Linkoping Univ, Dept Phys Chem & Biol, IFM Mat Phys, SE-58183 Linkoping, Sweden..
    Sarakinos, Kostas
    Linkoping Univ, Dept Phys Chem & Biol, IFM Mat Phys, SE-58183 Linkoping, Sweden..
    Helmersson, Ulf
    Linkoping Univ, Dept Phys Chem & Biol, IFM Mat Phys, SE-58183 Linkoping, Sweden..
    Synthesis of hydrogenated diamondlike carbon thin films using neon-acetylene based high power impulse magnetron sputtering discharges2016Ingår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 34, nr 6, artikel-id 061504Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Hydrogenated diamondlike carbon (DLC:H) thin films exhibit many interesting properties that can be tailored by controlling the composition and energy of the vapor fluxes used for their synthesis. This control can be facilitated by high electron density and/or high electron temperature plasmas that allow one to effectively tune the gas and surface chemistry during film growth, as well as the degree of ionization of the film forming species. The authors have recently demonstrated by adding Ne in an Ar-C high power impulse magnetron sputtering (HiPIMS) discharge that electron temperatures can be effectively increased to substantially ionize C species [Aijaz et al., Diamond Relat. Mater. 23, 1 (2012)]. The authors also developed an Ar-C2H2 HiPIMS process in which the high electron densities provided by the HiPIMS operation mode enhance gas phase dissociation reactions enabling control of the plasma and growth chemistry [Aijaz et al., Diamond Relat. Mater. 44, 117 (2014)]. Seeking to further enhance electron temperature and thereby promote electron impact induced interactions, control plasma chemical reaction pathways, and tune the resulting film properties, in this work, the authors synthesize DLC: H thin films by admixing Ne in a HiPIMS based Ar/C2H2 discharge. The authors investigate the plasma properties and discharge characteristics by measuring electron energy distributions as well as by studying discharge current characteristics showing an electron temperature enhancement in C2H2 based discharges and the role of ionic contribution to the film growth. These discharge conditions allow for the growth of thick (>1 mu m) DLC: H thin films exhibiting low compressive stresses (similar to 0.5 GPa), high hardness (similar to 25 GPa), low H content (similar to 11%), and density in the order of 2.2 g/cm(3). The authors also show that film densification and change of mechanical properties are related to H removal by ion bombardment rather than subplantation.

  • 30.
    Aimonen, Kukka
    et al.
    Finnish Inst Occupat Hlth, Box 40, Helsinki 00032, Finland..
    Suhonen, Satu
    Finnish Inst Occupat Hlth, Box 40, Helsinki 00032, Finland..
    Hartikainen, Mira
    Finnish Inst Occupat Hlth, Box 40, Helsinki 00032, Finland..
    Lopes, Viviana
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för materialvetenskap, Nanoteknologi och funktionella material.
    Norppa, Hannu
    Finnish Inst Occupat Hlth, Box 40, Helsinki 00032, Finland..
    Ferraz, Natalia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för materialvetenskap, Nanoteknologi och funktionella material.
    Catalan, Julia
    Finnish Inst Occupat Hlth, Box 40, Helsinki 00032, Finland.;Univ Zaragoza, Dept Anat Embryol & Genet, Zaragoza 50013, Spain..
    Role of Surface Chemistry in the In Vitro Lung Response to Nanofibrillated Cellulose2021Ingår i: Nanomaterials, E-ISSN 2079-4991, Vol. 11, nr 2, artikel-id 389Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Wood-derived nanofibrillated cellulose (NFC) has emerged as a sustainable material with a wide range of applications and increasing presence in the market. Surface charges are introduced during the preparation of NFC to facilitate the defibrillation process, which may also alter the toxicological properties of NFC. In the present study, we examined the in vitro toxicity of NFCs with five surface chemistries: nonfunctionalized, carboxymethylated, phosphorylated, sulfoethylated, and hydroxypropyltrimethylammonium-substituted. The NFC samples were characterized for surface functional group density, surface charge, and fiber morphology. Fibril aggregates predominated in the nonfunctionalized NFC, while individual nanofibrils were observed in the functionalized NFCs. Differences in surface group density among the functionalized NFCs were reflected in the fiber thickness of these samples. In human bronchial epithelial (BEAS-2B) cells, all NFCs showed low cytotoxicity (CellTiter-GloVR luminescent cell viability assay) which never exceeded 10% at any exposure time. None of the NFCs induced genotoxic effects, as evaluated by the alkaline comet assay and the cytokinesis-block micronucleus assay. The nonfunctionalized and carboxymethylated NFCs were able to increase intracellular reactive oxygen species (ROS) formation (chloromethyl derivative of 2 ',7 '-dichlorodihydrofluorescein diacetate assay). However, ROS induction did not result in increased DNA or chromosome damage.

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    FULLTEXT01
  • 31.
    Akbari-Saatlu, Mehdi
    et al.
    Mid Sweden Univ, Dept Elect Design, SE-85170 Sundsvall, Sweden.
    Procek, Marcin
    Mid Sweden Univ, Dept Elect Design, SE-85170 Sundsvall, Sweden.;Silesian Tech Univ, Dept Optoelect, PL-44100 Gliwice, Poland.
    Mattsson, Claes
    Mid Sweden Univ, Dept Elect Design, SE-85170 Sundsvall, Sweden.
    Thungström, Göran
    Mid Sweden Univ, Dept Elect Design, SE-85170 Sundsvall, Sweden.
    Törndahl, Tobias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för materialvetenskap, Solcellsteknik.
    Li, Ben
    Guangdong Greater Bay Area Inst Integrated Circui, Guangzhou 510535, Peoples R China.
    Su, Jiale
    Guangdong Greater Bay Area Inst Integrated Circui, Guangzhou 510535, Peoples R China.;Chinese Acad Sci, Inst Microelect, Key Lab Microelect Devices & Integrated Technol, Beijing 100029, Peoples R China.
    Xiong, Wenjuan
    Chinese Acad Sci, Inst Microelect, Key Lab Microelect Devices & Integrated Technol, Beijing 100029, Peoples R China.
    Radamson, Henry H.
    Mid Sweden Univ, Dept Elect Design, SE-85170 Sundsvall, Sweden.;Guangdong Greater Bay Area Inst Integrated Circui, Guangzhou 510535, Peoples R China.;Chinese Acad Sci, Inst Microelect, Key Lab Microelect Devices & Integrated Technol, Beijing 100029, Peoples R China.
    Nanometer-Thick ZnO/SnO2 Heterostructures Grown on Alumina for H2S Sensing2022Ingår i: ACS Applied Nano Materials, E-ISSN 2574-0970, Vol. 5, nr 5, s. 6954-6963Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Designing heterostructure materials at the nanoscale is a well-known method to enhance gas sensing performance. In this study, a mixed solution of zinc chloride and tin (II) chloride dihydrate, dissolved in ethanol solvent, was used as the initial precursor for depositing the sensing layer on alumina substrates using the ultrasonic spray pyrolysis (USP) method. Several ZnO/SnO2 heterostructures were grown by applying different ratios in the initial precursors. These heterostructures were used as active materials for the sensing of H2S gas molecules. The results revealed that an increase in the zinc chloride in the USP precursor alters the H2S sensitivity of the sensor. The optimal working temperature was found to be 450 degrees C. The sensor, containing 5:1 (ZnCl2: SnCl2 center dot 2H(2)O) ratio in the USP precursor, demonstrates a higher response than the pure SnO2 (similar to 95 times) sample and other heterostructures. Later, the selectivity of the ZnO/SnO2 heterostructures toward 5 ppm NO2, 200 ppm methanol, and 100 ppm of CH4, acetone, and ethanol was also examined. The gas sensing mechanism of the ZnO/SnO2 was analyzed and the remarkably enhanced gas-sensing performance was mainly attributed to the heterostructure formation between ZnO and SnO2. The synthesized materials were also analyzed by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray, transmission electron microscopy, and X-ray photoelectron spectra to investigate the material distribution, grain size, and material quality of ZnO/SnO2 heterostructures.

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  • 32.
    Aktekin, Burak
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Brant, William
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Valvo, Mario
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Marzano, Fernanda
    Scania CV AB.
    Zipprich, Wolfgang
    Volkswagen AG.
    Brandell, Daniel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Cation Ordering and Oxygen Release in LiNi0.5-xMn1.5+xO4-y (LNMO)—In Situ Neutron Diffraction and Performance in Li-Ion Full Cells2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    LiNi0.5Mn1.5O4 (LNMO) is a promising spinel-type positive electrode for lithium ion batteries as it operates at high voltage and possesses high power capability. However, rapid performance degradation in full cells, especially at elevated temperatures, is a problem. There has been a considerable interest in its crystal structure as this is known to affect its electrochemical performance. LNMO can adopt a P4332 (cation ordered) or Fd-3m (cation disordered) arrangement depending on the synthesis conditions. Most of the studies in literature agree on better electrochemical performance for disordered LNMO [1], however, a clear understanding of the reason for this behaviour is still lacking. This partly arises from the fact that synthesis conditions leading to disordering also lead to oxygen deficiency, rock-salt impurities and therefore generate some Mn3+ [2]. Most commonly, X-ray diffraction is used to characterize these materials, however, accurate structural analysis is difficult due to the near identical scattering lengths of Mn and Ni. This is not the case for neutron diffraction. In this study, an in-situ neutron diffraction heating-cooling experiment was conducted on slightly Mn-rich LNMO under pure oxygen atmosphere in order to investigate relationship between disordering and oxygen deficiency. The study shows for the first time that there is no direct relationship between oxygen loss and cation disordering, as disordering starts prior to oxygen release. Our findings suggest that it is possible to obtain samples with varying degrees of ordering, yet with the same oxygen content and free from impurities. In the second part of the study, highly ordered, partially ordered and fully disordered samples have been tested in LNMO∥LTO (Li4Ti5O12) full cells at 55 °C. It is shown that differences in their performances arise only after repeated cycling, while all the samples behave similarly at the beginning of the test. The difference is believed to be related to instabilities of LNMO at higher voltages, that is, in its lower lithiation states.

    [1] A. Manthiram, K. Chemelewski, E.-S. Lee, Energy Environ. Sci. 7 (2014) 1339.

    [2] M. Kunduraci, G.G. Amatucci, J. Power Sources. 165 (2007) 359–367.

  • 33.
    Aktekin, Burak
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Hernández, Guiomar
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Younesi, Reza
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Brandell, Daniel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Concentrated LiFSI-€“Ethylene Carbonate Electrolytes and Their Compatibility with High-Capacity and High-Voltage Electrodes2022Ingår i: ACS Applied Energy Materials, E-ISSN 2574-0962, Vol. 5, nr 1, s. 585-595Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The unusual physical and chemical properties of electrolytes with excessive salt contents have resulted in rising interest in highly concentrated electrolytes, especially for their application in batteries. Here, we report strikingly good electrochemical performance in terms of conductivity and stability for a binary electrolyte system, consisting of lithium bis(fluorosulfonyl)imide (LiFSI) salt and ethylene carbonate (EC) solvent. The electrolyte is explored for different cell configurations spanning both high-capacity and high-voltage electrodes, which are well known for incompatibilities with conventional electrolyte systems: Li metal, Si/graphite composites, LiNi0.33Mn0.33Co0.33O2 (NMC111), and LiNi0.5Mn1.5O4 (LNMO). As compared to a LiTFSI counterpart as well as a common LP40 electrolyte, it is seen that the LiFSI:EC electrolyte system is superior in Li-metal–Si/graphite cells. Moreover, in the absence of Li metal, it is possible to use highly concentrated electrolytes (e.g., 1:2 salt:solvent molar ratio), and a considerable improvement on the electrochemical performance of NMC111-Si/graphite cells was achieved with the LiFSI:EC 1:2 electrolyte both at the room temperature and elevated temperature (55 °C). Surface characterization with scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) showed the presence of thicker surface film formation with the LiFSI-based electrolyte as compared to the reference electrolyte (LP40) for both positive and negative electrodes, indicating better passivation ability of such surface films during extended cycling. Despite displaying good stability with the NMC111 positive electrode, the LiFSI-based electrolyte showed less compatibility with the high-voltage spinel LNMO electrode (4.7 V vs Li+/Li).

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  • 34.
    Aktekin, Burak
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Lacey, Matthew J.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Nordh, Tim
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Younesi, Reza
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Tengstedt, Carl
    Scania CV AB, SE-15187 Sodertalje, Sweden.
    Zipprich, Wolfgang
    Volkswagen AG, D-38436 Wolfsburg, Germany.
    Brandell, Daniel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Understanding the Capacity Loss in LiNi0.5Mn1.5O4-Li4Ti5O12 Lithium-Ion Cells at Ambient and Elevated Temperatures2018Ingår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 122, nr 21, s. 11234-11248Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The high-voltage spinel LiNi0.5Mn1.5O4, (LNMO) is an attractive positive electrode because of its operating voltage around 4.7 V (vs Li/Li+) and high power capability. However, problems including electrolyte decomposition at high voltage and transition metal dissolution, especially at elevated temperatures, have limited its potential use in practical full cells. In this paper, a fundamental study for LNMO parallel to Li4Ti5O12 (LTO) full cells has been performed to understand the effect of different capacity fading mechanisms contributing to overall cell failure. Electrochemical characterization of cells in different configurations (regular full cells, back-to-back pseudo-full cells, and 3-electrode full cells) combined with an intermittent current interruption technique have been performed. Capacity fade in the full cell configuration was mainly due to progressively limited lithiation of electrodes caused by a more severe degree of parasitic reactions at the LTO electrode, while the contributions from active mass loss from LNMO or increases in internal cell resistance were minor. A comparison of cell formats constructed with and without the possibility of cross-talk indicates that the parasitic reactions on LTO occur because of the transfer of reaction products from the LNMO side. The efficiency of LTO is more sensitive to temperature, causing a dramatic increase in the fading rate at 55 degrees C. These observations show how important the electrode interactions (cross-talk) can be for the overall cell behavior. Additionally, internal resistance measurements showed that the positive electrode was mainly responsible for the increase of resistance over cycling, especially at 55 degrees C. Surface characterization showed that LNMO surface layers were relatively thin when compared with the solid electrolyte interphase (SEI) on LTO. The SEI on LTO does not contribute significantly to overall internal resistance even though these films are relatively thick. X-ray absorption near-edge spectroscopy measurements showed that the Mn and Ni observed on the anode were not in the metallic state; the presence of elemental metals in the SEI is therefore not implicated in the observed fading mechanism through a simple reduction process of migrated metal cations.

  • 35.
    Aktekin, Burak
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Lacey, Matthew
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Nordh, Tim
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Tengstedt, Carl
    Scania CV AB.
    Brandell, Daniel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Understanding the Rapid Capacity Fading of LNMO-LTO Lithium-ion Cells at Elevated Temperature2017Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    The high voltage spinel LiNi0.5Mn1.5O4 (LNMO) has an average operating potential around 4.7 V vs. Li/Li+ and a gravimetric charge capacity of 146 mAh/g making it a promising high energy density positive electrode for Li-ion batteries. Additionally, the 3-D lithium transport paths available in the spinel structure enables fast diffusion kinetics, making it suitable for power applications [1]. However, the material displays large instability during cycling, especially at elevated temperatures. Therefore, significant research efforts have been undertaken to better understand and improve this electrode material.

    Electrolyte (LiPF6 in organic solvents) oxidation and transition metal dissolution are often considered as the main problems [2] for the systems based on this cathode material. These can cause a variety of problems (in different parts of the cell) eventually increasing internal cell resistance, causing active mass loss and decreasing the amount of cyclable lithium.

    Among these issues, cyclable lithium loss cannot be observed in half cells since lithium metal will provide almost unlimited capacity. Being a promising full cell chemistry for high power applications, there has also been a considerable interest on LNMO full cells with Li4Ti5O12 (LTO) used as the negative electrode. For this chemistry, for an optimized cell, quite stable cycling for >1000 cycles has been reported at room temperature while fast fading is still present at 55 °C [3]. This difference in performance (RT vs. 55 °C) is beyond most expectations and likely does not follow any Arrhenius-type of trend.

    In this study, a comprehensive analysis of LNMO-LTO cells has been performed at different temperatures (RT, 40 °C and 55 °C) to understand the underlying reasons behind stable cycling at room temperature and rapid fading at 55 °C. For this purpose, testing was made on regular cells (Figure 1a), 3-electrode cells (Figure 1b) and back-to-back cells [4] (Figure 1c). Electrode interactions (cross-talk) have been shown to exist in the LTO-LNMO system [5] and back-to-back cells have therefore been used to observe fading under conditions where cross-talk is impossible [4]. Galvanostatic cycling combined with short-duration intermittent current interruptions [6] was performed in order to separately observe changes in internal resistance for LNMO and LTO electrodes in a full cell. Ex-situ characterization of electrodes have also been performed using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and X-ray absorption near edge spectroscopy (XANES).

    Our findings show how important the electrode interactions can be in full cells, as a decrease in lithium inventory was shown to be the major factor for the observed capacity fading at elevated temperature. In this presentation, the effect of other factors – active mass loss and internal cell resistance – will be discussed together with the consequences of cross-talk.

    References

    [1] A. Kraytsberg et al. Adv. Energy Mater., vol. 2, pp. 922–939,2012.

    [2] J. H. Kim et al., ChemPhysChem, vol. 15, pp. 1940–1954, 2014.

    [3] H. M. Wu et al. J. E. Soc., vol. 156, pp. A1047–A1050, 2009.

    [4] S. R. Li et al., J. E. Soc., vol. 160, no. 9, pp. A1524–A1528, 2013.

    [5] Dedryvère et al. J. Phys. C., vol. 114 (24), pp. 10999–11008, 2010.

    [6] M. J. Lacey, ChemElectroChem, pp. 1–9, 2017.

  • 36.
    Aktekin, Burak
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Lacey, Matthew
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Nordh, Tim
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Younesi, Reza
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Tengstedt, Carl
    Scania CV AB.
    Zipprich, Wolfgang
    Volkswagen AG.
    Brandell, Daniel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Understanding the Capacity Loss in LiNi0.5Mn1.5O4 - Li4Ti5O12 Lithium-Ion Cells at Ambient and Elevated Temperatures2017Konferensbidrag (Refereegranskat)
    Abstract [en]

    The high voltage spinel LiNi0.5Mn1.5O(LNMO) is an attractive positive electrode due to its operating voltage around 4.7 V (vs. Li/Li+) arising from the Ni2+/Ni4+ redox couple. In addition to high voltage operation, a second advantage of this material is its capability for fast lithium diffusion kinetics through 3-D transport paths in the spinel structure. However, the electrode material is prone to side reactions with conventional electrolytes, including electrolyte decomposition and transition metal dissolution, especially at elevated temperatures1. It is important to understand how undesired reactions originating from the high voltage spinel affect the aging of different cell components and overall cycle life. Half-cells are usually considered as an ideal cell configuration in order to get information only from the electrode of interest. However, this cell configuration may not be ideal to understand capacity fading for long-term cycling and the assumption of ‘stable’ lithium negative electrode may not be valid, especially at high current rates2. Also, among the variety of capacity fading mechanisms, the loss of “cyclable” lithium from the positive electrode (or gain of lithium from electrolyte into the negative electrode) due to side reactions in a full-cell can cause significant capacity loss. This capacity loss is not observable in a typical half-cell as a result of an excessive reserve of lithium in the negative electrode.

    In a full-cell, it is desired that the negative electrode does not contribute to side reactions in a significant way if the interest is more on the positive side. Among candidates on the negative side, Li4Ti5O12 (LTO) is known for its stability since its voltage plateau (around 1.5 V vs. Li/Li+) is in the electrochemical stability window of standard electrolytes and it shows a very small volume change during lithiation. These characteristics make the LNMO-LTO system attractive for a variety of applications (e.g. electric vehicles) but also make it a good model system for studying aging in high voltage spinel-based full cells.

    In this study, we aim to understand the fundamental mechanisms resulting in capacity fading for LNMO-LTO full cells both at room temperature and elevated temperature (55°C). It is known that electrode interactions occur in this system due to migration of reaction products from LNMO to the LTO side3, 4. For this purpose, three electrode cells have been cycled galvanostatically with short-duration intermittent current interruptionsin order to observe internal resistance for both LNMO and LTO electrodes in a full cell, separately. Change of voltage curves over cycling has also been observed to get an insight into capacity loss. For comparison purposes, back-to-back cells (a combination of LNMO and LTO cells connected electrically by lithium sides) were also tested similarly. Post-cycling of harvested electrodes in half cells was conducted to determine the degree of capacity loss due to charge slippage compared to other aging factors. Surface characterization of LNMO as well as LTO electrodes after cycling at room temperature and elevated temperature has been done via SEM, XPS, HAXPES and XANES.

    References

    1. A. Kraytsberg, Y. Ein-Eli, Adv. Energy Mater., vol. 2, pp. 922–939, 2012.

    2. Aurbach, D., Zinigrad, E., Cohen, Y., & Teller, H. Solid State Ionics, 148(3), 405-416, 2002.

    3. Li et al., Journal of The Electrochemical Society, 160 (9) A1524-A1528, 2013.

    4. Aktekin et al., Journal of The Electrochemical Society 164.4: A942-A948. 2017.

    5. Lacey, M. J., ChemElectroChem. Accepted Author Manuscript. doi:10.1002/celc.201700129, 2017. 

  • 37.
    Aktekin, Burak
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Lacey, Matthew
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Nordh, Tim
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Younesi, Reza
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Tengstedt, Carl
    Scania CV AB.
    Zipprich, Wolfgang
    Volkswagen.
    Brandell, Daniel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Understanding the capacity loss in LNMO-LTO lithium-ion cells at ambient and elevated temperaturesManuskript (preprint) (Övrigt vetenskapligt)
    Abstract
  • 38.
    Aktekin, Burak
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Massel, Felix
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Ahmadi, Majid
    Delft University of Technology, Kavli Institute of Nanoscience, Faculty of Applied Sciences.
    Valvo, Mario
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Hahlin, Maria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Zipprich, Wolfgang
    Volkswagen AG.
    Marzano, Fernanda
    Scania CV AB.
    Duda, Laurent
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Younesi, Reza
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Brandell, Daniel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    How Mn/Ni ordering controls electrochemical performance in high-voltage spinel LiNi0.44Mn1.56O4 (LNMO) with fixed oxygen contentManuskript (preprint) (Övrigt vetenskapligt)
  • 39.
    Aktekin, Burak
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Massel, Felix
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Ahmadi, Majid
    Delft Univ Technol, Fac Appl Sci, Kavli Inst Nanosci, NL-2628 CJ Delft, Netherlands..
    Valvo, Mario
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Hahlin, Maria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Zipprich, Wolfgang
    Volkswagen AG, D-38436 Wolfsburg, Germany..
    Marzano, Fernanda
    Scania CV AB, SE-15187 Sodertalje, Sweden..
    Duda, Laurent
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Molekyl- och kondenserade materiens fysik.
    Younesi, Reza
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Brandell, Daniel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    How Mn/Ni Ordering Controls Electrochemical Performance in High-Voltage Spinel LiNi0.44Mn1.56O4 with Fixed Oxygen Content2020Ingår i: ACS Applied Energy Materials, E-ISSN 2574-0962, Vol. 3, nr 6, s. 6001-6013Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The crystal structure of LiNi0.5O4 (LNMO) can adopt either low-symmetry ordered (Fd (3) over barm) or high-symmetry disordered (P4(3)32) space group depending on the synthesis conditions. A majority of published studies agree on superior electrochemical performance of disordered LNMO, but the underlying reasons for improvement remain unclear due to the fact that different thermal history of the samples affects other material properties such as oxygen content and particle morphology. In this study, ordered and disordered samples were prepared with a new strategy that renders samples with identical properties apart from their cation ordering degree. This was achieved by heat treatment of powders under pure oxygen atmosphere at high temperature with a final annealing step at 710 degrees C for both samples, followed by slow or fast cooling. Electrochemical testing showed that cation disordering improves the stability of material in charged (delithiated) state and mitigates the impedance rise in LNMO parallel to LTO (Li4Ti5O12) and LNMO parallel to Li cells. Through X-ray photoelectron spectroscopy (XPS), thicker surface films were observed on the ordered material, indicating more electrolyte side reactions. The ordered samples also showed significant changes in the Ni 2p XPS spectra, while the generation of ligand (oxygen) holes was observed in the Ni-O environment for both samples using X-ray absorption spectroscopy (XAS) and resonant inelastic X-ray scattering (RIXS). Moreover, high-resolution transmission electron microscopy (HRTEM) images indicated that the ordered samples show a decrease in ordering near the particle surface after cycling and a tendency toward rock-salt-like phase transformations. These results show that the structural arrangement of Mn/Ni (alone) has an effect on the surface and "nearsurface" properties of LNMO, particularly in delithiated state, which is likely connected to the bulk electronic properties of this electrode material.

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    FULLTEXT01
  • 40.
    Aktekin, Burak
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Valvo, Mario
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Smith, Ronald I.
    Rutherford Appleton Lab, ISIS Pulsed Neutron & Muon Source, Harwell Campus, Didcot OX11 0QX, Oxon, England.
    Sörby, Magnus H.
    Inst Energy Technol, Dept Neutron Mat Characterizat, POB 40, NO-2027 Kjeller, Norway.
    Marzano, Fernanda Lodi
    Scania CV AB, SE-15187 Sodertalje, Sweden.
    Zipprich, Wolfgang
    Volkswagen AG, D-38436 Wolfsburg, Germany.
    Brandell, Daniel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Brant, William
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Cation Ordering and Oxygen Release in LiNi0.5-xMn1.5+xO4-y (LNMO): In Situ Neutron Diffraction and Performance in Li Ion Full Cells2019Ingår i: ACS Applied Energy Materials, E-ISSN 2574-0962, Vol. 2, nr 5, s. 3323-3335Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Lithium ion cells utilizing LiNi0.5Mn1.5O4 (LNMO) as the positive electrode are prone to fast capacity fading, especially when operated in full cells and at elevated temperatures. The crystal structure of LNMO can adopt a P4(3)32 (cation-ordered) or Fd (3) over barm (disordered) arrangement, and the fading rate of cells is usually mitigated when samples possess the latter structure. However, synthesis conditions leading to disordering also lead to oxygen deficiencies and rock-salt impurities and as a result generate Mn3+. In this study, in situ neutron diffraction was performed on disordered and slightly Mn-rich LNMO samples to follow cation ordering-disordering transformations during heating and cooling. The study shows for the first time that there is not a direct connection between oxygen release and cation disordering, as cation disordering is observed to start prior to oxygen release when the samples are heated in a pure oxygen atmosphere. This result demonstrates that it is possible to tune disordering in LNMO without inducing oxygen deficiencies or forming the rock-salt impurity phase. In the second part of the study, electrochemical testing of samples with different degrees of ordering and oxygen content has been performed in LNMO vertical bar vertical bar LTO (Li4Ti5O12) full cells. The disordered sample exhibits better performance, as has been reported in other studies; however, we observe that all cells behave similarly during the initial period of cycling even when discharged at a 10 C rate, while differences arise only after a period of cycling. Additionally, the differences in fading rate were observed to be time-dependent rather than dependent on the number of cycles. This performance degradation is believed to be related to instabilities in LNMO at higher voltages, that is, in its lower lithiation states. Therefore, it is suggested that future studies should target the individual effects of ordering and oxygen content. It is also suggested that more emphasis during electrochemical testing should be placed on the stability of samples in their delithiated state.

  • 41.
    Alfakes, Boulos
    et al.
    Khalifa Univ Sci & Technol, LENS, Masdar Campus, Abu Dhabi 54224, U Arab Emirates.;Khalifa Univ Sci & Technol, Dept Mech & Mat Engn, Masdar Campus, Abu Dhabi 54224, U Arab Emirates..
    Garlisi, Corrado
    Khalifa Univ Sci & Technol, Dept Chem Engn, Masdar Campus, Abu Dhabi 54224, U Arab Emirates.;Khalifa Univ Sci & Technol, Res & Innovat CO2 & H2 RICH Ctr, POB 127788, Abu Dhabi, U Arab Emirates..
    Villegas, Juan
    New York Univ, Dept Elect & Comp Engn, Abu Dhabi 129118, U Arab Emirates..
    Al-Hagri, Abdulrahman
    Khalifa Univ Sci & Technol, LENS, Masdar Campus, Abu Dhabi 54224, U Arab Emirates.;Khalifa Univ Sci & Technol, Dept Mech & Mat Engn, Masdar Campus, Abu Dhabi 54224, U Arab Emirates..
    Tamalampudi, Srinivasa
    Khalifa Univ Sci & Technol, LENS, Masdar Campus, Abu Dhabi 54224, U Arab Emirates.;Khalifa Univ Sci & Technol, Dept Mech & Mat Engn, Masdar Campus, Abu Dhabi 54224, U Arab Emirates..
    Rajput, Nitul S.
    Khalifa Univ Sci & Technol, LENS, Masdar Campus, Abu Dhabi 54224, U Arab Emirates.;Khalifa Univ Sci & Technol, Dept Mech & Mat Engn, Masdar Campus, Abu Dhabi 54224, U Arab Emirates..
    Lu, Jin-You
    Khalifa Univ Sci & Technol, LENS, Masdar Campus, Abu Dhabi 54224, U Arab Emirates.;Khalifa Univ Sci & Technol, Dept Mech & Mat Engn, Masdar Campus, Abu Dhabi 54224, U Arab Emirates..
    Lewin, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi.
    Sá, Jacinto
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi. Polish Acad Sci, Inst Phys Chem, PL-01224 Warsaw, Poland..
    Almansouri, Ibraheem
    Khalifa Univ Sci & Technol, LENS, Masdar Campus, Abu Dhabi 54224, U Arab Emirates..
    Palmisano, Giovanni
    Khalifa Univ Sci & Technol, Dept Chem Engn, Masdar Campus, Abu Dhabi 54224, U Arab Emirates.;Khalifa Univ Sci & Technol, Res & Innovat CO2 & H2 RICH Ctr, POB 127788, Abu Dhabi, U Arab Emirates..
    Chiesa, Matteo
    Khalifa Univ Sci & Technol, LENS, Masdar Campus, Abu Dhabi 54224, U Arab Emirates.;Khalifa Univ Sci & Technol, Dept Mech & Mat Engn, Masdar Campus, Abu Dhabi 54224, U Arab Emirates.;UiT Arctic Univ Norway, Dept Phys & Technol, N-9037 Tromso, Norway..
    Enhanced photoelectrochemical performance of atomic layer deposited Hf-doped ZnO2020Ingår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 385, artikel-id 125352Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Generation of hydrogen using photoelectrochemical (PEC) water splitting has attracted researchers for the last two decades. Several materials have been utilized as a photoanode in a water splitting cell, including ZnO due to its abundance, low production cost and suitable electronic structure. Most research attempts focused on doping ZnO to tailor its properties for a specific application. In this work, atomic layer deposition (ALD) was used to precisely dope ZnO with hafnium (Hf) in order to enhance its PEC performance. The resultant doped materials showed a significant improvement in PEC efficiency compared to pristine ZnO, which is linked directly to Hf introduction revealed by detailed optical, structural and electrical analyses. The photocurrent obtained in the best performing Hf-doped sample (0.75 wt% Hf) was roughly threefold higher compared to the undoped ZnO. Electrochemical impedance spectroscopy (EIS) and open-circuit potential-decay (OCPD) measurements confirmed suppression in photocarriers' surface recombination in the doped films, which led to a more efficient PEC water oxidation. The enhanced PEC performance of Hf-doped ZnO and effectiveness of the used metal dopant are credited to the synergistic optimization of chemical composition, which enhanced the electrical, structural including morphological, and optical properties of the final material, making Hf-doping an attractive candidate for novel PEC electrodes.

  • 42.
    Alfredsson, Sara
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Varför svänger stenen?: En studie i curlingens komplexa tribosystem2010Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The tribo system ice-curling stone was investigated in order to understand the mechanisms behind the stones' behavior on the ice sheet. The problem with non-identical stones should also be addressed.The stone curls, that is, its sliding path deviates from a straight line to the right for a clock-wise rotation and to the left for a anti-clock-wise rotation. Several mechanisms to explain this behavior have been proposed over the years but none has been successful.By carrying out experiments at the local curling rink and studying silicon castings of ice- and stone-surfaces with scanning electron microscopy and vertical scanning interferometry, it has been decided that the curl is not due to dry friction, ice-debris or the difference in friction on the left and right side of the stone. The side force comes from the fact that the friction is higher at the back of the stone than at the front.The contact between stone and ice is never completely dry, nor in the hydrodynamic lubrication regime. It is probably a combination of hydrodynamic lubrication and a contribution from mechanical scratching of the ice. The coefficient of friction depends upon the velocity, from 0.01 for velocities around 1 m/s to higher values for lower velocities. It is not possible to make identical stones, that is identical glide band structures out of Blue Hone granite, since its composition is too inhomogeneous and its grain size is too course. It is recommended to use an amorphous or very fine grained material, at least in the surface of the glideband.

    Ladda ner fulltext (pdf)
    fulltext
  • 43.
    Alharbi, Essa A.
    et al.
    Ecole Polytech Fed Lausanne, Lab Photon & Interfaces, Inst Chem Sci & Engn, Sch Basic Sci, CH-1015 Lausanne, Switzerland..
    Baumeler, Thomas P.
    Ecole Polytech Fed Lausanne, Lab Photon & Interfaces, Inst Chem Sci & Engn, Sch Basic Sci, CH-1015 Lausanne, Switzerland..
    Krishna, Anurag
    Ecole Polytech Fed Lausanne, Lab Photomol Sci, Inst Chem Sci & Engn, Sch Basic Sci, CH-1015 Lausanne, Switzerland..
    Alyamani, Ahmed Y.
    Natl Ctr Nanotechnol King Abdulaziz City Sci & Te, Riyadh 11442, Saudi Arabia..
    Eickemeyer, Felix T.
    Ecole Polytech Fed Lausanne, Lab Photon & Interfaces, Inst Chem Sci & Engn, Sch Basic Sci, CH-1015 Lausanne, Switzerland..
    Ouellette, Olivier
    Ecole Polytech Fed Lausanne, Lab Photon & Interfaces, Inst Chem Sci & Engn, Sch Basic Sci, CH-1015 Lausanne, Switzerland..
    Pan, Linfeng
    Ecole Polytech Fed Lausanne, Lab Photomol Sci, Inst Chem Sci & Engn, Sch Basic Sci, CH-1015 Lausanne, Switzerland..
    Alghamdi, Fahad S.
    Natl Ctr Nanotechnol King Abdulaziz City Sci & Te, Riyadh 11442, Saudi Arabia..
    Wang, Zaiwei
    Ecole Polytech Fed Lausanne, Lab Photomol Sci, Inst Chem Sci & Engn, Sch Basic Sci, CH-1015 Lausanne, Switzerland..
    Alotaibi, Mohammad Hayal
    Natl Ctr Nanotechnol King Abdulaziz City Sci & Te, Riyadh 11442, Saudi Arabia..
    Yang, Bowen
    Ecole Polytech Fed Lausanne, Lab Photomol Sci, Inst Chem Sci & Engn, Sch Basic Sci, CH-1015 Lausanne, Switzerland..
    Almalki, Masaud
    Ecole Polytech Fed Lausanne, Lab Photon & Interfaces, Inst Chem Sci & Engn, Sch Basic Sci, CH-1015 Lausanne, Switzerland..
    Mensi, Mounir D.
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn ISIC, CH-1950 Sion, Switzerland..
    Albrithen, Hamad
    Natl Ctr Nanotechnol King Abdulaziz City Sci & Te, Riyadh 11442, Saudi Arabia.;KA CARE Energy Res & Innovat Ctr Riyadh, Riyadh, Saudi Arabia.;King Saud Univ, Lab Appl Sensing Res, King Abdullah Inst Nanotechnol Aramco, Riyadh 11451, Saudi Arabia.;King Saud Univ, Coll Sci, Dept Phys & Astron, Res Chair Tribol Surface & Interface Sci, Riyadh 11451, Saudi Arabia..
    Albadri, Abdulrahman
    Natl Ctr Nanotechnol King Abdulaziz City Sci & Te, Riyadh 11442, Saudi Arabia..
    Hagfeldt, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi. Ecole Polytech Fed Lausanne, Lab Photomol Sci, Inst Chem Sci & Engn, Sch Basic Sci, CH-1015 Lausanne, Switzerland..
    Zakeeruddin, Shaik M.
    Ecole Polytech Fed Lausanne, Lab Photon & Interfaces, Inst Chem Sci & Engn, Sch Basic Sci, CH-1015 Lausanne, Switzerland..
    Gratzel, Michael
    Ecole Polytech Fed Lausanne, Lab Photon & Interfaces, Inst Chem Sci & Engn, Sch Basic Sci, CH-1015 Lausanne, Switzerland..
    Formation of High-Performance Multi-Cation Halide Perovskites Photovoltaics by delta-CsPbI3/delta-RbPbI3 Seed-Assisted Heterogeneous Nucleation2021Ingår i: Advanced Energy Materials, ISSN 1614-6832, E-ISSN 1614-6840, Vol. 11, nr 16, artikel-id 2003785Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The performance of perovskite solar cells is highly dependent on the fabrication method; thus, controlling the growth mechanism of perovskite crystals is a promising way towards increasing their efficiency and stability. Herein, a multi-cation halide composition of perovskite solar cells is engineered via the two-step sequential deposition method. Strikingly, it is found that adding mixtures of 1D polymorphs of orthorhombic delta-RbPbI3 and delta-CsPbI3 to the PbI2 precursor solution induces the formation of porous mesostructured hexagonal films. This porosity greatly facilitates the heterogeneous nucleation and the penetration of FA (formamidinium)/MA (methylammonium) cations within the PbI2 film. Thus, the subsequent conversion of PbI2 into the desired multication cubic alpha-structure by exposing it to a solution of formamidinium methylammonium halides is greatly enhanced. During the conversion step, the delta-CsPbI3 also is fully integrated into the 3D mixed cation perovskite lattice, which exhibits high crystallinity and superior optoelectronic properties. The champion device shows a power conversion efficiency (PCE) over 22%. Furthermore, these devices exhibit enhanced operational stability, with the best device retaining more than 90% of its initial value of PCE under 1 Sun illumination with maximum power point tracking for 400 h.

  • 44.
    Aliramaji, Shamsa
    et al.
    Rhein Westfal TH Aachen, Mat Chem, Kopernikusstr 10, D-52074 Aachen, Germany..
    Keuter, Philipp
    Rhein Westfal TH Aachen, Mat Chem, Kopernikusstr 10, D-52074 Aachen, Germany..
    Neuss, Deborah
    Rhein Westfal TH Aachen, Mat Chem, Kopernikusstr 10, D-52074 Aachen, Germany..
    Hans, Marcus
    Rhein Westfal TH Aachen, Mat Chem, Kopernikusstr 10, D-52074 Aachen, Germany..
    Primetzhofer, Daniel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Tillämpad kärnfysik.
    Depla, Diederik
    Univ Ghent, Dept Solid State Sci, Krijgslaan 281 S1, B-9000 Ghent, Belgium..
    Schneider, Jochen M.
    Rhein Westfal TH Aachen, Mat Chem, Kopernikusstr 10, D-52074 Aachen, Germany..
    Effect of Growth Temperature and Atmosphere Exposure Time on Impurity Incorporation in Sputtered Mg, Al, and Ca Thin Films2023Ingår i: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 16, nr 1, artikel-id 414Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Impurities can be incorporated during thin film deposition, but also can originate from atmosphere exposure. As impurities can strongly affect the composition-structure-property relations in magnetron sputter deposited thin films, it is important to distinguish between both incorporation channels. Therefore, the impurity incorporation by atmosphere exposure into sputtered Mg, Al, and Ca thin films is systematically studied by a variation of the deposition temperatures and atmosphere exposure times. Deposition temperature variation results in morphological modifications explained by considering surface and bulk diffusion as well as grain boundary motion and evaporation. The film morphologies exhibiting the lowest oxygen concentrations, as measured by energy dispersive X-ray spectroscopy, are obtained at a homologous temperature of 0.4 for both Mg and Al thin films. For Ca, preventing atmosphere exposure is essential to hinder impurity incorporation: By comparing the impurity concentration in Al-capped and uncapped thin films, it is demonstrated that Ca thin films are locally protected by Al-capping, while Mg (and Al) form native passivation layers. Furthermore, it can be learned that the capping (or self-passivation) efficiency in terms of hindering further oxidation of the films in atmosphere is strongly dependent on the underlying morphology, which in turn is defined by the growth temperature.

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  • 45.
    Alvarez, Sol Gutierrez
    et al.
    Tech Univ Denmark, Dept Chem, DK-2800 Lyngby, Denmark..
    Lin, Weihua
    Lund Univ, Dept Chem Phys, S-22100 Lund, Sweden.;Lund Univ, NanoLund Chem Ctr, S-22100 Lund, Sweden..
    Abdellah, Mohamed
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Meng, Jie
    Tech Univ Denmark, Dept Chem, DK-2800 Lyngby, Denmark..
    Zidek, Karel
    Czech Acad Sci, Vvi, Inst Plasma Phys, Res Ctr Special Opt & Optoelect Syst TOPTEC, Prague 18200 8, Czech Republic..
    Pullerits, Tönu
    Lund Univ, Dept Chem Phys, S-22100 Lund, Sweden.;Lund Univ, NanoLund Chem Ctr, S-22100 Lund, Sweden..
    Zheng, Kaibo
    Tech Univ Denmark, Dept Chem, DK-2800 Lyngby, Denmark.;Lund Univ, Dept Chem Phys, S-22100 Lund, Sweden.;Lund Univ, NanoLund Chem Ctr, S-22100 Lund, Sweden..
    Charge Carrier Diffusion Dynamics in Multisized Quaternary Alkylammonium-Capped CsPbBr3 Perovskite Nanocrystal Solids2021Ingår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 13, nr 37, s. 44742-44750Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    CsPbBr3 quantum dots (QDs) are promising candidates for optoelectronic devices. The substitution of oleic acid ( OA) and oleylamine ( OLA) capping agents with a quaternary alkylammonium such as di-dodecyl dimethyl ammonium bromide (DDAB) has shown an increase in external quantum efficiency (EQE) from 0.19% (OA/OLA) to 13.4% (DDAB) in LED devices. The device performance significantly depends on both the diffusion length and the mobility of photoexcited charge carriers in QD solids. Therefore, we investigated the charge carrier transport dynamics in DDAB-capped CsPbBr3 QD solids by constructing a bi-sized QD mixture film. Charge carrier diffusion can be monitored by quantitatively varying the ratio between two sizes of QDs, which varies the mean free path of the carriers in each QD cluster. Excited-state dynamics of the QD solids obtained from ultrafast transient absorption spectroscopy reveals that the photogenerated electrons and holes are difficult to diffuse among small-sized QDs (4 nm) due to the strong quantum confinement. On the other hand, both photoinduced electrons and holes in large-sized QDs (10 nm) would diffuse toward the interface with the small-sized QDs, followed by a recombination process. Combining the carrier diffusion study with a Monte Carlo simulation on the QD assembly in the mixture films, we can calculate the diffusion lengths of charge carriers to be similar to 239 +/- 16 nm in 10 nm CsPbBr3 QDs and the mobility values of electrons and holes to be 2.1 (+/- 0.1) and 0.69 (+/- 0.03) cm(2)/V s, respectively. Both parameters indicate an efficient charge carrier transport in DDAB-capped QD films, which rationalized the perfect performance of their LED device application.

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  • 46.
    Ammothum Kandy, Akshay Krishna
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Linear models for multiscale materials simulations: Towards a seamless linking of electronic and atomistic models for complex metal oxides2021Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Multiscale modelling approaches, connecting data from electronic structure calculations all the way towards engineering continuum models, have become an important ingredient in modern materials science. Materials modelling in a broader sense is already amply used to address complex chemical problems in academic science, but also in many industrial sectors. As far as multiscale modelling is concerned, however, many challenges remain, in particular when it comes to coupling and linking the various levels along the multiscale ladder in a seamless and efficient fashion.        

    This thesis focusses on the development of new and efficient linear models to improve the quality and parameterisation processes of the two-body potentials used in empirical and semi-empirical methods within a multiscale materials modelling framework. In this regard, a machinery called curvature constrained splines (CCS) based on cubic splines to approximate general two-body potentials has been developed. The method is linear, and parameters can be easily solved in a least-square sense using a quadratic programming approach. Moreover, the objective function is  convex, implying that global minima can be readily found. This makes the optimisation process easy to handle and requires little to no human effort. Initial tests to validate the method were performed on molecular and bulk neon systems. Later, the method was extended to incorporate long-range interactions by including atomic charges. The capability of the method was demonstrated for ZnO polymorphs, and at the same time benchmarked towards the conventional  Buckingham potentials applied to the same problem. The results indicate that the CCS+Q method performs on par with the Buckingham approach, but is much faster and easier to parameterise. The merits of the method is further demonstrated with an exploration of size and shape dependent stability of CeO2 nanoparticles.

    Having established the framework of the CCS methodology, the method was further used to develop repulsive potentials for the semi-empirical self-consistent charge density functional tight binding (SCC-DFTB) method. The generation of the repulsive potentials is normally a tedious and time-consuming task. The  CCS methodology  makes this process significantly more efficient, and further provides new opportunities to explore the limits of the SCC-DFTB method. The development of repulsive potentials for bulk Si polymorphs showed that it is possible to retrieve a good description of each individual polymorph, but impossible to obtain an acceptable joint description of all polymorphs. The results indicated that a transferable repulsive potential needs to have coordination dependence, and by the  use of a many-body artificial neural network representation for the repulsive potential, it was indeed possible to obtain a global transferability. The CCS methodology was finally used to model a system of considerable chemical diversity and complexity, namely reduced CeO2 within the SCC-DFTB formalism. Here, the CCS framework facilitated the development of an efficient workflow that yielded a harmonized description of Ce ions in different oxidation states. In short, the introduced CCS-based workflow proved to extend the applicability of SCC-DFTB to complex oxide systems with correlated electronic states.               

    To conclude, the CCS methodology is demonstrated to be a versatile tool for efficient linking between (and within) electronic and atomistic models.

    Delarbeten
    1. CCS: A software framework to generate two-body potentials using Curvature Constrained Splines
    Öppna denna publikation i ny flik eller fönster >>CCS: A software framework to generate two-body potentials using Curvature Constrained Splines
    Visa övriga...
    2021 (Engelska)Ingår i: Computer Physics Communications, ISSN 0010-4655, E-ISSN 1879-2944, Vol. 258, artikel-id 107602Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    We have developed an automated and efficient scheme for the fitting of data using Curvature Constrained Splines (CCS), to construct accurate two-body potentials. The approach enabled the construction of an oscillation-free, yet flexible, potential. We show that the optimization problem is convex and that it can be reduced to a standard Quadratic Programming (QP) problem. The improvements are demonstrated by the development of a two-body potential for Ne from ab initio data. We also outline possible extensions to the method. Program summary Program Title: CCS CPC Library link to program files: http://dx.doi.org/10.17632/7dt5nzxgbs.1 Developer's repository link:gttp://github.com/aksam432/CCS Licensing provisions: GPLv3 Programming language: Python External routines/libraries: NumPy, matplotlib, ASE, CVXOPT Nature of problem: Ab initio quantum chemistry methods are often computationally very expensive. To alleviate this problem, the development of efficient empirical and semi-empirical methods is necessary. Two-body potentials are ubiquitous in empirical and semi-empirical methods. Solution method: The CCS package provides a new strategy to obtain accurate two body potentials. The potentials are described as cubic splines with curvature constraints.

    Ort, förlag, år, upplaga, sidor
    ElsevierELSEVIER, 2021
    Nyckelord
    Two-body potential, Force field, Quadratic programming, Cubic splines, Python
    Nationell ämneskategori
    Datavetenskap (datalogi) Den kondenserade materiens fysik
    Identifikatorer
    urn:nbn:se:uu:diva-426306 (URN)10.1016/j.cpc.2020.107602 (DOI)000587360000039 ()
    Forskningsfinansiär
    VetenskapsrådeteSSENCE - An eScience Collaboration
    Tillgänglig från: 2020-11-30 Skapad: 2020-11-30 Senast uppdaterad: 2024-01-15Bibliografiskt granskad
    2. Development of efficient linearly parametrized force fields for ionic materials
    Öppna denna publikation i ny flik eller fönster >>Development of efficient linearly parametrized force fields for ionic materials
    (Engelska)Ingår i: Artikel i tidskrift (Övrigt vetenskapligt) In press
    Nationell ämneskategori
    Naturvetenskap
    Identifikatorer
    urn:nbn:se:uu:diva-434542 (URN)
    Tillgänglig från: 2021-02-10 Skapad: 2021-02-10 Senast uppdaterad: 2021-02-10
    3. Curvature Constrained Splines for DFTB Repulsive Potential Parametrization
    Öppna denna publikation i ny flik eller fönster >>Curvature Constrained Splines for DFTB Repulsive Potential Parametrization
    Visa övriga...
    2021 (Engelska)Ingår i: Journal of Chemical Theory and Computation, ISSN 1549-9618, E-ISSN 1549-9626, Vol. 17, nr 3, s. 1771-1781Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    The Curvature Constrained Splines (CCS) methodology has been used for fitting repulsive potentials to be used in SCC-DFTB calculations. The benefit of using CCS is that the actual fitting of the repulsive potential is performed through quadratic programming on a convex objective function. This guarantees a unique (for strictly convex) and optimum two-body repulsive potential in a single shot, thereby making the parametrization process robust, and with minimal human effort. Furthermore, the constraints in CCS give the user control to tune the shape of the repulsive potential based on prior knowledge about the system in question. Herein, we developed the method further with new constraints and the capability to handle sparse data. We used the method to generate accurate repulsive potentials for bulk Si polymorphs and demonstrate that for a given Slater-Koster table, which reproduces the experimental band structure for bulk Si in its ground state, we are unable to find one single two-body repulsive potential that can accurately describe the various bulk polymorphs of silicon in our training set. We further demonstrate that to increase transferability, the repulsive potential needs to be adjusted to account for changes in the chemical environment, here expressed in the form of a coordination number. By training a near-sighted Atomistic Neural Network potential, which includes many-body effects but still essentially within the first-neighbor shell, we can obtain full transferability for SCC-DFTB in terms of describing the energetics of different Si polymorphs.

    Ort, förlag, år, upplaga, sidor
    American Chemical Society (ACS), 2021
    Nationell ämneskategori
    Materialkemi
    Identifikatorer
    urn:nbn:se:uu:diva-434543 (URN)10.1021/acs.jctc.0c01156 (DOI)000629135700038 ()33606527 (PubMedID)
    Forskningsfinansiär
    VetenskapsrådeteSSENCE - An eScience CollaborationSwedish National Infrastructure for Computing (SNIC)Deutsche Forschungsgemeinschaft (DFG), RTG 2247
    Tillgänglig från: 2021-02-10 Skapad: 2021-02-10 Senast uppdaterad: 2024-01-15Bibliografiskt granskad
    4. Accurate description of Ce 4f states in reduced ceria using SCC-DFTB+U simulations
    Öppna denna publikation i ny flik eller fönster >>Accurate description of Ce 4f states in reduced ceria using SCC-DFTB+U simulations
    (Engelska)Ingår i: Artikel i tidskrift (Övrigt vetenskapligt) In press
    Nationell ämneskategori
    Materialkemi
    Identifikatorer
    urn:nbn:se:uu:diva-434544 (URN)
    Tillgänglig från: 2021-02-10 Skapad: 2021-02-10 Senast uppdaterad: 2021-02-10
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    presentationsbild
  • 47.
    Ammothum Kandy, Akshay Krishna
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Wadbro, Eddie
    Aradi, Bálint
    Broqvist, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Kullgren, Jolla
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Curvature Constrained Splines for DFTB Repulsive Potential Parametrization2021Ingår i: Journal of Chemical Theory and Computation, ISSN 1549-9618, E-ISSN 1549-9626, Vol. 17, nr 3, s. 1771-1781Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Curvature Constrained Splines (CCS) methodology has been used for fitting repulsive potentials to be used in SCC-DFTB calculations. The benefit of using CCS is that the actual fitting of the repulsive potential is performed through quadratic programming on a convex objective function. This guarantees a unique (for strictly convex) and optimum two-body repulsive potential in a single shot, thereby making the parametrization process robust, and with minimal human effort. Furthermore, the constraints in CCS give the user control to tune the shape of the repulsive potential based on prior knowledge about the system in question. Herein, we developed the method further with new constraints and the capability to handle sparse data. We used the method to generate accurate repulsive potentials for bulk Si polymorphs and demonstrate that for a given Slater-Koster table, which reproduces the experimental band structure for bulk Si in its ground state, we are unable to find one single two-body repulsive potential that can accurately describe the various bulk polymorphs of silicon in our training set. We further demonstrate that to increase transferability, the repulsive potential needs to be adjusted to account for changes in the chemical environment, here expressed in the form of a coordination number. By training a near-sighted Atomistic Neural Network potential, which includes many-body effects but still essentially within the first-neighbor shell, we can obtain full transferability for SCC-DFTB in terms of describing the energetics of different Si polymorphs.

    Ladda ner fulltext (pdf)
    fulltext
  • 48.
    Amombo Noa, Francoise M.
    et al.
    Chalmers Univ Technol, Dept Chem & Chem Engn, Div Chem & Biochem, S-41296 Gothenburg, Sweden..
    Abrahamsson, Maria
    Chalmers Univ Technol, Dept Chem & Chem Engn, Div Chem & Biochem, S-41296 Gothenburg, Sweden..
    Ahlberg, Elisabet
    Univ Gothenburg, Dept Chem & Mol Biol, S-40530 Gothenburg, Sweden..
    Cheung, Ocean
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för materialvetenskap, Nanoteknologi och funktionella material.
    Göb, Christian R.
    Rigaku Europe SE, Hugenottenallee 167, D-63263 Neu Isenburg, Germany..
    McKenzie, Christine J.
    Univ Southern Denmark, Dept Phys Chem & Pharm, Campusvej 55, DK-5230 Odense M, Denmark..
    Öhrström, Lars
    Chalmers Univ Technol, Dept Chem & Chem Engn, Div Chem & Biochem, S-41296 Gothenburg, Sweden..
    A unified topology approach to dot-, rod-, and sheet-MOFs2021Ingår i: Chem, ISSN 2451-9308, E-ISSN 2451-9294, Vol. 7, nr 9, s. 2491-2512Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Metal-organic frameworks made from multi-metal-ion units in the shape of clusters and rods (termed dot-MOFs and rod-MOFs) are well known. Here, we introduce MOFs with multi-metallic units in the form of sheets—sheet-MOFs. We show exemplars of all three types of units based on structures containing Y3+, Ce3+, or Gd3+ linked by benzene-1,2,4,5-tetracarboxylate to give crystals of a dot-MOF in H2NMe2[Y(btec)(H2O)] CTH-14, a sheet-MOF in [Ce3(btec)(Hbtec)(OAc)(HCO2)] CTH-15, and a rod-MOF in 4,4′-azopyridinium[Gd2(btec)2] CTH-16. Cyclic voltammetry shows that CTH-15 stabilizes Ce(IV). Given the fact that sheet-MOFs represent an intellectual advance in the evolution of MOFs, a unified approach is proposed for the topological classification of dot-, rod-, and sheet-MOFs. It is suggested that the stability of MOFs follow in the trend dot < rod < sheet. For CTH-14-16, the sheet- and the rod-MOF have higher thermal stability. We suggest sheet-MOFs as an additional strategy for making robust MOFs.

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  • 49.
    Amombo Noa, Francoise M.
    et al.
    Chalmers Univ Technol, Dept Chem & Chem Engn, Chem & Biochem, SE-41296 Gothenburg, Sweden.
    Svensson Grape, Erik
    Stockholm Univ, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden.
    Brülls, Steffen Marc
    Chalmers Univ Technol, Dept Chem & Chem Engn, Chem & Biochem, SE-41296 Gothenburg, Sweden.
    Cheung, Ocean
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för materialvetenskap, Nanoteknologi och funktionella material.
    Malmberg, Per
    Chalmers Univ Technol, Dept Chem & Chem Engn, Chem & Biochem, SE-41296 Gothenburg, Sweden.
    Inge, A. Ken
    Stockholm Univ, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden.
    McKenzie, Christine J.
    Univ Southern Denmark, Dept Phys Chem & Pharm, DK-5230 Odense M, Denmark.
    Mårtensson, Jerker
    Chalmers Univ Technol, Dept Chem & Chem Engn, Chem & Biochem, SE-41296 Gothenburg, Sweden.
    Öhrström, Lars
    Chalmers Univ Technol, Dept Chem & Chem Engn, Chem & Biochem, SE-41296 Gothenburg, Sweden.
    Metal-Organic Frameworks with Hexakis(4-carboxyphenyl)benzene: Extensions to Reticular Chemistry and Introducing Foldable Nets2020Ingår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 142, nr 20, s. 9471-9481Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nine metal–organic frameworks have been prepared with the hexagon-shaped linker 1,2,3,4,5,6-hexakis(4-carboxyphenyl)benzene (H6cpb) by solvothermal reactions in dimethylformamide (dmf) or dimethylacetamide (dmac) with acetic acid or formic acid as modulators: [Bi2(cpb)(acetato)2(dmf)2]·2dmf CTH-6 forms a rtl-net; 2(H2NMe2)[Cu2(cpb)] CTH-7 forms a kgd-net; [Fe4(cpb)(acetato)2(dmf)4] CTH-8 and [Co4(cpb)(acetato)2(dmf)4] CTH-9 are isostructural and form yav-nets; 2(HNEt3)[Fe2(cpb)] CTH-10 and the two polymorphs of 2(H2NMe2)[Zn2(cpb)]·1.5dmac, Zn-MOF-888 and CTH-11, show kgd-nets; [Cu2(cpb)(acetato)2(dmf)2]·2dmf, CTH-12, forms a mixed coordination and hydrogen-bonded sql-net; and 2(H2NMe2)[Zn2(cpb)] CTH-13, a similarly mixed yav-net. Surface area values (Brunauer–Emmett–Teller, BET) range from 34 m2 g–1 for CTH-12 to 303 m2 g–1 for CTH-9 for samples activated at 120 °C in dynamic vacuum. All compounds show normal (10-fold higher) molar CO2 versus N2 uptake at 298 K, except the 19-fold CO2 uptake for CTH-12 containing Cu(II) dinuclear paddle-wheels. We also show how perfect hexagons and triangles can combine to a new 3D topology laf, a model of which gave us the idea of foldable network topologies, as the laf-net can fold into a 2D form while retaining the local geometry around each vertex. Other foldable nets identified are cds, cds-a, ths, sqc163, clh, jem, and tfc covering the basic polygons and their combinations. The impact of this concept on “breathing” MOFs is discussed. I2 sorption, both from gas phase and from MeOH solution, into CTH-7 were studied by time of flight secondary ion mass spectrometry (ToF-SIMS) on dried crystals. I2 was shown to have penetrated the crystals, as layers were consecutively peeled off by the ion beam. We suggest ToF-SIMS to be a method for studying sorption depth profiles of MOFs.

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  • 50.
    Amorim, Rodrigo G.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori. Univ Fed Fluminense, Dept Fis, ICEx, Volta Redonda, RJ, Brazil..
    Rocha, Alexandre R.
    Univ Estadual Paulista, UNESP, Inst Fis Teor, Sao Paulo, Brazil..
    Scheicher, Ralph H.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialteori.
    Boosting DNA Recognition Sensitivity of Graphene Nanogaps through Nitrogen Edge Functionalization2016Ingår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 120, nr 34, s. 19384-19388Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    One of the challenges for next generation DNA sequencing is to have a robust, stable, and reproducible nanodevice. In this work, we propose how to improve the sensing of DNA nucleobase using functionalized graphene nanogap as a solid state device. Two types of edge functionalization, namely, either hydrogen or nitrogen, were considered. We showed that, independent of species involved in the edge passivation, the highest-to-lowest order of the nucleobase transmissions is not altered, but the intensity is affected by several orders of magnitude. Our results show that nitrogen edge tends to p-dope graphene, and most importantly, it contributes with resonance states close to the Fermi level, which can be associated with the increased conductance. Finally, the translocation process of nucleobases passing through the nanogap was also investigated by varying their position from a certain height (from +3 to -3 angstrom) with respect to the graphene sheet to show that nitrogen-terminated sheets have enhanced sensitivity, as moving the nucleobase by approximately 1 angstrom reduces the conductance by up to 3 orders of magnitude.

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