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  • 101. Boye, S.A
    et al.
    Lazor, P
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Ahuja, R
    Physics, Department of Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Magnetoresistance and Hall effect measurements of Ni to 6 GPa2005In: Journal of Magnetism and Magnetic Materials, Vol. 294, p. 347-358Article in journal (Refereed)
  • 102.
    Boye, S.A
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Lazor, P
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Ahuja, R
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Magnetoresistance and Hall-effect measurements of Ni thin films2005In: Journal of Applied Physics, Vol. 97, p. 083902:1-5Article in journal (Refereed)
  • 103.
    Callini, Elsa
    et al.
    EPFL Valais Wallis Swiss Fed Inst Technol, LMER, Rue Ind 17, CH-1950 Sion, Switzerland.;Swiss Fed Lab Mat Sci & Technol, Empa, Ueberlandstr 129, CH-8600 Dubendorf, Switzerland..
    Aguey-Zinsou, Kondo-Francois
    Univ New S Wales, Sch Chem Engn, MERLin Grp, Sydney, NSW 2052, Australia..
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Royal Inst Technol KTH, Dept Mat & Engn, Appl Mat Phys, S-10044 Stockholm, Sweden..
    Ramon Ares, Jose
    Univ Autonoma Madrid, Fac Ciencias, Dpto Fis Mat, Grp Mire, E-28049 Madrid, Spain..
    Bals, Sara
    Univ Antwerp, Dept Phys, EMAT, Groenenborgerlaan 171, B-2020 Antwerp, Belgium..
    Biliskov, Nikola
    Rudjer Boskovic Inst, Bijenicka Cesta 54, Zagreb 10000, Croatia..
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Charalambopoulou, Georgia
    Natl Ctr Sci Res Demokritos, Athens 15341, Greece..
    Chaudhary, Anna-Lisa
    Helmholtz Zentrum Geesthacht, Inst Mat Res, Dept Nanotechnol, Max Planck Str 1, Geesthacht, Germany..
    Cuevas, Fermin
    UPEC, CNRS, ICMPE, UMR7182, 2-8 Rue Henri Dunant, F-94320 Thiais, France..
    Dam, Bernard
    Delft Univ Technol, Chem Engn, Julianalaan 136, NL-2628 BL Delft, Netherlands..
    de Jongh, Petra
    Univ Utrecht, Debye Inst Nanomat Sci, Inorgan Chem & Catalysis, Univ Weg 99, NL-3584 CG Utrecht, Netherlands..
    Dornheim, Martin
    Helmholtz Zentrum Geesthacht, Inst Mat Res, Dept Nanotechnol, Max Planck Str 1, Geesthacht, Germany..
    Filinchuk, Yaroslav
    Catholic Univ Louvain, Inst Condensed Matter & Nanosci, B-1348 Louvain, Belgium..
    Novakovic, Jasmina Grbovic
    Univ Belgrade, Vinca Inst Nucl Sci, POB 522, Belgrade 1000, Serbia..
    Hirscher, Michael
    Max Planck Inst Intelligent Syst Stuttgart, Heisenbergstr 3, D-70569 Stuttgart, Germany..
    Jensen, Torben R.
    Aarhus Univ, Dept Chem, Ctr Mat Crystallog, Langelandsgade 140, DK-8000 Aarhus C, Denmark.;Aarhus Univ, iNANO, Langelandsgade 140, DK-8000 Aarhus C, Denmark..
    Jensen, Peter Bjerre
    Tech Univ Denmark, Dept Energy Convers & Storage, Fysikvej,Bldg 309, DK-2800 Lyngby, Denmark..
    Novakovic, Nikola
    Univ Belgrade, Vinca Inst Nucl Sci, POB 522, Belgrade 1000, Serbia..
    Lai, Qiwen
    Univ New S Wales, Sch Chem Engn, MERLin Grp, Sydney, NSW 2052, Australia..
    Leardini, Fabrice
    Univ Autonoma Madrid, Fac Ciencias, Dpto Fis Mat, Grp Mire, E-28049 Madrid, Spain..
    Gattia, Daniele Mirabile
    Res Ctr Casaccia, ENEA, Dept Phys Methods & Mat, Via Anguillarese 301, Rome, Italy..
    Pasquini, Luca
    Alma Mater Studiorum Univ Bologna, Dept Phys & Astron, I-40127 Bologna, Italy..
    Steriotis, Theodore
    Natl Ctr Sci Res Demokritos, Athens 15341, Greece..
    Turner, Stuart
    Univ Antwerp, Dept Phys, EMAT, Groenenborgerlaan 171, B-2020 Antwerp, Belgium..
    Vegge, Tejs
    Tech Univ Denmark, Dept Energy Convers & Storage, Fysikvej,Bldg 309, DK-2800 Lyngby, Denmark..
    Zuttel, Andreas
    EPFL Valais Wallis Swiss Fed Inst Technol, LMER, Rue Ind 17, CH-1950 Sion, Switzerland..
    Montone, Amelia
    Res Ctr Casaccia, ENEA, Dept Phys Methods & Mat, Via Anguillarese 301, Rome, Italy..
    Nanostructured materials for solid-state hydrogen storage: A review of the achievement of COST Action MP11032016In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 41, no 32, p. 14404-14428Article in journal (Refereed)
    Abstract [en]

    In the framework of the European Cooperation in Science and Technology (COST) Action MP1103 Nanostructured Materials for Solid-State Hydrogen Storage were synthesized, characterized and modeled. This Action dealt with the state of the art of energy storage and set up a competitive and coordinated network capable to define new and unexplored ways for Solid State Hydrogen Storage by innovative and interdisciplinary research within the European Research Area. An important number of new compounds have been synthesized: metal hydrides, complex hydrides, metal halide ammines and amidoboranes. Tuning the structure from bulk to thin film, nanoparticles and nanoconfined composites improved the hydrogen sorption properties and opened the perspective to new technological applications. Direct imaging of the hydrogenation reactions and in situ measurements under operando conditions have been carried out in these studies. Computational screening methods allowed the prediction of suitable compounds for hydrogen storage and the modeling of the hydrogen sorption reactions on mono-, bi-, and three-dimensional systems. This manuscript presents a review of the main achievements of this Action.

  • 104.
    Chafai, A.
    et al.
    Univ Moulay Ismail, Phys Dept, Fac Sci, Unite Associee CNRST URAC 08,LP2MS, Meknes, Morocco..
    Dujardin, F.
    Univ Lorraine, LCP A2MC, Inst Chim Phys & Mat, 1 Bd Arago, F-57070 Metz, France..
    Essaoudi, I.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Univ Moulay Ismail, Phys Dept, Fac Sci, Unite Associee CNRST URAC 08,LP2MS, Meknes, Morocco.
    Ainane, A.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Univ Moulay Ismail, Phys Dept, Fac Sci, Unite Associee CNRST URAC 08,LP2MS, Meknes, Morocco.;Univ Lorraine, LCP A2MC, Inst Chim Phys & Mat, 1 Bd Arago, F-57070 Metz, France.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Shallow donor inside core/shell spherical nanodot: Effect of nanostructure size and dielectric environment on energy spectrum2017In: Superlattices and Microstructures, ISSN 0749-6036, E-ISSN 1096-3677, Vol. 111, p. 976-982Article in journal (Refereed)
    Abstract [en]

    We have reported the impact of the core and shell radii on the energy spectrum of centered shallow donor confined inside CdSe/ZnTe core/shell quantum dot and ZnTe/CdSe inverted core/shell quantum dot. The dielectric discontinuity between the nanosystems and their surrounding medium was considered. In order to examine the behavior of the donor binding energy as a function of the spatial parameters a variational approach within the framework of the effective-mass approximation was deployed. Our model shows that for a fixed shell radius the increase of the core radius value blue-shifts the binding energy of the donor inside inverted core/shell quantum dot only if the value of the core to shell radii ratio is between 0.9 and 1, otherwise it is red-shifted. By contrast, for core/shell quantum dot system the binding energy is red-shifted by increasing the core radius for a fixed nanostructure size and for all values of the core to shell radii ratio. We have also found that the donor binding energy values are more important in a core/shell nanodot than in an inverted core/shell quantum dot.

  • 105.
    Chafai, A.
    et al.
    Univ Moulay Ismail, Dept Phys, Fac Sci, LP2MS,Unite Associee CNRST URAC 08, BP 11201, Meknes, Morocco.
    Essaoudi, I.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Univ Moulay Ismail, Dept Phys, Fac Sci, LP2MS,Unite Associee CNRST URAC 08, BP 11201, Meknes, Morocco.
    Ainane, A.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Univ Moulay Ismail, Dept Phys, Fac Sci, LP2MS,Unite Associee CNRST URAC 08, BP 11201, Meknes, Morocco;Univ Lorraine, LCP A2MC, F-57000 Metz, France.
    Dujardin, F.
    Univ Lorraine, LCP A2MC, F-57000 Metz, France.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Recombination energy for negatively charged excitons inside type-II core/shell spherical quantum dots2018In: Physica. E, Low-Dimensional systems and nanostructures, ISSN 1386-9477, E-ISSN 1873-1759, Vol. 101, p. 125-130Article in journal (Refereed)
    Abstract [en]

    The recombination energy of isolated neutral exciton and that of isolated negatively charged exciton inside a type-II core/shell spherical quantum dot are studied. Our investigation considers the charge-carriers effective mass discontinuity at the surface contact between the core and shell materials. Although our model omits the effect of the surface polarization, the dielectric-constant mismatch at the nanodot boundaries was taken into account. In order to achieve the exciton and negative trion energies, we proceed by a variational calculation in the framework of the envelope approximation. Our results reveal a strong correlation between the nanodot morphology and the energy spectrum of the neutral and negatively charged exciton.

  • 106.
    Chafai, A.
    et al.
    Univ Moulay Ismail, Fac Sci, LP2MS, Unite Associee,CNRST URAC 08,Phys Dept, BP 11201, Meknes, Morocco.
    Essaoudi, I.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Univ Moulay Ismail, Fac Sci, LP2MS, Unite Associee,CNRST URAC 08,Phys Dept, BP 11201, Meknes, Morocco.
    Ainane, A.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Univ Moulay Ismail, Fac Sci, LP2MS, Unite Associee,CNRST URAC 08,Phys Dept, BP 11201, Meknes, Morocco;Univ Lorraine, LCP A2MC, Inst Chim Phys & Mat, 1 Bd Arago, F-57070 Metz, France.
    Dujardin, F.
    Univ Lorraine, LCP A2MC, Inst Chim Phys & Mat, 1 Bd Arago, F-57070 Metz, France.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Role of a uniform magnetic field on the energy spectrum of a single donor in a core/shell spherical quantum dot2019In: Zhongguó wùli xuékan, ISSN 0577-9073, Vol. 57, p. 189-194Article in journal (Refereed)
    Abstract [en]

    Using the variational approach within the framework of the effective-mass approximation (EMA), the binding energy of a centred hydrogenic donor impurity in a CdSe/ZnTe core/shell spherical quantum dot (CSSQD) in the presence of an external magnetic field was investigated. In this model, we have taken into account the effect of the radial dependence of the dielectric constant and of the electron effective mass. Our numerical results show a remarkable influence of the nanodot spatial parameters and of the external magnetic field strength on the shallow donor binding energy.

  • 107.
    Chafai, A.
    et al.
    Univ Moulay Ismail, Phys Dept, Unite Associee CNRST URAC 08, Lab Phys Mat & Modelisat Syst,LP2MS,Fac Sci, BP 11201, Meknes, Morocco..
    Essaoudi, I.
    Univ Moulay Ismail, Phys Dept, Unite Associee CNRST URAC 08, Lab Phys Mat & Modelisat Syst,LP2MS,Fac Sci, BP 11201, Meknes, Morocco.;Uppsala Univ, Dept Phys & Astron, Condensed Matter Theory Grp, S-75120 Uppsala, Sweden..
    Ainane, A.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Dujardin, F.
    Univ Lorraine, LCP A2MC, Inst Chim Phys & Mat, 1 Bd Arago, F-57070 Metz, France..
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Tuning the binding energy of on-center donor in CdSe/ZnTe core/shell quantum dot by spatial parameters and magnetic field strength2017In: Physica. E, Low-Dimensional systems and nanostructures, ISSN 1386-9477, E-ISSN 1873-1759, Vol. 94, p. 96-99Article in journal (Refereed)
    Abstract [en]

    The behavior of the electron ground state and of the ground state binding energy of an on-center donor confined in a CdSe/ZnTe core/shell spherical nanodot was examined theoretically within the framework of the effectivemass approximation and using a variational calculation. The radial dependence of the dielectric constant and of the electron effective mass as well as the effect of the polarization charge were considered. Our results highlight the large impact of the magnetic field strength and the spatial parameters on the energy behavior for both the electron and the donor. Our study points out also the fact that the magnetic confinement may be eclipsed by the spatial confinement in heteronanostructures with small size and expected to be dominant in the opposite case.

  • 108.
    Chafai, A.
    et al.
    Univ Moulay Ismail, Fac Sci, Phys Dept, LP2MS,Unite Associee CNRST URAC 08, BP 11201, Meknes, Morocco.
    Essaoudi, I.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. Univ Moulay Ismail, Fac Sci, Phys Dept, LP2MS,Unite Associee CNRST URAC 08, BP 11201, Meknes, Morocco.
    Ainane, Abdelmajid
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Univ Moulay Ismail, Fac Sci, Phys Dept, LP2MS,Unite Associee CNRST URAC 08, BP 11201, Meknes, Morocco;Univ Lorraine, LCP A2MC, Inst Chim Phys & Mat, 1 Bd Arago, F-57070 Metz, France.
    Dujardin, F.
    Univ Lorraine, LCP A2MC, Inst Chim Phys & Mat, 1 Bd Arago, F-57070 Metz, France.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Binding energy of an exciton in a GaN/AlN nanodot: Role of size and external electric field2019In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 559, p. 23-28Article in journal (Refereed)
    Abstract [en]

    We report the impact of an external electric field on the energy spectrum of an exciton inside a spherical shaped GaN/AlN core/shell nanodot. The modulation of the confined exciton lowest state energy by the nanodot size is also treated. Our theoretical approach, based on a variational calculation, predicts a remarkable decrease in the exciton's energy when the electric field is switched on. Furthermore, our investigation shows that for a fixed nanodot size, the energy redshift is a unique function of the external electric field strength. On the other hand, it was observed that as the nanodot size increases the lowest exciton energy decreases and vice versa.

  • 109.
    Chafai, A.
    et al.
    Univ Moulay Ismail, Fac Sci, Phys Dept, Unite Associee CNRST URAC 08,LP2MS, BP 11201, Meknes, Morocco.
    Essaoudi, I
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Univ Moulay Ismail, Fac Sci, Phys Dept, Unite Associee CNRST URAC 08,LP2MS, BP 11201, Meknes, Morocco.
    Ainane, Abdelmajid
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Univ Moulay Ismail, Fac Sci, Phys Dept, Unite Associee CNRST URAC 08,LP2MS, BP 11201, Meknes, Morocco;Univ Lorraine, LCP A2MC, F-57000 Metz, France.
    Dujardin, F.
    Univ Lorraine, LCP A2MC, F-57000 Metz, France.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Hydrogenic donor in a CdSe/CdS quantum dot: Effect of electric field strength, nanodot shape and dielectric environment on the energy spectrum2018In: Physica. E, Low-Dimensional systems and nanostructures, ISSN 1386-9477, E-ISSN 1873-1759, Vol. 104, p. 29-35Article in journal (Refereed)
    Abstract [en]

    The impact of an external electric field on the binding energy of a single donor impurity was examined within the effective-mass approach by deploying a variational calculation. The discontinuity of the permittivity, epsilon(r), and of the particle effective mass, m(i)*(r), at the nanosystem boundaries was considered. Using the image charge approach, the impact of the surrounding medium on the shallow donor energy spectrum was also taken into account. Our theoretical investigation shows that, for zero electric field and when the shell thickness is taken constant, the increase of the core material size leads to decrease the single donor correlation energy. Further, for a fixed core material size the energy decreases quickly when the shell thickness moves from 0 to 1 nm, while it decreases very slowly when the shell thickness is ranged between 1 nm and 4 nm. On the other hand, we have established that when we turn on an external electric field, the probability density of confined particles tends to move towards the nanodot border which naturally shifts the energy spectrum to lower energies (redshift). It was also obtained that the donor Stark shift depends not only on the nanodot size, but also on the surrounding medium.

  • 110.
    Chakraborty, Sudip
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Banerjee, Amitava
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Watcharatharapong, Teeraphat
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Araujo, Rafael Barros
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Royal Inst Technol KTH, Dept Mat & Engn, Appl Mat Phys, Stockholm, Sweden.
    Current computational trends in polyanionic cathode materials for Li and Na batteries2018In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 30, no 28, article id 283003Article, review/survey (Refereed)
    Abstract [en]

    A long-standing effort has been devoted for the development of high energy density cathodes both for Li-and Na-ion batteries (LIBs and SIBs). The scientific communities in battery research primarily divide the Li- and Na-ion cathode materials into two categories: layered oxides and polyanionic compounds. Researchers are trying to improve the energy density of such materials through materials screening by mixing the transition metals or changing the concentration of Li or Na in the polyanionic compounds. Due to the fact that there is more stability in the polyanionic frameworks, batteries based on these materials mostly provide a prolonged cycling life as compared to the layered oxide materials. Nevertheless, the bottleneck for such compounds is the weight penalty from polyanionic groups that results into the lower capacity. The anion engineering could be considered as an essential way out to design such polyanionic compounds to resolve this issue and to fetch improved cathode performance. In this topical review we present a systematic overview of the polyanionic cathode materials used for LIBs and SIBs. We will also present the computational methodologies that have become significantly relevant for battery research. We will make an attempt to provide the theoretical insight with a current development in sulfate (SO4), silicate (SiO4) and phosphate (PO4) based cathode materials for LIBs and SIBs. We will end this topical review with the future outlook, that will consist of the next generation organic electrode materials, mainly based on conjugated carbonyl compounds.

  • 111.
    Chakraborty, Sudip
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Xie, Wei
    Univ Calif Berkeley, Dept Mat Sci & Engn, Berkeley, CA 94720 USA..
    Mathews, Niripan
    Nanyang Technol Univ, Sch Mat Sci & Engn, Nanyang Ave, Singapore 639798, Singapore.;ERI N, Res Techno Plaza,X Frontier Block,Level 5, Singapore 637553, Singapore..
    Sherburne, Matthew
    Univ Calif Berkeley, Dept Mat Sci & Engn, Berkeley, CA 94720 USA..
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Asta, Mark
    Univ Calif Berkeley, Dept Mat Sci & Engn, Berkeley, CA 94720 USA..
    Mhaisalkar, Subodh G.
    Nanyang Technol Univ, Sch Mat Sci & Engn, Nanyang Ave, Singapore 639798, Singapore.;ERI N, Res Techno Plaza,X Frontier Block,Level 5, Singapore 637553, Singapore..
    Rational Design: A High-Throughput Computational Screening and Experimental Validation Methodology for Lead-Free and Emergent Hybrid Perovskites2017In: ACS ENERGY LETTERS, ISSN 2380-8195, Vol. 2, no 4, p. 837-845Article in journal (Refereed)
    Abstract [en]

    Perovskite solar cells, with efficiencies of 22.1%, are the only solution-processable technology to outperform multicrystalline silicon and thin-film solar cells. Whereas substantial progress has been made in scalability and stability, toxicity concerns drive the need for lead replacement, intensifying research into the broad palette of elemental substitutions, solid solutions, and multidimensional structures. Perovskites have gone from comprising three to more than eight (CH3NH3, HC(NH2)(2), Cs, Rb, Pb, Sn, I, Br) organic and inorganic constituents, and a variety of new embodiments including layered, double perovskites, and metal-deficient perovskites are being explored. Although most experimentation is guided by intuition and trial-and-error-based Edisonian approaches, rational strategies underpinned by computational screening and targeted experimental validation are emerging. In addressing emergent perovskites, this perspective discusses the rational design methodology leveraging density functional theory-based high-throughput computational screening coupled to downselection strategies to accelerate the discovery of materials and industrialization of perovskite solar cells.

  • 112.
    Cheng, Kai
    et al.
    Dalian Univ Technol, Minist Educ, Key Lab Mat Modificat Laser Ion & Electron Beams, Dalian 116024, Peoples R China.
    Guo, Yu
    Dalian Univ Technol, Minist Educ, Key Lab Mat Modificat Laser Ion & Electron Beams, Dalian 116024, Peoples R China.
    Han, Nannan
    Dalian Univ Technol, Minist Educ, Key Lab Mat Modificat Laser Ion & Electron Beams, Dalian 116024, Peoples R China.
    Jiang, Xue
    Dalian Univ Technol, Minist Educ, Key Lab Mat Modificat Laser Ion & Electron Beams, Dalian 116024, Peoples R China.
    Zhang, Junfeng
    Shanxi Normal Univ, Sch Phys & Informat Engn, Linfen 041000, Peoples R China.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Su, Yan
    Dalian Univ Technol, Minist Educ, Key Lab Mat Modificat Laser Ion & Electron Beams, Dalian 116024, Peoples R China.
    Zhao, Jijun
    Dalian Univ Technol, Minist Educ, Key Lab Mat Modificat Laser Ion & Electron Beams, Dalian 116024, Peoples R China.
    2D lateral heterostructures of group-III monochalcogenide: Potential photovoltaic applications2018In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 112, no 14, article id 143902Article in journal (Refereed)
    Abstract [en]

    Solar photovoltaics provides a practical and sustainable solution to the increasing global energy demand. Using first-principles calculations, we investigate the energetics and electronic properties of two-dimensional lateral heterostructures by group-III monochalcogenides and explore their potential applications in photovoltaics. The band structures and formation energies from supercell calculations demonstrate that these heterostructures retain semiconducting behavior and might be synthesized in laboratory using the chemical vapor deposition technique. According to the computed band offsets, most of the heterojunctions belong to type II band alignment, which can prevent the recombination of electron-hole pairs. Besides, the electronic properties of these lateral heterostructures can be effectively tailored by the number of layers, leading to a high theoretical power conversion efficiency over 20%.

  • 113.
    Choudhuri, Indrani
    et al.
    Indian Inst Technol, Sch Basic Sci, Discipline Chem, Indore 452020, Madhya Pradesh, India..
    Patra, Nandini
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. Indian Inst Technol, Ctr Mat Sci & Engn, Indore 452020, Madhya Pradesh, India..
    Mahata, Arup
    Indian Inst Technol, Sch Basic Sci, Discipline Chem, Indore 452020, Madhya Pradesh, India..
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Royal Inst Technol KTH, Dept Mat Sci & Engn, Appl Mat Phys, S-10044 Stockholm, Sweden..
    Pathak, Biswarup
    Indian Inst Technol, Sch Basic Sci, Discipline Chem, Indore 452020, Madhya Pradesh, India.;Indian Inst Technol, Ctr Mat Sci & Engn, Indore 452020, Madhya Pradesh, India..
    B-N@Graphene: Highly Sensitive and Selective Gas Sensor2015In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 119, no 44, p. 24827-24836Article in journal (Refereed)
    Abstract [en]

    We have performed density functional theory (DFT) calculations to study the gas (CO, CO2, NO, and NO2) sensing mechanism of pure and doped (B@, N@, and B-N@) graphene surfaces. The calculated adsorption energies of the various toxic gases (CO, CO2, NO, and NO2) on the pure and doped graphene surfaces show, doping improves adsorption energy and selectivity. The electronic properties of the B-N@graphene surfaces change significantly compared to pure and B@ and N@graphene surfaces, while selective gas molecules are adsorbed. So, we report B-N codoping on graphene can be highly sensitive and selective for semiconductor-based gas sensor.

  • 114.
    Colarieti-Tosti, M.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Simak, S. I.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Nordström, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Åberg, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Condensed Matter Theory.
    Edvardsson, S.
    Brooks, Michael S. S.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Origin of Magnetic Anisotropy of Gd Metal2003In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 91, no 15, p. 157201-157204Article in journal (Refereed)
    Abstract [en]

    Using first-principles theory, we have calculated the energy of Gd as a function of spin direction, θ, between the c and a axes and found good agreement with experiment for both the total magnetic anisotropy energy and its angular dependence. The calculated low temperature direction of the magnetic moment lies at an angle of 20° to the c axis. The calculated magnetic anisotropy energy of Gd metal is due to a unique mechanism involving a contribution of 7.5  μeV from the classical dipole-dipole interaction between spins plus a contribution of 16  μeV due to the spin-orbit interaction of the conduction electrons. The 4f spin polarizes the conduction electrons via exchange interaction, which transfers the magnetic anisotropy of the conduction electrons to the 4f spin.

  • 115.
    Colarieti-Tosti, Massimiliano
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics IV. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Theoretical Magnetism.
    Simak, Sergei
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics IV. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Theoretical Magnetism.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics IV. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Theoretical Magnetism.
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics IV. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Theoretical Magnetism.
    Nordström, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics IV. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Theoretical Magnetism.
    Edwardsson, Sverker
    Brooks, Michael
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics IV. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Theoretical Magnetism.
    On the magnetic anisotropy of Gd metal2003In: Physical Review Letters, Vol. 91, p. 157201-Article in journal (Refereed)
  • 116.
    Cricchio, F
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics.
    Ahuja, Rajeev
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics.
    High Pressure melting of Lead2006In: Phys. Rev. B, Vol. 73, p. 140103-Article in journal (Refereed)
  • 117.
    Dahlstrand, Christian
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Jahn, Burkhard O.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Grigoriev, Anton
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Villaume, Sebastien
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ottosson, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Polyfulvenes: Polymers with "Handles" That Enable Extensive Electronic Structure Tuning2015In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 119, no 46, p. 25726-25737Article in journal (Refereed)
    Abstract [en]

    The fundamental electronic structure properties of substituted poly(penta)fulvenes and pentafulvene-based polymers are analyzed through qualitative molecular orbital (MO) theory combined with calculations at the B3LYP and HSE06 hybrid density functional theory (DFT) levels. We argue that the pentafulvene monomer unit has a unique character because electron density in the exocyclic C=C double bond can be polarized into and out of the five-membered ring, a feature that is not available to other more commonly used monomers. It is investigated how the energy gaps between the highest occupied and lowest unoccupied molecular orbitals (HOMO and LUMO, respectively), as approximate band gaps, are influenced by exocyclic substitution, introduction of linker groups, benzannulation, and ring substitution. In particular, the exocyclic positions of the fulvene act as handles by which the electronic structure of the polymer can be tuned between the quinoid and fulvenoid valence bond isomers; electron-withdrawing exocyclic substituents lead to polyfulvenes in the quinoid form while those with electron-donating substituents prefer the fulvenoid. Taken together, the HOMO-LUMO gaps of polyfulvenes can be tuned extensively, varying in ranges 0.77-2.44 eV (B3LYP) and 0.35-2.00 eV (HSE06) suggesting that they are a class of polymers with highly interesting, yet nearly unexplored, properties.

  • 118. Dallera, C.
    et al.
    Wessely, Ola
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Colarieti-Tosti, M.
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Johansson, Börje
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Katsnelson, M. I.
    Annese, E.
    Rueff, J.-P.
    Vank'o, G.
    Braicovich, L.
    Grioni, M.
    Understanding mixed valent materials: Effects of dynamical core-hole screening in high-pressure x-ray spectroscopy2006In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 74, no 8, p. 081101-Article in journal (Refereed)
    Abstract [en]

    Changes in the electronic structure of Yb, a material whose valence is modified under pressure, are observed with remarkable detail in x-ray absorption and emission data measured between ambient conditions and 20 GPa. These changes are reproduced by a theory that essentially does not rely on experimental parameters, and includes dynamical core-hole screening. From the combined experimental and theoretical data we can firmly establish on a quantitative level how the valency of an intermediate valence material is modified by pressure. In metallic Yb it increases from 2 to 2.55 +/- 0.05 between 0 and 20 GPa.

  • 119.
    Das, Suman
    et al.
    Indian Inst Sci, Solid State & Struct Chem Unit, Bengaluru 560012, India..
    Swain, Diptikanta
    Indian Inst Sci, Solid State & Struct Chem Unit, Bengaluru 560012, India..
    Araujo, Rafael Barros Neves de
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Shi, Songxin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Beihang Univ, Sch Mat Sci & Engn, Beijing 100191, Peoples R China..
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Royal Inst Technol KTH, Dept Mat & Engn, Appl Mat Phys, S-10044 Stockholm, Sweden..
    Row, Tayur N. Guru
    Indian Inst Sci, Solid State & Struct Chem Unit, Bengaluru 560012, India..
    Bhattacharyya, Aninda J.
    Indian Inst Sci, Solid State & Struct Chem Unit, Bengaluru 560012, India..
    Alloying in an Intercalation Host: Metal Titanium Niobates as Anodes for Rechargeable Alkali-Ion Batteries2018In: Chemistry - An Asian Journal, ISSN 1861-4728, E-ISSN 1861-471X, Vol. 13, no 3, p. 299-310Article in journal (Refereed)
    Abstract [en]

    We discuss here a unique flexible non-carbonaceous layered host, namely, metal titanium niobates (M-Ti-niobate, M: Al3+, Pb2+, Sb3+, Ba2+, Mg2+), which can synergistically store both lithium ions and sodium ions via a simultaneous intercalation and alloying mechanisms. M-Ti-niobate is formed by ion exchange of the K+ ions, which are specifically located inside galleries between the layers formed by edge and corner sharing TiO6 and NbO6 octahedral units in the sol-gel synthesized potassium titanium niobate (KTiNbO5). Drastic volume changes (approximately 300-400%) typically associated with an alloying mechanism of storage are completely tackled chemically by the unique chemical composition and structure of the M-Ti-niobates. The free space between the adjustable Ti/Nb octahedral layers easily accommodates the volume changes. Due to the presence of an optimum amount of multivalent alloying metal ions (50-75% of total K+) in the M-Ti-niobate, an efficient alloying reaction takes place directly with ions and completely eliminates any form of mechanical degradation of the electroactive particles. The M-Ti-niobate can be cycled over a wide voltage range (as low as 0.01V) and displays remarkably stable Li+ and Na+ ion cyclability (>2 Li+/Na+ per formula unit) for widely varying current densities over few hundreds to thousands of successive cycles. The simultaneous intercalation and alloying storage mechanisms is also studied within the density functional theory (DFT) framework. DFT expectedly shows a very small variation in the volume of Al-titanium niobate following lithium alloying. Moreover, the theoretical investigations also conclusively support the occurrence of the alloying process of Li ions with the Al ions along with the intercalation process during discharge. The M-Ti-niobates studied here demonstrate a paradigm shift in chemical design of electrodes and will pave the way for the development of a multitude of improved electrodes for different battery chemistries.

  • 120.
    Das, Tisita
    et al.
    Indian Assoc Cultivat Sci, Dept Mat Sci, India.
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Royal Inst Technol KTH, Dept Mat & Engn, Appl Mat Phys, Stockholm, Sweden.
    Das, Gour P.
    Indian Assoc Cultivat Sci, Dept Mat Sci, Kolkata, India.
    TiS2 Monolayer as an Emerging Ultrathin Bifunctional Catalyst: Influence of Defects and Functionalization2019In: ChemPhysChem, ISSN 1439-4235, E-ISSN 1439-7641, Vol. 20, no 4, p. 608-617Article in journal (Refereed)
    Abstract [en]

    We have envisaged the hydrogen evolution and oxygen evolution reactions (HER and OER) on a two‐dimensional (2D) noble‐metal‐free titanium disulfide (TiS2) monolayer, which belongs to the exciting family of transition metal dichalcogenides (TMDCs). Our theoretical investigation to probe the HER and OER on both the H and T phases of 2D TiS2 is based on electronic‐structure calculations witihin the framework of density functional theory (DFT). Since TiS2 is the lightest compound among the group‐IV TMDCs, it is worth exploring the catalytic activity of a TiS2 monolayer through the functionalization at the anion (S) site, substituting with P, N, and C dopants as well as by incorporating single sulfur vacancy defects. We have investigated the effect of functionalization and vacancy defects on the structural, electronic, and optical response of a TiS2 monolayer by determining the density of states, work‐function, and optical absorption spectra. We have determined the HER and OER activities for the functionalized and defective TiS2 monolayers based on the reaction coordinate, which can be constructed from the adsorption free energies of the intermediates (H*, O*, OH* and OOH*, where * denotes the adosrbed state) in the HER and OER mechanisms. Finally, we have shown that TiS2 monolayers are emerging as a promising material for the HER and OER mechanisms under the influence of functionalization and defects.

  • 121.
    de Almeida, J. S.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science.
    Kim, D. Y.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science.
    Ortiz, C.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science.
    Klintenberg, Mattias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science.
    On the dynamical stability and metallic behavior of YH3 under pressure2009In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 94, no 25, p. 251913-Article in journal (Refereed)
    Abstract [en]

    Wereport on the behavior of structural and electronic properties ofyttrium trihydride under pressure using first principles calculations. We showthat YH3 undergoes a structural transformation and its high pressurephase is dynamically stable under pressure since the peak atthe imaginary frequencies of the phonon density of states, whichaccount for the structural instability disappears at high pressure. Additionally,our GW calculations indicate a metallization of the high pressurecubic phase of YH3.

  • 122. De Sarkar, Abir
    et al.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Electronic charge transport through ZnO nanoribbons2014In: Journal of Physics and Chemistry of Solids, ISSN 0022-3697, E-ISSN 1879-2553, Vol. 75, no 11, p. 1223-1228Article in journal (Refereed)
    Abstract [en]

    I-V characteristics of ZnO nanoribbons (NRs) have been investigated using density functional theory coupled to non-equilibrium Green's Function. The current through the NRs drops with the increasing NR width, leveling off to 1.66 and 0.42 mu A in zig-zag and arm-chair NRs respectively for widths similar to 20 angstrom at 3 V of electrical bias. The transconductance as well as the current flowing through the arm-chair NRs decays exponentially with NR width for both odd and even number of dimer lines traversed. The current through the zig-zag NRs falls off exponentially with NR width, being insensitive to the odd or even numbers of zig-zag lines appearing along the normal to the charge transport direction.

  • 123. Dera, Przemyslaw
    et al.
    Nisar, Jawad
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Tkachev, Sergey
    Prakapenka, Vitali B.
    New type of possible high-pressure polymorphism in NiAs minerals in planetary cores2013In: Physics and chemistry of minerals, ISSN 0342-1791, E-ISSN 1432-2021, Vol. 40, no 2, p. 183-193Article in journal (Refereed)
    Abstract [en]

    The nickel arsenide (B8(1)) and related crystal structures are among the most important crystallographic arrangements assumed by Fe and Ni compounds with light elements such as Si, O, S, and P, expected to be present in planetary cores. Despite the simple structure, some of these materials like troilite (FeS) exhibit complex phase diagrams and rich polymorphism, involving significant changes in interatomic bonding and physical properties. NiP (oP16) represents one of the two principal structure distortions found in the nickel arsenide family and is characterized by P-P bonding interactions that lead to the formation of P-2 dimers. In the current study, the single-crystal synchrotron X-ray diffraction technique, aided by first principles density functional theory (DFT) calculations, has been applied to examine the compression behavior of NiP up to 30 GPa. Two new reversible displacive phase transitions leading to orthorhombic high-pressure phases with Pearson symbols oP40 and oC24 were found to occur at approximately 8.5 and 25.0 GPa, respectively. The oP40 phase has the primitive Pnma space group with unit cell a = 4.7729(5) , b = 16.6619(12) , and c = 5.8071(8) at 16.3(1) GPa and is a superstructure of the ambient oP16 phase with multiplicity of 2.5. The oC24 phase has the acentric Cmc2(1) space group with unit cell a = 9.695(6) , b = 5.7101(9) , and c = 4.7438(6) at 28.5(1) GPa and is a superstructure of the oP16 phase with multiplicity of 1.5. DFT calculations fully support the observed sequence of phase transitions. The two new phases constitute logical next stages of P sublattice polymerization, in which the dilution of the P-3 units, introduced in the first high-pressure phase, decreases, leading to compositions of Ni-20(P-3)(4)(P-2)(4) and Ni-12(P-3)(4), and provide important clues to understanding of phase relations and transformation pathways in the NiAs family.

  • 124. Deshpande, M D
    et al.
    Scheicher, Ralph H
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics IV.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics IV.
    Pandey, Ravindra
    Binding strength of sodium ions in cellulose for different water contents2008In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 112, no 30, p. 8985-8989Article in journal (Refereed)
    Abstract [en]

    The interaction strength of sodium ions (Na(+)) with cellulose is investigated from first principles for varying degrees of water content. We find that the interaction of water molecules and Na(+) can be studied independently at the various OH groups in cellulose which we categorize as two different types. In the absence of water, Na(+) forms strong ionic bonds with the OH groups of cellulose. When water molecules are anchored to the OH groups via hydrogen bonds, Na(+) can eventually no longer bind to the OH groups, but will instead interact with the oxygen atoms of the water molecules. Due to the rather weak attachment of the latter to the OH groups, Na(+) becomes effectively more mobile in the fully hydrated cellulose framework. The present study thus represents a significant step toward a first-principles understanding of the experimentally observed dependence of ionic conductivity on the level of hydration in cellulose network.

  • 125.
    Ding, Feng
    et al.
    Fysiska Institutionen, Göteborgs Universitet.
    Larsson, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Materials Theory.
    Larsson, J Andreas
    Tyndall National Institute, Unversity College Cork.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Materials Theory.
    Duan, Haiming
    Fysiska Institutionen, Göteborgs Universitet.
    Rosén, Arne
    Fysiska Institutionen, Göteborgs Universitet.
    Bolton, Kim
    University College of Borås.
    The importance of strong carbon-metal adhesion for catalytic nucleation of single-walled carbon nanotubes2008In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 8, no 2, p. 463-468Article in journal (Refereed)
    Abstract [en]

    Density functional theory is used to show that the adhesion between single-walled carbon nanotubes (SWNTs) and the catalyst particles from which they grow needs to be strong to support nanotube growth. It is found that Fe, Co, and Ni, commonly used to catalyze SWNT growth, have larger adhesion strengths to SWNTs than Cu, Pd, and Au and are therefore likely to be more efficient for supporting growth. The calculations also show that to maintain an open end of the SWNT it is necessary that the SWNT adhesion strength to the metal particle is comparable to the cap formation energy of the SWNT end. This implies that the difference between continued and discontinued SWNT growth to a large extent depends on the carbon-metal binding strength, which we demonstrate by molecular dynamics (MD) simulations. The results highlight that first principles computations are vital for the understanding of the binding strength's role in the SWNT growth mechanism and are needed to get accurate force field parameters for MD.

  • 126. Ding, Yang
    et al.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Shu, Jinfu
    Chow, Paul
    Luo, Wei
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Mao, Ho-kwang
    Structural phase transition of vanadium at 69 GPa2007In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 98, no 8, p. 085502-Article in journal (Refereed)
    Abstract [en]

    A phase transition was observed at 63-69 GPa and room temperature in vanadium with synchrotron x-ray diffraction. The transition is characterized as a rhombohedral lattice distortion of the body-centered-cubic vanadium without a discontinuity in the pressure-volume data, thus representing a novel type of transition that has never been observed in elements. Instead of driven by the conventional s-d electronic transition mechanism, the phase transition could be associated with the softening of C-44 trigonal elasticity tensor that originates from the combination of Fermi surface nesting, band Jahn-Teller distortion, and electronic topological transition.

  • 127. Dixit, M.
    et al.
    Maark, Tuhina Adit
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ghatak, K.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Pal, S.
    Scandium-decorated MOF-5 as potential candidates for room-temperature hydrogen storage: A solution for the clustering problem in MOFs2012In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 116, no 33, p. 17336-17342Article in journal (Refereed)
    Abstract [en]

    Transition-metal-based systems show promising binding energy for hydrogen storage but suffer from clustering problem. The effect of light transition metal (M = Sc, Ti) decoration, boron substitution on the hydrogen storage properties of MOF-5, and clustering problem of metals has been investigated using ab initio density functional theory. Our results of solid-tate calculations reveal that whereas Ti clusters strongly Sc atoms do not suffer from this problem when decorating MOF-5. Boron substitution on metal-decorated MOF-5 enhances the interaction energy of both the metals with MOF-5. Sc-decorated MOF-5 shows a hydrogen storage capacity of 5.81 wt % with calculated binding energies of 20-40 kJ/mol, which ensures the room-temperature applicability of this hydrogen storage material.

  • 128.
    Djouambi, Nadia
    et al.
    Univ Badji Mokhtar Annaba, Lab Mat Avances, BP 12, El Hadjar 23000, Annaba, Algeria.
    Bougheloum, Chafika
    Univ Badji Mokhtar Annaba, Lab Mat Avances, BP 12, El Hadjar 23000, Annaba, Algeria.
    Messalhi, Abdelrani
    Univ Badji Mokhtar Annaba, Lab Mat Avances, BP 12, El Hadjar 23000, Annaba, Algeria.
    Bououdina, Mohamed
    Univ Bahrain, Coll Sci, Dept Phys, POB 32038, Zallaq, Bahrain.
    Banerjee, Amitava
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Royal Inst Technol KTH, Dept Mat & Engn, Appl Mat Phys, S-10044 Stockholm, Sweden.
    New Concept on Photocatalytic Degradation of Thiophene Derivatives: Experimental and DFT Studies2018In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 122, no 27, p. 15646-15651Article in journal (Refereed)
    Abstract [en]

    In this study, the photocatalytic degradation of seven sulfur compounds (2-methylthiophene, 3-methylthiophene, 2-phenylthiophene, 3-phenylthiophene, 2,5-diphenylthiophene, 2-(2-thienyl) pyridine, and 2-(3-thienyl) pyridine in semiaqueous medium are compared to thiophene. The apparent-reaction-rate constant (k) is found to decrease in the following order: 2,5-diphenylthiophene > 2-(2-thienyl) pyridine > 2-penhylthiophene methylthiophene > 3-penhylthiophene > 2-methylthiophene > 2-(3-thienyl) pyridine > 3-thiophene. From the data obtained by UV light absorption (lambda(max)) measurements and electronic structure calculations (frontier orbitals energy, global hardness, and global softness), the kinetic parameters of the reaction have been determined. Among the studied compounds, thiophene with a high lambda(max) and low calculated LUMO-HOMO gap energy has showed higher activity under UV irradiation. Interestingly, a lower activity is observed with low lambda(max) and high LUMO-HOMO gap energy. This demonstrates, for the first time, that the reactivity depends essentially on the thermodynamic stability of the sulfur compound rather than on the nature or the position of the substituent on the ring.

  • 129. Dubrovinskaia, N.
    et al.
    Dubrovinsky, L.
    Kantor, I.
    Crichton, W. A.
    Dmitriev, V.
    Prakapenka, V.
    Shen, G.
    Vitos, Levente
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics IV.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics IV.
    Johansson, Börje
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics IV.
    Abrikosov, I. A.
    Beating the miscibility barrier between iron and magnesium by high-pressure alloying2005In: Physical Review Letters, Vol. 95, p. 245502-Article in journal (Refereed)
  • 130. Dubrovinsky, L.
    et al.
    Dubrovinskaia, N.
    Crichton, W. A.
    Mikhaylushkin, Arkady S.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Simak, S. I.
    Abrikosov, I. A.
    de Almeida, J. Souza
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Ahuja, Rajeev B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Luo, Wei
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Johansson, B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Noblest of all metals is structurally unstable at high pressure2007In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 98, no 4, p. 045503-Article in journal (Refereed)
    Abstract [en]

    In a series of experiments in externally electrically heated diamond anvil cells we demonstrate that at pressures above similar to 240 GPa gold adopts a hexagonal-close-packed structure. Ab initio calculations predict that at pressures about 250 GPa different stacking sequences of close-packed atomic layers in gold become virtually degenerate in energy, strongly supporting the experimental observations.

  • 131.
    Dubrovinsky, L.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Dubrovinskaia, N.
    S. de Almeida, J.
    Luo, Wei
    Crichton, W. A.
    Johansson, Börje
    Ahuja, Rajeev
    Relativistic Effects Driven Structural Phase Transition in Gold at High PressureIn: NatureArticle in journal (Refereed)
  • 132.
    Dubrovinsky, LS
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences.
    Saxena, SK
    Lazor, P
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences.
    Ahuja, R
    Eriksson, O
    Wills, JM
    Johansson, B
    Physics, Department of Physics.
    Experimental and theoretical identification of a new high-pressure phase of silica1997In: NATURE, ISSN 0028-0836, Vol. 388, no 6640, p. 362-365Article in journal (Refereed)
    Abstract [en]

    Following the discovery of stishovite (the highest-pressure polymorph of silica known from natural samples), many attempts have been made to investigate the possible existence of denser phases of silica at higher pressures. Based on the crystal structures

  • 133. Dwibedi, Debasmita
    et al.
    Araujo, Rafael B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Shanbogh, Pradeep P.
    Sundaram, Nalini G.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Barpanda, Prabeer
    Na2.44Mn1.79(SO4)(3): a new member of the alluaudite family of insertion compounds for sodium ion batteries2015In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 3, no 36, p. 18564-18571Article in journal (Refereed)
    Abstract [en]

    Sodium-ion batteries have been extensively pursued as economic alternatives to lithium-ion batteries. Investigating the polyanion chemistry, alluaudite structured Na2Fe2II(SO4)(3) has been recently discovered as a 3.8 V positive electrode material (Barpanda et al., Nature Commun., 5: 4358, 2014). Registering the highest ever Fe-III/Fe-II redox potential (vs. Na/Na+) and formidable energy density, it has opened up a new polyanion family for sodium batteries. Exploring the alluaudite family, here we report isotypical Na2+2xMn2-xII(SO4)(3) (x = 0.22) as a novel high-voltage cathode material for the first time. Following low-temperature (ca. 350 degrees C) solid-state synthesis, the structure of this new alluaudite compound has been solved adopting a monoclinic framework (s.g. C2/c) showing antiferromagnetic ordering at 3.4 K. Synergising experimental and ab initio DFT investigation, Na2+2xMn2-xII(SO4)(3) has been found to be a potential high-voltage (ca. 4.4 V) cathode material for sodium batteries.

  • 134.
    Dwibedi, Debasmita
    et al.
    Indian Inst Sci, Mat Res Ctr, Faraday Mat Lab, CV Raman Ave, Bangalore 560012, Karnataka, India..
    Gond, Ritambhara
    Indian Inst Sci, Mat Res Ctr, Faraday Mat Lab, CV Raman Ave, Bangalore 560012, Karnataka, India..
    Dayamani, Allumolu
    Indian Inst Sci, Mat Res Ctr, Faraday Mat Lab, CV Raman Ave, Bangalore 560012, Karnataka, India..
    Araujo, Rafael B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Barpanda, Prabeer
    Indian Inst Sci, Mat Res Ctr, Faraday Mat Lab, CV Raman Ave, Bangalore 560012, Karnataka, India..
    Na2.32Co1.84(SO4)(3) as a new member of the alluaudite family of high-voltage sodium battery cathodes2017In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 46, no 1, p. 55-63Article in journal (Refereed)
    Abstract [en]

    Electrochemical energy storage has recently seen tremendous emphasis being placed on the large-scale (power) grid storage. Sodium-ion batteries are capable of achieving this goal with economic viability. In a recent breakthrough in sodium-ion battery research, the alluaudite framework (Na2Fe2(SO4)(3)) has been reported, with the highest Fe3+/Fe2+ redox potential (ca. 3.8 V, Barpanda, et al., Nat. Commun., 2014, 5, 4358). Exploring this high-voltage sodium insertion system, we report the discovery of Na2+2xCo2-x(SO4)(3) (x = 0.16) as a new member of the alluaudite class of cathode. Stabilized by low-temperature solid-state synthesis (T <= 350 degrees C),this novel Co-based compound assumes a monoclinic structure with C2/c symmetry, which undergoes antiferromagnetic ordering below 10.2 K. Isotypical to the Fe-homologue, it forms a complete family of solid-solution Na2+2x(Fe1-yCoy)(2-x)(SO4)(3) [ y = 0-1]. Ab initio DFT analysis hints at potential high voltage operation at 4.76-5.76 V (vs. Na), depending on the degree of desodiation involving a strong participation of the oxygen sub-lattice. With the development of safe organic electrolytes, Na2+2xCo2-x(SO4)(3) can work as a cathode material (similar to 5 V) for sodium-ion batteries.

  • 135.
    Dwibedi, Debasmita
    et al.
    Indian Inst Sci, Mat Res Ctr, Faraday Mat Lab, CV Raman Ave, Bangalore 560012, Karnataka, India..
    Ling, Chris D.
    Univ Sydney, Sch Chem, Bldg F11, Sydney, NSW 2006, Australia..
    Araujo, Rafael B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Chakraborty, Sudip
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Duraisamy, Shanmughasundaram
    Indian Inst Sci, Inorgan & Phys Chem, CV Raman Ave, Bangalore 560012, Karnataka, India..
    Munichandraiah, Nookala
    Indian Inst Sci, Inorgan & Phys Chem, CV Raman Ave, Bangalore 560012, Karnataka, India..
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Barpanda, Prabeer
    Indian Inst Sci, Mat Res Ctr, Faraday Mat Lab, CV Raman Ave, Bangalore 560012, Karnataka, India..
    Ionothermal Synthesis of High-Voltage Alluaudite Na2+2xFe2-x(SO4)(3) Sodium Insertion Compound: Structural, Electronic, and Magnetic Insights2016In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 8, no 11, p. 6982-6991Article in journal (Refereed)
    Abstract [en]

    Exploring future cathode materials for sodium-ion batteries, alluaudite class of Na2Fe2II(SO4)(3) has been recently unveiled as a 3.8 V positive insertion candidate (Barpanda et al. Nat. Commun. 2014, 5, 4358). It forms an Fe-based polyanionic compound delivering the highest Fe-redox potential along with excellent rate kinetics and reversibility. However, like all known SO4-based insertion materials, its synthesis is cumbersome that warrants careful processing avoiding any aqueous exposure. Here, an alternate low temperature ionothermal synthesis has been described to produce the alluaudite Na2+2xFe2-xII(SO4)(3). It marks the first demonstration of solvothermal synthesis of alluaudite Na2+2xM2-xII(SO4)(3) (M = 3d metals) family of cathodes. Unlike classical solid-state route, this solvothermal route favors sustainable synthesis of homogeneous nanostructured alluaudite products at only 300 degrees C, the lowest temperature value until date. The current work reports the synthetic aspects of pristine and modified ionothermal synthesis of Na2+2xFe2-xII(SO4)(3) having tunable size (300 nm similar to 5 mu m) and morphology. It shows antiferromagnetic ordering below 12 K. A reversible capacity in excess of 80 mAh/g was obtained with good rate kinetics and cycling stability over 50 cycles. Using a synergistic approach combining experimental and ab initio DFT analysis, the structural, magnetic, electronic, and electrochemical properties and the structural limitation to extract full capacity have been described.

  • 136.
    Edin, Emil
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Luo, Wei
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Kaplan, Bartek
    Sandvik Coromant R&D, Stockholm, Sweden.
    Blomqvist, Andreas
    Sandvik Coromant R&D, Stockholm, Sweden.
    First principles study of C diffusion in WC/W interfaces observed in WC/Co tools after Ti-alloy machining2019In: Computational materials science, ISSN 0927-0256, E-ISSN 1879-0801, Vol. 161, p. 236-243Article in journal (Refereed)
    Abstract [en]

    Ti-alloys have many qualities making them ideal for use in aerospace applications, medical implants and chemical industries such as high strength to weight ratio, good high temperature strength and chemical stability. One downside to Ti-alloys is, however, that they are considered difficult to machine. Several investigations have been made in order to understand the wear mechanisms present in machining of Ti-alloys and the most common understanding is a combination of attrition and dissolution-diffusion. Observations by Odelros et al. [1] have shown that there exists a small layer of pure bcc W on top of the outermost WC grains after turning of Ti-6Al-4V. In order for such a layer to form C has to diffuse away from the WC leaving behind only W. In this work Density Functional Theory (DFT) is used together with Harmonic Transition State Theory (HTST) to investigate the prefactors and barriers for C diffusion into and within two different WC/W interfaces, [0001]/[111] and [10 (1) over bar0]/[100]. The diffusion into the interfaces show that the barrier for the [0001]/[111] interface is more than twice as high as the barrier for the [10 (1) over bar0]/[100] interface. Diffusion within the interfaces show, on average, slightly higher barriers for the [0001]/[111] interface.

  • 137.
    El Hamri, M.
    et al.
    Univ Moulay Ismail, Unite CNRST URAC 08, LP2MS, Phys Dept,Fac Sci, BP 11201, Meknes, Morocco..
    Bouhou, S.
    Univ Moulay Ismail, Unite CNRST URAC 08, LP2MS, Phys Dept,Fac Sci, BP 11201, Meknes, Morocco..
    Essaoudi, I.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Univ Moulay Ismail, Unite CNRST URAC 08, LP2MS, Phys Dept,Fac Sci, BP 11201, Meknes, Morocco..
    Ainane, A.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Univ Moulay Ismail, Unite CNRST URAC 08, LP2MS, Phys Dept,Fac Sci, BP 11201, Meknes, Morocco.;Max Planck Inst Phys Complexer Syst, Nothnitzer Str 38, D-01187 Dresden, Germany..
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    A theoretical study of the hysteresis behaviors of a transverse spin-1/2 Ising nanocube2016In: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 413, p. 30-38Article in journal (Refereed)
    Abstract [en]

    The applied magnetic field dependencies of the surface shell, core and total magnetizations of a transverse spin -I Ising nanocube are investigated within the effective -field theory with correlations, based on the probability distribution technique, for both ferro- and antiferromagnetic exchange interactions. We have found that interfacial coupling has a strong effect on the shape and the number of hysteresis loops and also on the coercive field and remanent magnetization behaviors. Furthermore, when the temperature exceeds a critical one, the coercivities of the core, the surface shell and the system become zero.

  • 138.
    El Hamri, M.
    et al.
    Univ Moulay Ismail, CNRST URAC 08, Lab Phys Mat & Modelisat Syst LP2MS, Fac Sci,Phys Dept, BP 11201, Meknes, Morocco..
    Bouhou, S.
    Univ Moulay Ismail, CNRST URAC 08, Lab Phys Mat & Modelisat Syst LP2MS, Fac Sci,Phys Dept, BP 11201, Meknes, Morocco..
    Essaoudi, I.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Ainane, A.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Dujardin, F.
    Univ Lorraine, LCP A2MC, Inst Chim Phys & Mat, 1 Bd Arago, F-57070 Metz, France..
    Hysteresis loop behaviors of a decorated double-walled cubic nanotube2017In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 524, p. 137-143Article in journal (Refereed)
    Abstract [en]

    The effect of surface shell parameters on the hysteresis loop behaviors of a decorated Ising cubic nanotube, consisting of a ferromagnetic spin-12 core which is interacting ferrimagnetically with a ferromagnetic spin-1 surface shell, is investigated, in the present work, within the effective-field theory with correlations based on the probability distribution technique. We have found that these parameters have a strong effect on the shape and the number of hysteresis loops and also on the coercive field and remanent magnetization behaviors. Indeed, triple, quintuple, septuple and nonuple hysteresis loop patterns have also been observed.

  • 139.
    El Hamri, M.
    et al.
    Univ Moulay Ismail, LP2MS, Fac Sci, CNRST URAC 08,Unite Associee,Phys Dept, BP 11201, Meknes, Morocco..
    Bouhou, S.
    Univ Moulay Ismail, LP2MS, Fac Sci, CNRST URAC 08,Unite Associee,Phys Dept, BP 11201, Meknes, Morocco..
    Essaoudi, I.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Univ Moulay Ismail, LP2MS, Fac Sci, CNRST URAC 08,Unite Associee,Phys Dept, BP 11201, Meknes, Morocco..
    Ainane, Abdelmajid
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Univ Moulay Ismail, LP2MS, Fac Sci, CNRST URAC 08,Unite Associee,Phys Dept, BP 11201, Meknes, Morocco.;Max Planck Inst Phys Complexer Syst, Nothnitzer Str 38, D-01187 Dresden, Germany.; Univ Lorraine, LCP A2MC, Inst Chim Phys & Mat, 1 Bd Arago, F-57070 Metz, France..
    Ahuja, R
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Dujardin, F.
    Univ Lorraine, LCP A2MC, Inst Chim Phys & Mat, 1 Bd Arago, F-57070 Metz, France..
    Magnetic behaviors of a transverse spin-1/2 Ising cubic nanowire with core/shell structure2017In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 507, p. 51-60Article in journal (Refereed)
    Abstract [en]

    The surface shell exchange coupling effect on the magnetic properties (surface shell, core, total longitudinal and total transverse magnetizations, susceptibility, phase diagram and hysteresis loops) of a transverse spin-1/2 Ising cubic nanowire is investigated, in the present work, by employing the effective-field theory based on the probability distribution technique with correlations, for both ferro-and antiferromagnetic cases. We have found that this parameter has a strong effect on the magnetic properties in both cases. In the ferromagnetic case, the total longitudinal magnetization curves display Q-and S-type behaviors and the hysteresis loop has just one loop, whereas in the antiferromagnetic case, the N-type behavior, in which one compensation temperature appears below the critical temperature, exists in the total longitudinal magnetization curve versus reduced temperature, and triple hysteresis loops are found. The effect of applied field is also investigated on the total longitudinal magnetization for the both cases, and we have found that a large applied field value can overcome the antiferromagnetic coupling leading to a ferromagnetic-like behavior.

  • 140. El Hamri, M.
    et al.
    Bouhou, S.
    Essaoudi, I.
    Ainane, Abdelmajid
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Investigation of the surface shell effects on the magnetic properties of a transverse antiferromagnetic Ising nanocube2015In: Superlattices and Microstructures, ISSN 0749-6036, E-ISSN 1096-3677, Vol. 80, p. 151-168Article in journal (Refereed)
    Abstract [en]

    The effective-field theory (EFT) with correlations based on the probability distribution technique has been used to study the magnetic properties of an antiferromagnetic cubic nanoparticle (nanocube). We have found that the surface shell parameters have strong effects on the compensation temperature, the magnetization profiles, coercivity, the shape and the number of the hysteresis loops for certain parameters. The effect of reduced temperature has also been examined on the hysteresis loops.

  • 141.
    El Hamri, M.
    et al.
    Univ Moulay Ismail, LP2MS, Unite Associee CNRST URAC 08, Dept Phys,Fac Sci, Meknes, Morocco..
    Bouhou, S.
    Univ Moulay Ismail, LP2MS, Unite Associee CNRST URAC 08, Dept Phys,Fac Sci, Meknes, Morocco..
    Essaoudi, I.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Univ Moulay Ismail, LP2MS, Unite Associee CNRST URAC 08, Dept Phys,Fac Sci, Meknes, Morocco..
    Ainane, Abdelmajid
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Univ Moulay Ismail, LP2MS, Unite Associee CNRST URAC 08, Dept Phys,Fac Sci, Meknes, Morocco.;Max Planck Inst Phys Complexer Syst, D-01187 Dresden, Germany..
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Magnetic properties of a diluted spin-1/2 Ising nanocube2016In: Physica A: Statistical Mechanics and its Applications, ISSN 0378-4371, E-ISSN 1873-2119, Vol. 443, p. 385-398Article in journal (Refereed)
    Abstract [en]

    The effective-field theory with correlations based on the probability distribution technique is used to investigate the magnetic properties of a diluted Ising nanocube consisting of a ferromagnetic spin-1/2 core which is interacting antiferromagnetically with a ferromagnetic spin-1/2 surface shell. The effect of the concentration of magnetic atoms is examined. A number of interesting phenomena have been found such as the existence of the compensation temperature and triple hysteresis loops.

  • 142.
    El Hamri, M.
    et al.
    Univ Moulay Ismail, Unite Associee CNRST URAC 08, LP2MS, BP 11201, Meknes, Morocco..
    Bouhou, S.
    Univ Moulay Ismail, Unite Associee CNRST URAC 08, LP2MS, BP 11201, Meknes, Morocco..
    Essaoudi, I.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Univ Moulay Ismail, Unite Associee CNRST URAC 08, LP2MS, BP 11201, Meknes, Morocco..
    Ainane, Abdelmajid
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Univ Moulay Ismail, Unite Associee CNRST URAC 08, LP2MS, BP 11201, Meknes, Morocco.;Max Planck Inst Phys Complexer Syst, Nothnitzer Str 38, D-01187 Dresden, Germany..
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Magnetic Properties of a Diluted Transverse Spin-1 Ising Nanocube with a Longitudinal Crystal-Field2017In: INTERNATIONAL SYMPOSIUM ON CLUSTERS AND NANOMATERIALS / [ed] Jena, P Kandalam, AK, SPIE-INT SOC OPTICAL ENGINEERING , 2017, article id UNSP 1017409-1Conference paper (Refereed)
    Abstract [en]

    In the present work, the effective field theory with correlations based on the probability distribution technique has been used to investigate the effect of the surface shell longitudinal cristal field on the magnetic properties of a diluted antiferromagnetic spin-1 Ising nanocube particle. This effect has also been studied on the hysteresis loops of the system. It is found that this parameter has a strong effect on the magnetization profiles, compensation temperature, coercive field and remanent magnetization.

  • 143.
    El Hamri, M.
    et al.
    Univ Moulay Ismail, Fac Sci, Dept Phys,Unite Associee CNRST URAC 08, Lab Phys Mat & Modelisat Syst LP2MS, BP 11201, Meknes, Morocco..
    Bouhou, S.
    Univ Moulay Ismail, Fac Sci, Dept Phys,Unite Associee CNRST URAC 08, Lab Phys Mat & Modelisat Syst LP2MS, BP 11201, Meknes, Morocco..
    Essaoudi, I.
    Univ Moulay Ismail, Fac Sci, Dept Phys,Unite Associee CNRST URAC 08, Lab Phys Mat & Modelisat Syst LP2MS, BP 11201, Meknes, Morocco..
    Ainane, Abdelmajid
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Univ Moulay Ismail, Fac Sci, Dept Phys,Unite Associee CNRST URAC 08, Lab Phys Mat & Modelisat Syst LP2MS, BP 11201, Meknes, Morocco.;Max Planck Inst Phys Complexer Syst, Nothnitzer Str 38, D-01187 Dresden, Germany..
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Dujardin, F.
    ICPM, Lab Chim & Phys LCP A2MC, 1 Bd Arago, F-57070 Metz, France..
    Phase diagrams of a transverse cubic nanowire with diluted surface shell2016In: Applied Physics A: Materials Science & Processing, ISSN 0947-8396, E-ISSN 1432-0630, Vol. 122, no 3, article id 202Article in journal (Refereed)
    Abstract [en]

    The effective-field theory with correlations based on the probability distribution technique has been used to investigate the phase diagrams (critical and compensation temperatures) of a transverse antiferromagnetic spin-1/2 Ising cubic nanowire with diluted surface shell. It is found that the phase diagrams of the system are strongly affected by the surface shell parameters. Indeed, two compensation points appear for certain values of Hamiltonian parameters, and the range of appearance of these latter points depends strongly on the surface shell transverse field.

  • 144.
    El Hamri, M.
    et al.
    Univ Moulay Ismail, Dept Phys, Fac Sci, LP2MS,Unite Associee CNRST URAC 08, BP 11201, Meknes, Morocco..
    Bouhou, S.
    Univ Moulay Ismail, Dept Phys, Fac Sci, LP2MS,Unite Associee CNRST URAC 08, BP 11201, Meknes, Morocco..
    Essaoudi, I.
    Univ Moulay Ismail, Dept Phys, Fac Sci, LP2MS,Unite Associee CNRST URAC 08, BP 11201, Meknes, Morocco..
    Ainane, Abdelmajid
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Univ Moulay Ismail, Dept Phys, Fac Sci, LP2MS,Unite Associee CNRST URAC 08, BP 11201, Meknes, Morocco.;Max Planck Inst Phys Complexer Syst, Nothnitzer Str 38, D-01187 Dresden, Germany.;Univ Lorraine, LCP A2MC, Inst Chim Phys & Mat, 1 Bd Arago, F-57070 Metz, France..
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Dujardin, F.
    Univ Lorraine, LCP A2MC, Inst Chim Phys & Mat, 1 Bd Arago, F-57070 Metz, France..
    Some characteristic behaviours of a spin-1/2 Ising nanoparticle2016In: 3Rd Euro-Mediterranean Conference On Materials And Renewable Energies (Emcmre-3), IOP PUBLISHING LTD , 2016, article id UNSP 012023Conference paper (Refereed)
    Abstract [en]

    By using the effective-field theory with correlations based on the probability distribution technique; the magnetization, susceptibility, internal energy, specific heat and the free energy expressions for a ferromagnetic spin-1/2 Ising nanoparticle have been developed and calculated numerically for different surface shell exchange coupling parameter. A number of interesting phenomena have been observed, depending on the surface shell exchange coupling term.

  • 145.
    El Hamri, M.
    et al.
    Univ Moulay, Fac Sci, Unite Associee CNRST URAC 08, Syst,LP2MS,Dept Phys,Lab Phys Mat & Modelisat, Ismail, Meknes, Morocco..
    Bouhou, S.
    Univ Moulay, Fac Sci, Unite Associee CNRST URAC 08, Syst,LP2MS,Dept Phys,Lab Phys Mat & Modelisat, Ismail, Meknes, Morocco..
    Essaoudi, I.
    Univ Moulay, Fac Sci, Unite Associee CNRST URAC 08, Syst,LP2MS,Dept Phys,Lab Phys Mat & Modelisat, Ismail, Meknes, Morocco..
    Ainane, Abdelmajid
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Univ Moulay, Fac Sci, Unite Associee CNRST URAC 08, Syst,LP2MS,Dept Phys,Lab Phys Mat & Modelisat, Ismail, Meknes, Morocco.;Max Planck Inst Phys Complexer Syst, D-01187 Dresden, Germany..
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Dujardin, F.
    ICPM, LCPMC, F-57070 Metz, France..
    Thermodynamic Properties of the Core/Shell Antiferromagnetic Ising Nanocube2015In: Journal of Superconductivity and Novel Magnetism, ISSN 1557-1939, E-ISSN 1557-1947, Vol. 28, no 10, p. 3127-3133Article in journal (Refereed)
    Abstract [en]

    Using the effective field theory with correlations, the effects of the exchange interaction on the thermal behaviors of the total magnetization, internal energy, specific heat, entropy, and free energy of a transverse antiferromagnetic Ising nanocube are investigated. The phase diagram is also calculated and discussed in detail.

  • 146.
    Emanuelsson, Rikard
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Physical Organic Chemistry.
    Löfås, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Wallner, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Physical Organic Chemistry. Institut für Anorganische Chemie, Technische Universität Graz.
    Nauroozi, Djawed
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Baumgartner, Judith
    Institut für Anorganische Chemie, Technische Universität Graz.
    Marschner, Christoph
    Institut für Anorganische Chemie, Technische Universität Graz.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ott, Sascha
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Grigoriev, Anton
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ottosson, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Physical Organic Chemistry.
    Configuration- and Conformation-Dependent Electronic Structure Variations in 1,4-Disubstituted Cyclohexanes Enabled by a Carbon-to-Silicon Exchange2014In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 20, no 30, p. 9304-9311Article in journal (Other academic)
    Abstract [en]

    Cyclohexane, with its well-defined conformers, could be an ideal force-controlled molecular switch if it were to display substantial differences in electronic and optical properties between its conformers. We utilize sigma conjugation in heavier analogues of cyclohexanes (i.e. cyclohexasilanes) and show that 1,4-disubstituted cyclohexasilanes display configuration-and conformation-dependent variations in these properties. Cis- and trans-1,4-bis(trimethylsilylethynyl)-cyclohexasilanes display a 0.11 V difference in their oxidation potentials (computed 0.11 V) and a 0.34 eV difference in their lowest UV absorption (computed difference between first excitations 0.07 eV). This is in stark contrast to differences in the corresponding properties of analogous all-carbon cyclohexanes (computed 0.02 V and 0.03 eV, respectively). Moreover, the two chair conformers of the cyclohexasilane trans isomer display large differences in electronic-structure-related properties. This enables computational design of a mechanically force-controlled conductance switch with a calculated single-molecule ON/OFF ratio of 213 at zero-bias voltage.

  • 147.
    Emanuelsson, Rikard
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Physical Organic Chemistry.
    Löfås, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Zhu, Jun
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Physical Organic Chemistry. State Key Laboratory of Physical Chemistry of Solid Surfaces, Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Grigoriev, Anton
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ottosson, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Physical Organic Chemistry.
    In Search of Flexible Molecular Wires with Near Conformer-Independent Conjugation and Conductance: A Computational Study2014In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 118, no 11, p. 5637-5649Article in journal (Refereed)
    Abstract [en]

    Oligomers of 1,4-disila/germa/stannacyclohexa-2,5-dienes as well as all-carbon 1,4-cyclohexadienes connected via E—E single bonds (E = C, Si, Ge, or Sn) were studied through quantum chemical calculations in an effort to identify conformationally flexible molecular wires that act as molecular “electrical cords” having conformer-independent conjugative and conductive properties. Our oligomers display neutral hyperconjugative interactions (σ/π-conjugation) between adjacent σ(E—E) and π(C═C) bond orbitals, and these interactions do not change with conformation. The energies and spatial distributions of the highest occupied molecular orbitals of methyl-, silyl-, and trimethylsilyl (TMS)-substituted 1,4-disilacyclohexa-2,5-diene dimers, and stable conformers of trimers and tetramers, remain rather constant upon Si–Si bond rotation. Yet, steric congestion may be a concern in some of the oligomer types. The calculated conductances for the Si-containing tetramers are similar to that of a σ-conjugated linear all-anti oligosilane (a hexadecasilane) with equally many bonds in the conjugated paths. Moreover, the Me-substituted 1,4-disilacyclohexadiene tetramer has modest conductance fluctuations with Si–Si bond rotations when the electrode–electrode distance is locked (variation by factor 30), while the fluctuations under similar conditions are larger for the analogous TMS-substituted tetramer. When the electrode–electrode distance is changed several oligomers display small conductance variations within certain distance intervals, e.g., the mean conductance of TMS-substituted 1,4-disilacyclohexa-2,5-diene tetramer is almost unchanged over 9 Å of electrode–electrode distances.

  • 148.
    Fang, C. M.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Prediction of MAX phases, VN+1SiCN (N=1,2), from first-principles theory2007In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 101, no 1, p. 013511-Article in journal (Refereed)
    Abstract [en]

    We have investigated the phase stability of two MAX phases, V3SiC2 and V2SiC, by means of first-principles total-energy calculations within the generalized-gradient approximation and the projector-augmented wave method. The theoretical bulk modulus of V3SiC2 is 219 GPa, which is similar to 17% larger than that of Ti3SiC2 (187 GPa). The total-energy calculations show that V2SiC is stable with a formation energy of about 0.27 eVf.u. and that V3SiC2 is metastable (only 0.02 eVf.u. is required to stabilize this phase from its competing phases). We suggest that both these two MAX compounds should be possible to synthesize as stable (or metastable) phases using, e.g., thin-film deposition.

  • 149.
    Fang, Changming
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Condensed Matter Theory.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Condensed Matter Theory.
    Local structure and electronic-spin transition of Fe-bearing MgSiO3 perovskite under conditions of the Earth's lower mantle2008In: Physics of the Earth and Planetary Interiors, ISSN 0031-9201, E-ISSN 1872-7395, Vol. 166, no 1-2, p. 77-82Article in journal (Refereed)
    Abstract [en]

    We report first-principles electronic structure calculations on the structural and electronic-spin behaviours of Fe-bearing MgSiO3 crystals up to the pressure of Earth's mantle. The transition pressure of the Fe-bearing MgSiO3 from the orthorhombic perovskite (OPv) to the orthorhombic post-perovskite (OPPv) phase decreases with increasing Fe concentration. The lattice distortion has impacts on the electronic-spin behaviour of the Fe ions in the PVs. The spin-polarizations of the Fe ions in the (Fe,Mg)SiO3 OPvs and OPPvs keep unchanged up to the pressures in the lower mantle. Meanwhile, the Fe-bearing MgSiO3 OPV Containing Fe-Mg-Fe-Si pairs exhibits multiple-magnetic moments co-existing in a large pressure range (from about 78 to 110 GPa), and finally becomes non-magnetic at pressure higher than 110 GPa. These results provide a mechanism to understand the recent experimental results about Fe valence states and the electronic transitions of the Fe-bearing MgSiO3 under high pressure.

  • 150.
    Fang, Chang-Ming
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Structures and stability of ABO(3) orthorhombic perovskites at the Earth's mantle conditions from first-principles theory2006In: Physics of the Earth and Planetary Interiors, ISSN 0031-9201, E-ISSN 1872-7395, Vol. 157, no 1-2, p. 1-7Article in journal (Refereed)
    Abstract [en]

    We report first-principles calculations on the structures and stabilities of the ABO(3) (A = Mg and Ca; B = Si and Ge) orthorhombic perovskites (OPvs) under high pressures. Calculations have also been performed for CdGeO3 and CdTiO3 OPvs. The calculations showed that MgSiO3, MgGeO3, CaGeO3, CdGeO3 and CdTiO3 OPvs transform to the orthorhombic post-perovskites (OPPvs) at about 10 1, 47, 55, 78 and 64 GPa, respectively, while CaSiO3 OPv is stable under high pressures. The theoretical results are in good agreement with the available experiments. The lattice distortions with pressure have been studied by analyzing the lattice deviations from the corresponding cubic perovskite (CPv). The lattice distortions increase with pressure for MgSiO3, MgGeO3, CaGeO3 and CdTiO3 OPvs, while CaSiO3 OPv has very small lattice distortions under high-pressures and the lattice distortions of CdGeO3 OPV even decrease with increasing pressure. The OPPvs have large distortions for the a-axis (about -10%).

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