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  • 1.
    Aguirre Castillo, José
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Optimisation of the bottom stirring praxis in a LD-LBE converter: Investigations and tests on phosphorous removal, nitrogen as stirring gas, and slopping2015Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The LD-process, called after the cities Linz and Donawitz, is used to convert pig iron into crude steel by blowing oxygen on top of the pig iron. A LD-LBE converter, Lance Bubbling Equilibrium, also stirs the melt trough a bottom stirring system.

    The bottom stirring in a LD-LBE converter is believed to have a positive effect alone on the phosphorous removal. Previous studies have shown that the temperature and slag composition are the main factors affecting phosphorus removal. Phosphorus binds to the slag easier at low temperature and to slag with certain levels of dissolved calcium (a process additive). Different praxes were tested and a better dephosphorisation was reached. The bottom stirrings effect on the dissolution of calcium additives is a possible explanation to the results and mechanisms presented in this study.

    The study also aimed to investigate the use of nitrogen as stirring gas instead of argon. Nitrogen is removed from the steel during the formation of carbon oxide gases. Nitrogen was used in varying amounts as stirring gas during the first half of the oxygen blow. It proved to be safe to use as long as there was a high content of carbon in the melt. However using nitrogen beyond half of the blow showed to be risky for nitrogen sensible steels; even in small amounts since there is not enough carbon left to degas the steel from nitrogen.

    Slopping happens when formed gas from the LD-process is trapped in the slag. The slag level rises and sometimes it floods the converter resulting in yield losses. The influence of the bottom stirring on slopping was studied, which resulted in the conclusion that slopping cannot be avoided by simply improving the bottom stirring.

    Although some verification studies remains to be done, if the suggestions based on the results of this thesis were employed, savings in the oxygen and stirring gas economies could be made. Not least improvements on the iron yield.

  • 2.
    Ahlberg, Patrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Johansson, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Zhang, Zhibin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Lindblad, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Nyberg, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Defect formation in graphene during low-energy ion bombardment2016In: APL Materials, ISSN 2166-532X, Vol. 4, no 4, article id 046104Article in journal (Refereed)
    Abstract [en]

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

  • 3.
    Ahlberg, Patrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Nyberg, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Zhi-Bin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Toward synthesis of oxide films on graphene with sputtering based processes2016In: Journal of Vacuum Science & Technology B, ISSN 1071-1023, E-ISSN 1520-8567, Vol. 34, no 4, article id 040605Article in journal (Refereed)
    Abstract [en]

    The impact of energetic particles associated with a sputter deposition process may introduce damage to single layer graphene films, making it challenging to apply this method when processing graphene. The challenge is even greater when oxygen is incorporated into the sputtering process as graphene can be readily oxidized. This work demonstrates a method of synthesizing ZnSn oxide on graphene without introducing an appreciable amount of defects into the underlying graphene. Moreover, the method is general and applicable to other oxides. The formation of ZnSn oxide is realized by sputter deposition of ZnSn followed by a postoxidation step. In order to prevent the underlying graphene from damage during the initial sputter deposition process, the substrate temperature is kept close to room temperature, and the processing pressure is kept high enough to effectively suppress energetic bombardment. Further, in the subsequent postannealing step, it is important not to exceed temperatures resulting in oxidation of the graphene. The authors conclude that postoxidation of ZnSn is satisfactorily performed at 300 degrees C in pure oxygen at reduced pressure. This process results in an oxidized ZnSn film while retaining the initial quality of the graphene film.

  • 4.
    Almquist, Martin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Numerical Analysis.
    Mattsson, Ken
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Numerical Analysis.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    High-fidelity numerical solution of the time-dependent Dirac equation2014In: Journal of Computational Physics, ISSN 0021-9991, E-ISSN 1090-2716, Vol. 262, p. 86-103Article in journal (Refereed)
  • 5.
    Almquist, Martin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Numerical Analysis.
    Mattsson, Ken
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Numerical Analysis.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Stable and accurate simulation of phenomena in relativistic quantum mechanics2013In: Proc. 11th International Conference on Mathematical and Numerical Aspects of Waves, Tunisia: ENIT , 2013, p. 213-214Conference paper (Other academic)
  • 6.
    Andersson, Claes-Henrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Physical Organic Chemistry.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Grennberg, Helena
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Physical Organic Chemistry.
    Synthesis and characterization of a ferrocene-linked bis-fullerene[60] dumbbell2012In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 41, no 8, p. 2374-2381Article in journal (Refereed)
    Abstract [en]

    A new [60]fullerene dumbbell consisting of two fulleropyrrolidines connected to a central ferrocene unit by amide linkages has been prepared and fully characterized by elemental analysis, 1H NMR, UV/Vis, fluorescence and mass spectrometry. The electrochemical properties as determined by cyclic voltammetry show ground state electronic communication between the ferrocene and the fullerene units. In addition, the preparaton of a ferrocene building block for an alternative linking approach is presented.

  • 7.
    Andersson, Matilda
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Högström, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Urbonaite, Sigita
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Furlan, Andrej
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Deposition and characterization of magnetron sputtered amorphous Cr-C films2012In: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 86, no 9, p. 1408-1416Article in journal (Refereed)
    Abstract [en]

    Thin films in the Cr-C system with carbon content of 25-85 at.% have been deposited using non-reactive DC magnetron sputtering from elemental targets. Analyses with X-ray diffraction and transmission electron microscopy confirm that the films are completely amorphous. Also, annealing experiment show that the films had not crystallized at 500 degrees C. Furthermore, X-ray spectroscopy and Raman spectroscopy show that the films consist of two phases, an amorphous CrCx phase and an amorphous carbon (a-C) phase. The presence of two amorphous phases is also supported by the electrochemical analysis, which shows that oxidation of both chromium and carbon contributes to the total current in the passive region. The relative amounts of these amorphous phases influence the film properties. Typically, lower carbon content with less a-C phase leads to harder films with higher Young's modulus and lower resistivity. The results also show that both films have lower currents in the passive region compared to the uncoated 316L steel substrate. Finally, our results were compared with literature data from both reactively and non-reactively sputtered chromium carbide films. The comparison reveals that non-reactive sputtering tend to favour the formation of amorphous films and also influence e.g. the sp(2)/sp(3) ratio of the a-C phase. 

  • 8.
    Andersson, Matilda
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Urbonaite, Sigita
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Lewin, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Magnetron sputtering of Zr-Si-C thin films2012In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 520, no 20, p. 6375-6381Article in journal (Refereed)
    Abstract [en]

    The phase composition and chemical bonding of Zr-C and Zr-Si-C films deposited by magnetron sputtering has been studied. The results show that the binary Zr-C films at higher carbon contents form nanocrystallites of ZrC in an amorphous carbon matrix. The addition of Si induces a complete amorphization of the films above a critical concentration of about 15 at.%. X-ray diffraction and transmission electron microscopy confirm that the amorphous films contain no nanocrystallites and therefore can be described as truly amorphous carbides. The amorphous films are thermally stable but start to crystallize above 500 degrees C. Analysis of the chemical bonding with X-ray photoelectron spectroscopy suggests that the amorphous films exhibit a mixture of different chemical bonds such as Zr-C, Zr-Si and Si-C and that the electrical and mechanical properties are dependent on the distribution of these bonds. For higher carbon contents, strong Si-C bonds are formed in the amorphous Zr-Si-C films making them harder than the corresponding binary Zr-C films.

  • 9.
    Andersson, Sara
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Förutsättningar att utforma stationsbatterier i vattenkraftverk med Li-jonteknik2015Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In hydropower plants it is necessary to always have local power supply. Therefore, the plants are equipped with batteries as stationary back up power. Vattenfall Vattenkraft is using lead acid batteries but has been investigating alternatives to replace them. The aim of this study is to investigate the potential of using Li-ion technology as back up power.

    The study showed that Li-ion batteries have many qualities. The Li-ion technology will decrease the space and maintenance demand. The technology also eliminates many of the personal safety risks that lead acid batteries may cause. Unfortunately overcharging or overheating the Li-ion battery may result in fire or explosion. Those risks are reduced by an electronic battery management system and mechanical protection.

    The result from the cost comparison between the two battery technologies showed that the maintenance costs decreases with 70 % when using Li-ion battery. The purchase cost of Li-ion batteries is almost three times higher compared to lead acid batteries. But prices will probably drop drastically in the coming years.

    According to this study Li-ion has great potential to replace the lead acid battery.  Vattenfall Vattenkraft should wait until the technology develops further and prices decrease before any larger installations are made. But small installations should be considered in order to get more experience of the technology.

     

  • 10.
    Andersson, Y
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Rundqvist, S
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Beckman, O
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Lundgren, L
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Nordblad, P
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Properties of Fe2 P crystals prepared from a liquid copper medium1978In: Physica status solidi. A, Applied research, ISSN 0031-8965, E-ISSN 1521-396X, Vol. 49, no 2, p. K153-K156Article in journal (Refereed)
  • 11.
    Asfaw, Habtom D.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Valvo, Mario
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Maibach, Julia
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Ångström, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Tai, Cheuk-Wai
    Bacsik, Zoltan
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Boosting the thermal stability of emulsion–templated polymers via sulfonation: an efficient synthetic route to hierarchically porous carbon foams2016In: ChemistrySelect, ISSN 2365-6549, Vol. 1, no 4, p. 784-792Article in journal (Refereed)
    Abstract [en]

    Hierarchically porous carbon foams with specific surface areas exceeding 600 m2 g−1 can be derived from polystyrene foams that are synthesized via water-in-oil emulsion templating. However, most styrene-based polymers lack strong crosslinks and are degraded to volatile products when heated above 400 oC. A common strategy employed to avert depolymerization is to introduce potential crosslinking sites such as sulfonic acids by sulfonating the polymers. This article unravels the thermal and chemical processes leading up to the conversion of sulfonated high internal phase emulsion polystyrenes (polyHIPEs) to sulfur containing carbon foams. During pyrolysis, the sulfonic acid groups (-SO3H) are transformed to sulfone (-C-SO2-C-) and then to thioether (-C−S-C-) crosslinks. These chemical transformations have been monitored using spectroscopic techniques: in situ IR, Raman, X-ray photoelectron and X-ray absorption near edge structure spectroscopy. Based on thermal analyses, the formation of thioether links is associated with increased thermal stability and thus a substantial decrease in volatilization of the polymers.

  • 12.
    Asfaw, Habtom Desta
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Roberts, Matthew R.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Tai, Cheuk-Wai
    Stockholm University.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. DTU.
    Valvo, Mario
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Nanosized LiFePO4-decorated emulsion-templated carbon foam for 3D micro batteries: a study of structure and electrochemical performance2014In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 6, no 15, p. 8804-8813Article in journal (Refereed)
    Abstract [en]

    In this article, we report a novel 3D composite cathode fabricated from LiFePO4 nanoparticles deposited conformally on emulsion-templated carbon foam by a sol–gel method. The carbon foam is synthesized via a facile and scalable method which involves the carbonization of a high internal phase emulsion (polyHIPE) polymer template. Various techniques (XRD, SEM, TEM and electrochemical methods) are used to fully characterize the porous electrode and confirm the distribution and morphology of the cathode active material. The major benefits of the carbon foam used in our work are closely connected with its high surface area and the plenty of space suitable for sequential coating with battery components. After coating with a cathode material (LiFePO4nanoparticles), the 3D electrode presents a hierarchically structured electrode in which a porous layer of the cathode material is deposited on the rigid and bicontinuous carbon foam. The composite electrodes exhibit impressive cyclability and rate performance at different current densities affirming their importance as viable power sources in miniature devices. Footprint area capacities of 1.72 mA h cm−2 at 0.1 mA cm−2 (lowest rate) and 1.1 mA h cm−2 at 6 mA cm−2(highest rate) are obtained when the cells are cycled in the range 2.8 to 4.0 V vs. lithium.

  • 13.
    Asfaw, Habtom Desta
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Tai, Cheuk-Wai
    Stockholm University.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Emulsion-templated graphitic carbon foams with optimum porosity for 3D Li-ion microbatteriesManuscript (preprint) (Other academic)
  • 14.
    Asfaw, Habtom Desta
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Tai, Cheuk-Wai
    Stockholm Univ, Arrhenius Lab, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden..
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Over-Stoichiometric NbO2 Nanoparticles for a High Energy and Power Density Lithium Microbattery2017In: CHEMNANOMAT, ISSN 2199-692X, Vol. 3, no 9, p. 646-655Article in journal (Refereed)
    Abstract [en]

    Effective utilization of active materials in microbatteries can be enhanced by rational design of the electrodes. There is an increasing trend of using 3D electrodes that are coated in nanosized active materials to boost both energy and power densities. This article focuses on the fabrication of 3D electrodes based on monolithic carbon foams coated in over-stoichiometric NbO2 nanoparticles. The electrodes exhibit remarkable energy and power densities at various current densities when tested in lithium microbatteries. An areal capacity of around 0.7mAhcm(-2) and energy density up to 45mWhcm(-3) have been achieved. More than half of the areal capacity can be accessed at a current density of about 11mAcm(-2), with the corresponding energy and power densities being 21mWhcm(-3) and 1349mWcm(-3). These values are comparable to those of microsupercapacitors containing carbon and MnO2 nanomaterials. Furthermore, the electrochemical reversibility improves progressively upon cycling along with substantial increase in the charge transfer kinetics of the electrode. Based on impedance analyses almost a fourfold decrease in the charge transfer resistance has been observed over 25 cycles. Such enhancement of the electronic properties of NbO2 can account for the high electrochemical rate performance of the 3D electrodes.

  • 15.
    Asfaw, Habtom Desta
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Tai, Cheuk-Wai
    Stockholm University.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Surface-oxidized NbO2 nanoparticles for high performance lithium microbatteriesManuscript (preprint) (Other academic)
  • 16.
    Asfaw, Habtom
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Tai, Cheuk-Wai
    Stockholm University.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Surface-oxidized NbO2 nanoparticles for high performance lithium microbatteriesManuscript (preprint) (Other academic)
  • 17.
    Backe, Kalle
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Functionalization of graphene for biosensor-applications2014Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This project investigates the interaction of water with graphene and graphane. It also examines how the functionalization with polystyrene will affect the surfaces and their interaction with water. This study is completely theoretical and is performed with the simulating and modeling software called Materials Studio from Accelrys, Inc. Calculations are done with CASTEP, Dmol3 and Forcite. It is important to gain a deep understanding about the interactions between graphene (or graphane) surfaces and the water that is attached to it, since these materials are of a large interest for biosensor applications.

    The conclusion is that graphane (compared to graphene) is more susceptible to functionalization with styrene. This is most probably due to the sp3 hybridization of the C atoms, so one has to hydrogenate the graphene surface to make it more functionalizable. The graphane surface are also more hydrophilic than graphene. However, by functionalization with styrene it is possible to make both surfaces more hydrophilic and thus more suitable for biological system. Further investigations need to be done in order to validate these results.

  • 18.
    Barker, Paul Michael
    et al.
    Laboratory for Nanoscale Materials Science, Empa, Dübendorf, Switzerland.
    Konstantinidis, Stephanos
    Chimie des Interactions Plasma-Surface (ChIPS), Université de Mons, Belgium.
    Lewin, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Britun, Nikolay
    Chimie des Interactions Plasma-Surface (ChIPS), Université de Mons, Belgium.
    Patscheider, Jörg
    Laboratory for Nanoscale Materials Science, Empa, Dübendorf, Switzerland.
    An investigation of c-HiPIMS discharges during titanium deposition2014In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 258, p. 631-638Article in journal (Refereed)
    Abstract [en]

    Abstract A modified version of high power impulse magnetron sputtering (HiPIMS) has been used to deposit titanium films at higher deposition rates than for conventional HiPIMS whilst maintaining similar pulse voltages and peak currents. This process, named chopped-HiPIMS (c-HiPIMS) utilises pulses decomposed into several short single pulses instead of single HiPIMS pulses. Experiments show that manipulating the pulse sequence during c-HiPIMS, i.e. the tÎŒon and tÎŒoff times (explained in the glossary) allows for an increase of the deposition rate; increases of up to 150% are reported here for selected conditions. Further, deposition rates higher than those measured using direct current magnetron sputtering are also shown. Investigations by optical emission and optical absorption spectroscopy at the substrate show that the increase of deposition rate is not a consequence of different ion concentrations arriving at the substrate when changing the micro-pulse-off times of c-HiPIMS. Thus alternative reasons for the enhanced deposition rate during c-HiPIMS deposition of metal films are discussed. It is demonstrated that film micro-structure maintains the void free, dense nature typically demonstrated by HiPIMS deposited coatings whilst at enhanced deposition rates. Thus c-HiPIMS allows for the preparation of dense films with the benefit of faster growth rates.

  • 19. Barker, Paul Michael
    et al.
    Lewin, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Patscheider, Jorg
    Modified high power impulse magnetron sputtering process for increased deposition rate of titanium2013In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 31, no 6, p. 060604-Article in journal (Refereed)
    Abstract [en]

    A modified version of high power impulse magnetron sputtering (HiPIMS) has been used to deposit titanium films at higher deposition rates than for conventional HiPIMS while maintaining similar pulse voltages and peak currents. In the present study, additional control parameters are explored through the chopping of the HiPIMS pulse into a pulse sequence. Experiments show that the use of sequences allows for an increase of the deposition rate of more than 45% compared to conventional HiPIMS. The increase in deposition rate is ascribed to a combination of reduced gas rarefaction effects, prevention of sustained self-sputtering, and a relaxation of ion trapping.

  • 20.
    BECKMAN, O
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    LUNDGREN, L
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    NORDBLAD, P
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    SANDLUND, L
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    SVEDLINDH, P
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    LUNDSTROM, T
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    RUNDQVIST, S
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    SPECIFIC-HEAT AND MAGNETIC-SUSCEPTIBILITY OF SINGLE-PHASE YBA2CU3O71987In: Physics Letters A, ISSN 0375-9601, E-ISSN 1873-2429, Vol. 125, p. 425-428Article in journal (Refereed)
  • 21.
    BECKMAN, O
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    LUNDGREN, L
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    NORDBLAD, P
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    SVEDLINDH, P
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    TORNE, A
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    ANDERSSON, Y
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    RUNDQVIST, S
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    SPECIFIC-HEAT OF THE FERROMAGNET FE2P1982In: Physica scripta. T, ISSN 0281-1847, Vol. 25, p. 679-681Article in journal (Refereed)
  • 22.
    Berg, Camilla
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Influence of Magnesium in theFormation of Phosphate Spheres: A simple method for the fabrication of sphericalparticles of calcium and magnesium phosphate2017Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Calcium phosphates and recently also magnesium phosphates, are used for medical applications, due to their biocompatibility and bioactivity. These properites makes spherical particles of calcium and magnesium phosphate suitable for carrier materials for drug delivery applications. By creating porous and/or hollow particles itis possible to load the particles with a drug and control therelease of the active substance.

    In this work, an ion-induced method for the synthesis of spherical calcium and magnesium phosphates was developed. A simple precipitation reaction was used, where substituting magnesium ions could replace the function of templates, such as surfactants or micelles, to induce the formation of spheres of a certain size and morphology.

    Experimental results showed that magnesium had an inhibitory effect on the nucleation and crystal growth of calcium phosphates. By using substituting ions as a structural regulator, it was possible to alter the size, morphology and phase composition of the spheres. At low magnesium concentrations, the spheres had a smooth surface andwere between 200 nanometer to 1 micrometer in diameter and composed of hydroxyapatite and/or magnesium-substituted beta-TCP. At higher magnesium concentrations, the spheres were about 10-50 micrometer with a rough, flaky surface. Results also proved that calcium ionshave the same effect on the crystallisation and self-assembly of magnesium phosphates. Apart from the magnesium concentration, reaction temperature proved to have a high influence on the sphereformation, whereas Ca/P ratio and reaction times above three hours did not affect the sphere formation to the same extent.

  • 23.
    Blom, Tobias
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Jafri, Hassan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Widenkvist, Erika
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Grennberg, Helena
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Quinlan, R A
    Holloway, B C
    Leifer, Klaus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    An In-Situ Prepared Nano-Manipulator Tip for Electrical Characterization of Free Standing Graphene Like Sheets Inside a Focused Ion Beam/Scanning Electron Microscope2011In: Journal of Nanoelectronics and Optoelectronics, ISSN 1555-130X, E-ISSN 1555-1318, Vol. 6, no 2, p. 162-168Article in journal (Refereed)
    Abstract [en]

    Although contacting and moving atoms has been demonstrated using probe techniques, for many nano-objects, a fast and reproducible nano-probe technique is needed to acquire a large number of electrical measurements on nano-objects that are often similar but not the identical. Nano-manipulators have become a common tool in many scanning electron microscopes (SEM) and focussed ion beam devices (FIB). They can be rapidly and reproducibly moved from one nano-object to another. In this work we present a procedure to obtain reproducible electrical measurements of nano- to micron-sized objects by using a sharp, tungsten tip with well defined surface properties. The tip is a part of a manipulator and is sharpened in-situ by using the gallium ion beam inside a focused ion beam/scanning electron microscope (FIB/SEM). The contact resistance between a Au surface and the tip is 70 kΩ before the sharpening procedure and 10 Ω after sharpening. The leakage current of the total set-up of 10pA makes it possible to measure currents through a variety of nano-objects. This measurement technique is applied to measure the resistance of as grown, water treated and two HCl treated carbon nanosheets (CNS). These CNS vary in size and morphology. Using this nano-contacting set-up, we could obtain measurements of more than 400 different CNS. The obtained histograms allow us to observe a clear decrease of the resistance between original and 3 hour acid treated CNSs. We observe that longer periods of exposure of the CNS to the HCl do not further modify the resistance.

  • 24.
    Boll, T.
    et al.
    Chalmers, Dept Appl Phys, SE-41296 Gothenburg, Sweden..
    Thuvander, M.
    Chalmers, Dept Appl Phys, SE-41296 Gothenburg, Sweden..
    Koch, S.
    Chalmers, Dept Appl Phys, SE-41296 Gothenburg, Sweden..
    Wagner, J. N.
    Karlsruhe Inst Technol, KNMF, DE-76344 Eggenstein Leopoldshafen, Germany..
    Nedfors, N.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Stiller, K.
    Chalmers, Dept Appl Phys, SE-41296 Gothenburg, Sweden..
    An APT investigation of an amorphous Cr-B-C thin film2015In: Ultramicroscopy, ISSN 0304-3991, E-ISSN 1879-2723, Vol. 159, p. 217-222Article in journal (Refereed)
    Abstract [en]

    A magnetron sputtered amorphous Cr-B-C thin film was investigated by means of atom probe tomography (APT). The film is constituted of two phases; a Cr-rich phase present as a few nanometer large regions embedded in a Cr-poor phase (tissue phase). The Cr-rich regions form columnar chains oriented parallel to the growth direction of the film. It was found that the Cr-rich regions have a higher B:C ratio than the Cr-poor regions. The composition of the phases was determined as approximately 35Cr-33B-30C and 15Cr-40B-42C (at%), respectively. The results suggest that this type of nanocomposite films has a more complex structure than previously anticipated, which may have an importance for the mechanical and electrical properties.

  • 25.
    Boman, Mats
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Berger, Rolf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Andersson, Yvonne
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Hahlin, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Björefors, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Ottosson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Corrosion of copper in water free from molecular oxygen2014In: Corrosion Engineering, Science and Technology, ISSN 1478-422X, E-ISSN 1743-2782, Vol. 49, no 6, p. 431-434Article in journal (Refereed)
    Abstract [en]

    The possibility of copper reacting with O-2-free water has been investigated by analysis of primary corrosion products, as well as by monitoring gas pressure change by time, in long term experiments for up to 6 months in a glove box environment. We establish hydrogen production, but being of the same magnitude irrespective whether copper is present or not. Although low, the hydrogen production rate is considerably larger than what would directly correspond to the amount of analysed copper oxidation products. Our analyses encompass the changes to the surface cleaned copper (99.9999%), the water phase and the Duran glass in contact with the water (ppt quality). We have used very sensitive methods (XPS, AES, ICP-MS, XRF) while keeping contamination risks to a minimum. We conclude that the oxidation rate of copper is very low, yielding only parts of a monolayer of Cu2O after 6 months of exposure at 50 degrees C together with an accompanying very low concentration of copper species (4-5 mu g L-1) in the water phase.

  • 26.
    Borg, Sebastian
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Synthetic bone grafts for treatment of femoral head necrosis2017Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Necrosis of the femoral head is a relatively common medical condition that radically

    decrease the quality of life for the patient. Left untreated it could lead to destruction

    of the hip joint. A common treatment is using bone autografts, also called bone chips.

    However, in the last decades synthetic bone grafts have become a very interesting

    alternative. This thesis had two aims; to evaulate how porous hydroxyapatite grafts

    with varied pore size could be produced by different size of the porogen and to

    create two-phase cements which would form pores in situ by using a dissolvable

    phase of calcium sulfate hemihydrate. The phase composition, morphology, porosity

    and pore size distribution were characterized with x-ray diffraction, scanning electron

    microscopy and micro-computed tomography. It was found that hydroxyapatite

    granules could be produced and it was possible to vary their pore size to some extent

    by changing the size of the porogen. At physiological temperature, pores were formed

    in the two-phase cements from one week and onwards.

  • 27.
    Böhme, Solveig
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Electrochemical behavior of tin(IV) oxide electrodes in lithium-ion batteries at elevated temperaturesManuscript (preprint) (Other academic)
  • 28.
    Böhme, Solveig
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Electrochemical behavior of tin(IV) oxide electrodes in lithium-ion batteries at high potentials2015Conference paper (Other academic)
    Abstract [en]

    In commercial lithium-ion batteries (LIB) graphite is used as the anode material. However, graphite has a rather limited volumetric and gravimetric capacity which is a drawback when higher energy densities are required as for instance in cars. Here, other materials with higher capacities and energy densities like the alloying materials tin and silicon are hence needed. Even bigger capacities could be obtained using tin oxide based compounds due to a combination of the tin oxide conversion reaction with lithium to tin and lithium oxide and the alloying reaction between tin and lithium. However, tin oxides usually suffer a great capacity loss after the first cycle due to the irreversibility of tin oxide reduction with lithium. [1,2] Nevertheless, there have been some reports in the past about a limited reversibility of the tin(IV) oxide conversion. [3-5]

    In our work we, therefore, investigated voltammetric cycling of tin(IV) oxide electrodes in different potential windows in order to learn about the influence of the alloying reaction on the conversion reaction (excluding the alloying reaction when cutting at 0.9 V vs. Li+/Li). In addition, rather high voltages (up to 3.7 V vs. Li+/Li) were applied to check the tin(IV) oxide conversion reversibility and electrode stability. Further cycling experiments were carried out at 60 oC and the results compared to cycling at room temperature. Cycling products at different potentials and temperatures were investigated using XPS. The results confirmed a certain reversibility of the tin(IV) oxide conversion which seemed to be enhanced at 60 oC. Cycling at a higher temperature generally lead to bigger capacities of the tin(IV) oxide electrodes.

     

     

    1. Courtney, I.A. and Dahn, J.R., J. Electrochem. Soc., 1997, 144, 2045-2052.
    2. Courtney, I.A.; McKinnon, W.R. and Dahn, J.R., J. Electrochem. Soc., 1999, 146, 59-68.
    3. Chouvin, J.; Branci, C.; Sarradin, J.; Olivier-Fourcade, J.; Jumas, J.C.; Simon, B. and Biensan, P., J. Power Sources, 1999, 81-82, 277-281.
    4. Chouvin, J.; Olivier-Fourcade, J.; Jumas, J.C.; Simon, B.; Biensan, P.; Fernández Madrigal, F.J.; Tirado, J.L. and Pérez Vicente, C., J. Electroanal. Chem., 2000, 494, 136-146.
    5. Sun, X.; Liu, J. and Li, Y., Chem. Mater., 2006, 18, 3486-3494.

     

  • 29.
    Böhme, Solveig
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Electrochemical behaviour of tin(IV) oxide electrodes in lithium-ion batteries at high potentials2015Conference paper (Other academic)
    Abstract [en]

    In commercial lithium-ion batteries graphite is currently the most common anode material. However, graphite has a rather limited volumetric and gravimetric capacity which is a drawback when higher energy densities are required, for instance, in cars. Here, other materials with higher capacities and energy densities like the alloying materials tin and silicon are, hence, required. Even bigger capacities could be obtained using tin oxide based compounds due to a combination of the tin oxide conversion reaction converting lithium to tin and lithium oxide and the alloying reaction between tin and lithium. However, tin oxides usually suffer a great capacity loss after the first cycle due to the irreversibility of the tin oxide reduction. [1,2] Nevertheless, there have been some reports suggesting a limited reversibility of the tin(IV) oxide conversion. [3-6]

    In this work we have investigated the voltammetric behaviour of tin(IV) oxide electrodes within different potential windows in order to study the influence of the alloying reaction on the conversion reaction (excluding the alloying reaction by cycling to 0.9 V vs. Li+/Li). In addition, rather high voltages (up to 3.7 V vs. Li+/Li) were applied to check the tin(IV) oxide conversion reversibility as well as electrode and electrolyte stability under these conditions. The results were also compared with those presented in an earlier model study carried with our group. [6]  Cycling experiments were likewise carried out at 60oC and these results will be compared to those obtained for cycling at room temperature. The products formed at different potentials and temperatures were investigated using XPS and SEM. The results confirmed the presence of a partial reversibility of the tin(IV) oxide conversion reaction which was enhanced at 60oC. It will be demonstrated that cycling at a higher temperature lead to larger capacities of tin(IV) oxide electrodes. In addition, the influence of different cycling rates on the capacity will be discussed.

     

    1. Courtney, I.A. and Dahn, J.R., J. Electrochem. Soc., 1997, 144, 2045-2052.
    2. Courtney, I.A.; McKinnon, W.R. and Dahn, J.R., J. Electrochem. Soc., 1999, 146, 59-68.
    3. Chouvin, J.; Branci, C.; Sarradin, J.; Olivier-Fourcade, J.; Jumas, J.C.; Simon, B. and Biensan, P., J. Power Sources, 1999, 81-82, 277-281.
    4. Chouvin, J.; Olivier-Fourcade, J.; Jumas, J.C.; Simon, B.; Biensan, P.; Fernández Madrigal, F.J.; Tirado, J.L. and Pérez Vicente, C., J. Electroanal. Chem., 2000, 494, 136-146.
    5. Sun, X.; Liu, J. and Li, Y., Chem. Mater., 2006, 18, 3486-3494
    6. Böhme, S.; Edström, K. and Nyholm, L., On the electrochemistry of tin oxide coated tin electrodes in lithium-ion batteries, Electrochim. Acta, 2015 (in press).

     

  • 30.
    Böhme, Solveig
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Electrochemical behaviour of tin(IV) oxide electrodes in lithium-ion batteries at high temperature and potentials2016Conference paper (Other academic)
    Abstract [en]

    In commercial lithium-ion batteries graphite is currently the most common anode material. However, graphite has a rather limited volumetric and gravimetric capacity which is a drawback when higher energy densities are required, for instance, in cars. Here, other materials with higher capacities and energy densities like the alloying materials tin and silicon are, hence, required. Even bigger capacities could be obtained using tin oxide based compounds due to a combination of the tin oxide conversion reaction converting lithium to tin and lithium oxide and the alloying reaction between tin and lithium. However, tin oxides usually suffer a great capacity loss after the first cycle due to the irreversibility of the tin oxide reduction.[1,2] Nevertheless, there have been some reports suggesting a limited reversibility of the tin oxide conversion. [3-6]

     

    In our work we have investigated the kinetic behaviour of different tin(IV) oxide based electrodes during electrochemical cycling in lithium-ion batteries for both the conversion and the alloying reaction. To be able to study the influence of the alloying reaction on the conversion reaction cycling was carried out within different potential windows (excluding the alloying reaction by cycling only to 0.9 V vs. Li+/Li). In addition, rather high voltages (up to 3.7 V vs. Li+/Li) were applied to check the tin(IV) oxide conversion reversibility as well as electrode and electrolyte stability under these conditions. The results were also compared with those presented in an earlier model study carried with our group. [6] Cycling experiments were likewise carried out at 60 oC as well as different scan rates and with different particle sizes and additives (i.e. aluminium oxide and diamond). The products formed at different potentials and temperatures for tin(IV) oxide electrodes were also investigated using XPS and SEM.

     

    The results confirmed the presence of a partial reversibility of the tin(IV) oxide conversion reaction which was enhanced at 60 oC. The study, thus, indicated that there is a kinetic limitation regarding the reoxidation of tin to tin oxide upon charge which can be overcome more easily when using higher temperatures or smaller particles. It will be demonstrated that cycling at a higher temperature, lower scan rate or with a smaller particle size leads to larger capacities of tin(IV) oxide electrodes. In addition, the influence of different additives on the capacity will be discussed.

                                                                                                                

    REFERENCES

    1. Courtney, I.A. and Dahn, J.R., J. Electrochem. Soc., 1997, 144, 2045-2052.
    2. Courtney, I.A.; McKinnon, W.R. and Dahn, J.R., J. Electrochem. Soc., 1999, 146, 59-68.
    3. Chouvin, J.; Branci, C.; Sarradin, J.; Olivier-Fourcade, J.; Jumas, J.C.; Simon, B. and Biensan, P., J. Power Sources, 1999, 81-82, 277-281.
    4. Chouvin, J.; Olivier-Fourcade, J.; Jumas, J.C.; Simon, B.; Biensan, P.; Fernández Madrigal, F.J.; Tirado, J.L. and Pérez Vicente, C., J. Electroanal. Chem., 2000, 494, 136-146.
    5. Sun, X.; Liu, J. and Li, Y., Chem. Mater., 2006, 18, 3486-3494
    6. Böhme, S.; Edström, K. and Nyholm, L., On the electrochemistry of tin oxide coated tin electrodes in lithium-ion batteries, Electrochim. Acta, 2015, 179, 482-494.
  • 31.
    Böhme, Solveig
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    On the electrochemistry of tin oxide coated tin electrodes in lithium-ion batteries2015In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 179, p. 482-494Article in journal (Refereed)
    Abstract [en]

    As tin based electrodes are of significant interest in the development of improved lithium-ion batteries it is important to understand the associated electrochemical reactions. In this work it is shown that the electrochemical behavior of SnO2 coated tin electrodes can be described based on the SnO2 and SnO conversion reactions, the lithium tin alloy formation and the oxidation of tin generating SnF2. The CV, XPS and SEM data, obtained for electrodeposited tin crystals on gold substrates, demonstrates that the capacity loss often observed for SnO2 is caused by the reformed SnO2 layer serving as a passivating layer protecting the remaining tin. Capacities corresponding up to about 80 % of the initial SnO2 capacity could, however, be obtained by cycling to 3.5 V vs. Li+/Li. It is also shown that the oxidation of the lithium tin alloy is hindered by the rate of the diffusion of lithium through a layer of tin with increasing thickness and that the irreversible oxidation of tin to SnF2 at potentials larger than 2.8 V vs. Li+/Li is due to the fact that SnF2 is formed below the SnO2 layer. This improved electrochemical understanding of the SnO2/Sn system should be valuable in the development of tin based electrodes for lithium-ion batteries.

  • 32.
    Böhme, Solveig
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Overlapping and rate controlling electrochemical reactions for tin(IV) oxide electrodes in lithiu-ion batteries2017In: Journal of Electroanalytical Chemistry, ISSN 0022-0728, E-ISSN 1873-2569, Vol. 797, p. 47-60Article in journal (Refereed)
    Abstract [en]

    The results of this extensive electrochemical study of the electrochemical reactions of SnO2 electrodes in lithium-ion batteries demonstrate that the different reduction and oxidation reactions overlap significantly during the cycling and that the rates of the redox reactions are limited by the mass transport through the layers of oxidation or reduction products formed on the electrodes. The experiments, which were carried out in the absence and presence of the lithium alloy reactions, show that the capacity losses seen on the first cycles mainly can be explained by an incomplete oxidation of the lithium tin alloy and an incomplete reformation of SnO2. The latter can be explained by the formation of thin tin oxide layers (i.e., SnO and SnO2), protecting the remaining tin, as the oxidation current then becomes limited by the Li+ diffusion rate though these layers. The results, also show that the first cycle SnO2 reduction was incomplete for the about 20 μm thick electrodes containing 1 to 6 μm large SnO2 particles. This can be ascribed to the formation of a layer of tin and Li2O (protecting the remaining SnO2) during the reduction process. Although the regeneration of the SnO2 always was slower than the reduction of the SnO2, the results clearly show that the SnO2 conversion reaction is far from irreversible, particularly at low scan rates and increased temperatures. Electrochemical cycling at 60 °C hence gave rise to increased capacities, but also a faster capacity loss, compared to at room temperature. These new findings indicate that a full utilization of SnO2 based electrodes at a given cycling rate only can be reached with sufficiently small particles since the allowed particle size is given by the time available for the mass transport through the formed surface layers. The present results consequently provide important insights into the phenomena limiting the use of SnO2 electrodes in lithium-ion batteries.

  • 33.
    Böhme, Solveig
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Overlapping and Rate Controlling Electrochemical Reactions for Tin(IV) Oxide Electrodes in Lithium-Ion BatteriesIn: Article in journal (Other academic)
  • 34.
    Böhme, Solveig
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Tai, Cheuk-Wai
    Stockholms Universitet.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Seisenbaeva, Gulaim A.
    Sveriges Lantbruksuniversitet.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Effects of Elevated Temperature and Vinylene Carbonate Additive on the Electrochemical Performance of SnO2 Nanoparticles in Lithium-Ion BatteriesManuscript (preprint) (Other academic)
  • 35.
    Carlsson, Daniel O
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Ferraz, Natalia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Fellström, Bengt
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Renal Medicine.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Mihranyan, Albert
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Strømme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Towards blood purification applications of polypyrrole and cellulose nanocomposites2013Conference paper (Refereed)
  • 36.
    Carlsson, Daniel O
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Ferraz, Natalia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Hong, Jaan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Clinical Immunology.
    Larsson, Rolf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Clinical Immunology.
    Fellström, Bengt
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Forensic Medicine.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Strømme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Mihranyan, Albert
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Conducting Nanocellulose Polypyrrole Membranes Intended for Hemodialysis2012In: European Cells and Materials, ISSN 1473-2262, E-ISSN 1473-2262, Vol. 23, no Suppl 5, p. 32-32Article in journal (Refereed)
  • 37.
    Carlsson, Daniel O
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Ferraz, Natalie
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Hong, J
    Larsson, R
    Fellström, Bengt
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Renal Medicine.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Mihranyan, Albert
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Conduting nanocellulose polypyrrole membranes intended for hemodialysis2012Conference paper (Refereed)
  • 38.
    Carlsson, Daniel O.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Lindh, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Mihranyan, Albert
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Cooxidant-free TEMPO-mediated oxidation of highly crystalline nanocellulose in water2014In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 4, no 94, p. 52289-52298Article in journal (Refereed)
    Abstract [en]

    Selective oxidation of C6 hydroxyls to carboxyls through 2,2,6,6,-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation, where the oxidizing species (TEMPO+) is generated by cooxidants, such as NaBrO, NaClO or NaClO2, has become a popular way to modify the surfaces of nanocellulose fibrils in aqueous solutions. Employing highly crystalline nanocellulose from Cladophora sp. algae we demonstrate that the same degree of oxidation (D.O.) can be achieved within approximately the same time by replacing the cooxidants with electrogeneration of TEMPO+ in a bulk electrolysis setup. The D.O. is controlled by the oxidation time and the maximum D.O. achieved (D.O. 9.8%, 0.60 mmol g-1 of carboxylic acids and 0 mmol g-1 aldehydes) corresponds to complete oxidation of the surface-confined C6. This shows that TEMPO+ is not sterically hindered from completely oxidizing the fibril surface of Cladophora nanocellulose, in contrast to earlier hypotheses that were based on results with wood-derived nanocellulose. The oxidation does not significantly affect the morphology, the specific surface area (>115 m2 g-1) or the pore characteristics of the water-insoluble fibrous particles that were obtained after drying, but depolymerization corresponding to [similar]20% was observed. For extensive oxidation times, the product recovery of water-insoluble fibrils decreased significantly while significant amounts of charge passed through the system. This could indicate that the oxidation proceeds beyond the fibril surface, in contrast to the current view that TEMPO-mediated oxidation is confined only to the surface.

  • 39.
    Carlsson, Daniel O
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Lindh, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Strømme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Mihranyan, Albert
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Cooxidant-free TEMPO-mediated oxidation of highly crystalline Cladophora nanocellulose2015Conference paper (Refereed)
  • 40.
    Carlsson, Daniel O
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Lindh, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Strømme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Mihranyan, Albert
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Electrochemical TEMPO-mediated Oxidation of Highly Crystalline Nanocellulose in Water2014In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 4, p. 52289-52298Article in journal (Refereed)
  • 41.
    Carlsson, Daniel O.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Mihranyan, Albert
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Tailoring porosities and electrochemical properties of composites composed of microfibrillated cellulose and polypyrrole2014In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 4, no 17, p. 8489-8497Article in journal (Refereed)
    Abstract [en]

    Composites of polypyrrole and nanocellulose (PPy/nanocellulose) have a high potential as electrodes in energy-storage devices and as membranes for electrochemically controlled ion-exchange systems. In the present work, it is demonstrated that such composites with 42-72% porosity can be produced by using microfibrillated cellulose (MFC) prepared through enzymatic pretreatment or carboxymethylation, or by using different amounts of MFC in the composite synthesis. Together with previous work, this shows that the porosity of PPy/nanocellulose composites can be tailored from 30 to 98% with increments of similar to 10%. Employing the full porosity range of the composites, it is demonstrated that the electrochemical oxidation rate of the materials depends on their porosity due to limitations in the counter ion diffusion process. By tailoring the porosities of PPy/nanocellulose composites, the electrochemical properties can consequently be controlled. The latter provides new possibilities for the manufacturing of electrochemically controlled ion-extraction and energy storage devices with optimized volumetric energy and power densities.

  • 42.
    Carlsson, Daniel O
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Nyström, Gustav
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Ferraz, Natalia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Mihranyan, Albert
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Strømme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Development of nanocellulose/polypyrrole composites towards blood purification2012In: Procedia Engineering, ISSN 1877-7058, E-ISSN 1877-7058, Vol. 44, p. 733-736Article in journal (Refereed)
  • 43.
    Carlsson, Daniel O
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Nyström, Gustav
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Ferraz, Natalia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Shou, Qi
    Berglund, Lars A
    Fellström, Bengt
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Mihranyan, Albert
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Strømme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Development of Nanocellulose/Polypyrrole Composites Towards Blood Purification2012In: Euromembrane 2012, Queen Elizabeth II Conference Centre, London, UK, 23-27 September 2012, 2012Conference paper (Refereed)
  • 44.
    Carlsson, Daniel O
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Nyström, Gustav
    KTH, Wallenberg Wood Science Center, Stockholm.
    Zhou, Qi
    KTH, Dept of Fibre & Polymer Technology, Stockholm.
    Berglund, Lars A.
    KTH, Dept of Fibre & Polymer Technology, Stockholm.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Electroactive nanofibrillated cellulose aerogel composites with tunable structural and electrochemical properties2012In: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 22, no 36, p. 19014-19024Article in journal (Refereed)
  • 45.
    Carlsson, Daniel O.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Sjödin, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    A Comparative Study of the Effects of Rinsing and Aging of Polypyrrole/Nanocellulose Composites on Their Electrochemical Properties2013In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 117, no 14, p. 3900-3910Article in journal (Refereed)
    Abstract [en]

    The effects of polymerization conditions, rinsing, and storage on composites composed of polypyrrole (PPy) and Cladophora nanocellulose in terms of purity, chemical composition, conductivity, and electroactivity were investigated using conductivity measurements, cyclic voltammetry, FTIR-ATR, XPS, and ICP-AES. A clear correlation between rinsing volume and PPy degradation was found using water- or NaCl-rinsing solutions as evidenced by conductivity and electroactivity losses. It was further found, through FTIR-ATR as well as XPS-measurements, that this degradation was caused by incorporation of hydroxyl groups in the PPy-layer. The extent of degradation correlated with a shift in the FTIR-ATR peak around 1300 cm(-1), showing that FTIR-ATR may be used as a quick diagnostic tool to evaluate the extent of degradation. By the use of acidic rinsing solution, this degradation effect was eliminated and resulted in superior samples in terms of both conductivity and electroactivity and also in a more efficient removal of reactants. Upon ambient storage, over a period of 200 days, a gradual decrease in conductivity was found for initially highly conductive samples. The electroactivity, on the other hand, was relatively unaffected by storage, showing that conductivity measurements alone are ineffective to determine the degree of polymer degradation if the water content is not controlled. Also, FTIR-ATR measurements indicated that the oxidation state did not change to any large extent upon storage and that only minor degradation of PPy occurred. The results presented herein thus offer valuable guidelines on how to develop simple and reliable postsynthesis treatments of conducting polymer paper composites with performance fulfilling requirements on stability, electroactivity, and purity in applications such as environmentally friendly energy storage devices and biomedical applications.

  • 46.
    Caron, L.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Hudl, M.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Höglin, Viktor
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Dung, N. H.
    Gómez, Cesar Pay
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Bruck, E.
    Andersson, Yvonne
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Nordblad, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Magnetocrystalline anisotropy and the magnetocaloric effect in Fe2P2013In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 88, no 9, p. 094440-Article in journal (Refereed)
    Abstract [en]

    Magnetic and magnetocaloric properties of high-purity, giant magnetocaloric polycrystalline and single-crystalline Fe2P are investigated. Fe2P displays a moderate magnetic entropy change, which spans over 70 K and the presence of strong magnetization anisotropy proves this system is not fully itinerant but displays a mix of itinerant and localized magnetism. The properties of pure Fe2P are compared to those of giant magnetocaloric (Fe,Mn)2(P,A) (where A = As, Ge, Si) compounds helping understand the exceptional characteristics shown by the latter, which are so promising for heat pump and energy conversion applications.

  • 47.
    Cedervall, Johan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Andersson, Mikael Svante
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Sarkar, Tapati
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Delczeg-Czirjak, Erna K.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Bergqvist, Lars
    Hansen, Thomas C.
    Beran, Premysl
    Nordblad, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Magnetic structure of the magnetocaloric compound AlFe2B22016In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 654, p. 784-791Article in journal (Refereed)
    Abstract [en]

    The crystal and magnetic structures of AlFe2B2 have been studied with a combination of X-ray and neutron diffraction and electronic structure calculations. The magnetic and magnetocaloric properties have been investigated by magnetisation measurements. The samples have been produced using high temperature synthesis and subsequent heat treatments. The compound crystallises in the orthorhombic crystal system Cmmm and it orders ferromagnetically at 285 K through a second order phase transition. At temperatures below the magnetic transition the magnetic moments align along the crystallographic a-axis. The magnetic entropy change from 0 to 800 kA/m was found to be - 1.3 J/K kg at the magnetic transition temperature.

  • 48.
    Cedervall, Johan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Beran, Premysl
    ASCR, Inst Nucl Phys, Hlavni 130, Rez 25068, Czech Republic.
    Vennström, Marie
    AB Sandvik Mat Technol, SE-81181 Sandviken, Sweden.
    Danielsson, Therese
    Etteplan Sweden AB, SE-17154 Solna, Sweden.
    Ronneteg, Sabina
    AB Sandvik Mat Technol, SE-81181 Sandviken, Sweden.
    Höglin, Viktor
    Scienta Sauna Syst AB, SE-75228 Uppsala, Sweden.
    Lindell, David
    Swerea KIMAB AB, Box 7047, SE-16407 Kista, Sweden.
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    André, Gilles
    CEA Saclay, LLB, F-91191 Gif Sur Yvette, France.
    Andersson, Yvonne
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Nordblad, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Low temperature magneto-structural transitions in Mn3Ni20P62016In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 237, p. 343-348Article in journal (Refereed)
    Abstract [en]

    Abstract X-ray and neutron powder diffraction has been used to determine the crystal and magnetic structure of Mn3Ni20P6. The crystal structure can be described as cubic with space group Fm 3 ¯ m (225) without any nuclear phase transformation within studied temperature interval from room temperature down to 4 K. The magnetic structure of Mn3Ni20P6 is complex with two independent magnetic positions for the Mn atoms and the compound passes three successive magnetic phase transitions during cooling. At 30 K the spins of the Mn atoms on the Wyckoff 4a site (Mn1) order to form a primitive cubic antiferromagnetic structure with propagation vector k=(0 0 1). Between 29 and 26 K the Mn atoms on the Wyckoff 8c site (Mn2) order independently on already ordered Mn1 magnetic structure forming a commensurate antiferromagnetic structure with propagation vector k=(0 0 ½) and below 26 K, both Mn positions order to form an incommensurate helical structure with propagation vector k=(0 0 ~0.45). Magnetization vs. temperature curve of Mn3Ni20P6 shows a steep increase indicating some magnetic ordering below 230 K and a sharp field dependent anomaly in a narrow temperature range around 30 K.

  • 49.
    Cedervall, Johan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Häggström, Lennart
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Ericsson, Tore
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Mössbauer study of the magnetocaloric compound AlFe2B22016In: Hyperfine Interactions, ISSN 0304-3843, E-ISSN 1572-9540, Vol. 237, article id 47Article in journal (Refereed)
    Abstract [en]

    Mössbauer spectroscopy in the ferromagnetic AlFe2B2 reveals Tc=299 K and shows good agreement with magnetic measurements. The crystals are plate-shaped. The flakes are found from X-ray diffraction to be in the crystallographic ac-plane in the orthorhombic system. The axes of the principle electric field gradient tensor are, by symmetry, colinear with the crystal a-, b- and c-axes. By using information about the quadrupole splitting and line asymmetry in the paramagnetic regime together with the quadrupole shift of the resonance lines in the ferromagnetic regime the magnetic hyperfine field direction is found to be in the ab-plane having an angle =40° to the b-axis.

  • 50.
    Cedervall, Johan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Kontos, Sofia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Hansen, Thomas C.
    Balmes, Olivier
    Martinez-Casado, Francisco Javier
    Matej, Zdenek
    Beran, Premysl
    Svedlindh, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Gunnarsson, Klas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Magnetostructural transition in Fe5SiB2 observed with neutron diffraction2016In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 235, p. 113-118Article in journal (Refereed)
    Abstract [en]

    The crystal and magnetic structure of Fe5SiB2 has been studied by a combination of X-ray and neutron diffraction. Also, the magnetocrystalline anisotropy energy constant has been estimated from magnetisation measurements. High quality samples have been prepared using high temperature synthesis and subsequent heat treatment protocols. The crystal structure is tetragonal within the space group I4/mcm and the compound behaves ferromagnetically with a Curie temperature of 760 K. At 172 K a spin reorientation occurs in the compound and the magnetic moments go from aligning along the c-axis (high T) down to the ab-plane (low T). The magnetocrystalline anisotropy energy constant has been estimated to 03 MJ/m(3) at 300 K.

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