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  • 1. Biendicho, J. J.
    et al.
    Shafeie, S.
    Frenck, L.
    Gavrilova, D.
    Boehme, S.
    Bettanini, A. M.
    Svedlindh, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Hull, S.
    Zhao, Z.
    Istomin, S. Ya.
    Grins, J.
    Svensson, G.
    Synthesis and characterization of perovskite-type Sr(x)Y1-xFeO(3-delta) (0.63 <= x < 1.0) and Sr0.75Y0.25Fe1-yMyO3-delta (M=Cr, Mn, Ni), (y=0.2, 0.33, 0.5)2013In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 200, p. 30-38Article in journal (Refereed)
    Abstract [en]

    Oxygen-deficient ferrates with the cubic perovskite structure SrxY1-xFeO3-delta were prepared in air (0.71 <= x <= 0.91) as well as in N-2 (x=0.75 and 0.79) at 1573 K. The oxygen content of the compounds prepared in air increases with increasing strontium content from 3-delta=2.79(2) for x=0.75 to 3-delta=2.83(2) for x=0.91. Refinement of the crystal structure of Sr0.25Y0.25FeO2.29 using TOP neutron powder diffraction (NPD) data shows high anisotropic atomic displacement parameter (ADP) for the oxygen atom resulting from a substantial cation and anion disorder. Electron diffraction (ED) and highresolution electron microscopy (HREM) studies of Sr0.75Y0.25FeO2.79 reveal a modulation along (1 0 0)(p) with G +/- similar to 0.4(1 0 0)(p) indicating a local ordering of oxygen vacancies. Magnetic susceptibility measurements at 5-390 K show spin-glass behaviour with dominating antiferromagnetic coupling between the magnetic moments of Fe cations. Among the studied compositions, Sr0.75Y0.25Fe02.79 shows the lowest thermal expansion coefficient (TEC) of 10.5 ppm/K in air at 298-673 K. At 773-1173 K TEC increases up to 17.2 ppm/K due to substantial reduction of oxygen content. The latter also results in a dramatic decrease of the electrical conductivity in air above 673 K. Partial substitution of Fe by Cr, Mn and Ni according to the formula Sr0.75Y0.25Fe1-yMyO3-delta (y=0.2, 0.33, 0.5) leads to cubic perovskites for all substituents with y=0.2. Their TECs are higher in comparison with un-doped Sr0.75Y0.25Fe02.79. Only M=Ni has increased electrical conductivity compared to un-doped Sr0.75Y0.25Fe02.79. 

  • 2. Brant, William R.
    et al.
    Schmid, Siegbert
    Gu, Qinfen
    Withers, Ray L.
    Hester, James
    Avdeev, Maxim
    Temperature and composition dependent structural investigation of the defect perovskite series Sr1−xTi1−2xNb2xO3, 0≤x≤0.22010In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 183, no 9, p. 1998-2003Article in journal (Refereed)
  • 3.
    Carvalho, Paulo H. B. Brant
    et al.
    Stockholm Univ, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden.
    Mace, Amber
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Andersson, Ove
    Umea Univ, Dept Phys, SE-90187 Umea, Sweden.
    Tulk, Chris A.
    Oak Ridge Natl Lab, Chem & Engn Mat Div, Oak Ridge, TN 37831 USA.
    Molaison, Jamie
    Oak Ridge Natl Lab, Chem & Engn Mat Div, Oak Ridge, TN 37831 USA.
    Häussermann, Ulrich
    Stockholm Univ, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden.
    Elucidating the guest disorder in structure II argon hydrate - A neutron diffraction isotopic substitution study2020In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 285, article id 121220Article in journal (Refereed)
    Abstract [en]

    Clathrate hydrates with the cubic structure II (CS-II) form typically with large guest molecules, such as tetrahydrofuran, trimethylamine oxide, or propane. However, CS-II is also realized for argon hydrate despite the comparatively small van der Waals diameter of the guest (around 3.8 angstrom). Here, the structure of deuterated argon hydrate was studied at ambient pressure in the temperature range 20-95 K using neutron diffraction and comparing natural Ar with Ar-36, which scatters neutrons more than 13 times more efficiently. The procedure allowed to unambiguously establish the positional disorder within the large cages of CS-H, while simultaneously refining host and guest structures. These cages are singly occupied and off-centered argon atoms distribute on two tetrahedron-shaped split positions with a ratio 3:1. Molecular dynamics (MD) simulations revealed that the crystallographic positional disorder structure is due to mobile argon atoms even at 20 K. The MD potential energy distribution confirmed the diffraction model. It is noted that the unit cell volumes of argon hydrate in the investigated temperature range are virtually identical to N-2 hydrate, which has a similar composition at ambient pressure, indicating a very similar (slightly attractive) host-guest interaction.

  • 4.
    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.

  • 5.
    Cedervall, Johan
    et al.
    Stockholm Univ, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden.;Rutherford Appleton Lab, ISIS Pulsed Neutron & Muon Facil, Harwell Campus, Didcot OX11 0QX, Oxon, England..
    Clulow, Rebecca
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Boström, Hanna
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Max Planck Inst Solid State Res, Heisenbergsstr 1, D-70569 Stuttgart, Germany..
    Joshi, Deep C.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Andersson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics. Chalmers Univ Technol, Dept Chem & Chem Engn, S-41296 Gothenburg, Sweden..
    Mathieu, Roland
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Beran, Premysl
    Acad Sci Czech Republ, Nucl Phys Inst, Rez 25068, Czech Republic.;European Spallat Source ESS ERIC, Box 176, S-22100 Lund, Sweden..
    Smith, Ronald, I
    Rutherford Appleton Lab, ISIS Pulsed Neutron & Muon Facil, Harwell Campus, Didcot OX11 0QX, Oxon, England..
    Tseng, Jo-Chi
    Deutsch Elektronen Synchrotron DESY, Notkestr 85, D-22607 Hamburg, Germany..
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Berastegui, Pedro
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Shafeie, Samrand
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Chalmers Univ Technol, Dept Phys, S-41296 Gothenburg, Sweden..
    Phase stability and structural transitions in compositionally complex LnMO(3) perovskites2021In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 300, article id 122213Article in journal (Refereed)
    Abstract [en]

    Entropy stabilised materials have possibilities for tailoring functionalities to overcome challenges in materials science. The concept of configurational entropy can also be applied to metal oxides, but it is unclear whether these could be considered as solid solutions in the case of perovskite-structured oxides and if the configurational entropy plays a stabilising role. In this study, compositionally complex perovskite oxides, LnMO(3) (Ln = La, Nd, Sm, Ca and Sr, M = Ti, Cr, Mn, Fe, Co, Ni, and Cu), are investigated for their phase stability and magnetic behaviour. Phase-pure samples were synthesised, and the room temperature structures were found to crystallise in either Pnma or R (3) over barc space groups, depending on the composition and the resulting tolerance factor, while the structural transition temperatures correlate with the pseudo cubic unit cell volume. The techniques used included diffraction with X-rays and neutrons, both ex- and in-situ, X-ray photoelectron spectroscopy, magnetometry as well as electron microscopy. Neutron diffraction studies on one sample reveal that no oxygen vacancies are found in the structure and that the magnetic properties are ferrimagnetic-like with magnetic moments mainly coupled antiferromagnetically along the crystallographic c-direction. X-ray photoelectron spectroscopy gave indications of the oxidation states of the constituting ions where several mixed oxidation states are observed in these valence-compensated perovskites.

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  • 6.
    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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  • 7.
    Clulow, Rebecca
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Hedlund, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Vishina, Alena
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Svedlindh, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Magnetic and Structural Properties of the Fe5Si1-xGexB2 System2022In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 316, article id 123576Article in journal (Refereed)
    Abstract [en]

    A series of compounds with compositions Fe5Si1-xGexB2 were synthesised and their structural and magnetic properties were investigated. The Mo5SiB2-type structure with tetragonal I4/mcm space group is maintained for all compounds with x < 0.15, which is estimated as the compositional limit of the system. The unit cell pa-rameters expand with Ge content before reaching a plateau of a = 5.5581(1) and c = 10.3545(1) angstrom at x = 0.15. The saturation magnetisation (MS) decreased slightly with increasing Ge content whilst the magnetocrystalline anisotropy energy (MAE) remains almost unaffected. The Curie temperature for all compounds studied is at 790 K whilst the spin-reorientation temperature shows suppression from 172 K to 101 K where x = 0.15. Ab Initio calculations reveal an increase in MAE for compositions up to x = 0.25 and a decreased magnitude of MAE of-0.14 MJ/m3 for the hypothetical compound Fe5GeB2 relative to the parent compound Fe5SiB2.

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  • 8. Denys, R. V.
    et al.
    Riabov, A. B.
    Yartys, V. A.
    Sato, Masashi
    Delaplane, R. G.
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, The Studsvik Neutron Research Laboratory.
    Mg substitution effect on the hydrogenation behaviour, thermodynamic and structural properties of the La2Ni7-H(D)(2) system2008In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 181, no 4, p. 812-821Article in journal (Refereed)
    Abstract [en]

    The present work is focused on studies of the influence of magnesium on the hydrogenation behaviour of the (La,Mg)(2)Ni-7 alloys. Substitution of La in La2Ni7 by Mg to form La1.5Mg0.5Ni7 preserves the initial Ce2Ni7 type of the hexagonal P6(3)/mmc structure and leads to contraction of the unit cell. The system La1.5Mg0.5Ni7-H2 (D-2) was studied using in situ synchrotron X-ray and neutron powder diffraction in H-2/D-2 gas and pressure-composition-temperature measurements. La replacement by Mg was found to proceed in an ordered way, only within the Laves-type parts of the hybrid crystal structure, yielding formation of LaMgNi4 slabs with statistic and equal occupation of one site by La and Mg atoms. Mg alters structural features of the hydrogenation process. Instead of a strong unilateral anisotropic expansion which takes place on hydrogenation of La2Ni7, the unit cell of La1.5Mg0.5Ni7D9.1 is formed by nearly equal hydrogen-induced expansions proceeding in the basal plane (Delta a/a = 7.37%) and along [001] (Delta c/c = 9.67%). In contrast with La2Ni7D6.5 where only LaNi2 layers absorb hydrogen atoms, in La1.5Mg0.5Ni7D9.1 both LaNi5 and LaMgNi4 layers become occupied. Nine types of sites were found to be filled by D in total, including tetrahedral (La,Mg)(2)Ni-2, (La,Mg)Ni-3, Ni-4, tetragonal pyramidal La2Ni3 and trigonal bipyramidal (La,Mg)(3)Ni-2 interstices. The hydrogen sublattice around the La/Mg site shows formation of two co-ordination spheres of D atoms: an octahedron MgD6 and a 16-vertex polyhedron LaD16 around La. The interatomic distances are in the following ranges: La-D (2.28-2.71), Mg-D (2.02-2.08), Ni-D (1.48-1.86 angstrom). All D-D distances exceed 1.9 angstrom. Thermodynamic PCT studies yielded the following values for the Delta H and Delta S of hydrogenation/decomposition; Delta H-H = -15.7 +/- 0.9 kJ (mol(H))(-1) and Delta S-H = -46.0 +/- 3.7 J (K mol(H))(-1) for H-2 absorption, and Delta H-H = 16.8 +/- 0.4 kJ (mol(H))(-1) and Delta S-H = 48.1 +/- 1.5 J (K mol(H))(-1) for H-2 desorption.

  • 9. Denys, R. V.
    et al.
    Yartys, V. A.
    Sato, Masashi
    Riabov, A. B.
    Delaplane, R. G.
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, The Studsvik Neutron Research Laboratory.
    Crystal chemistry and thermodynamic properties of anisotropic Ce2Ni7H4.7 hydride2007In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 180, no 9, p. 2566-2576Article in journal (Refereed)
    Abstract [en]

    A new intermetallic deuteride Ce2Ni7D4.7 with an anomalous volume expansion has been studied. Its structure was solved on the basis of in situ neutron diffraction data. Expansion proceeds along the c-axis and within the CeNi2 slabs only. All D atoms are located inside these slabs and on the border between CeNi2 and CeNi5. Ordering of D atoms in the bulk of CeNi2 is accompanied by substantial deformation of these slabs thus lowering the hexagonal symmetry to orthorhombic [space group Pmcn (No. 62); a = 4.9251(3) angstrom b = 8.4933(4) angstrom, c = 29.773(1) angstrom]. Inside the CeNi2 layer the hydrogen sublattice is completely ordered; all D-D distances exceed 2.0 angstrom Local coordination of Ni by D inside the CeNi, blocks is of "open", saddle-like type. Hydrogen ordering is mainly determined by Ce-H and H-H interactions. The press ure-composition-temperature measurements yielded the following thermodynamic parameters of the formation of the hydride: Delta H = -22.4 kJ/MOl(H), Delta S = -59.9 J/(K mol(H)).

  • 10.
    Ek, Gustav
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Nedumkandathil, Reji
    Stockholm Univ, Dept Mat & Environm Chem, Stockholm, Sweden.
    Johansson, Robert
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Montero, Jorge
    Univ Paris Est, Inst Chim & Mat Paris Est, CNRS, Champs Sur Marne, France.
    Zlotea, Claudia
    Univ Paris Est, Inst Chim & Mat Paris Est, CNRS, Champs Sur Marne, France.
    Andersson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics. Chalmers Univ Technol, Dept Chem & Chem Engn, Gothenburg, Sweden.
    Nordblad, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Tang, Chiu
    Diamond Light Source, Harwell Sci & Innovat Campus, Didcot, Oxon, England.
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Haussermann, Ulrich
    Stockholm Univ, Dept Mat & Environm Chem, Stockholm, Sweden.
    Hydrogen induced structure and property changes in Eu3Si42019In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 277, p. 37-45Article in journal (Refereed)
    Abstract [en]

    Hydrides Eu3Si4H2-X were obtained by exposing the Zintl phase Eu3Si4 to a hydrogen atmosphere at a pressure of 30 bar and temperatures from 25 to 300 degrees C. Structural analysis using powder X-ray diffraction (PXRD) data suggested that hydrogenations in a temperature range 25-200 degrees C afford a uniform hydride phase with an orthorhombic structure (Immm, a approximate to 4.40 angstrom, b approximate to 3.97 angstrom, c approximate to 19.8 angstrom), whereas at 300 degrees C mixtures of two orthorhombic phases with c approximate to 19.86 and approximate to 19.58 angstrom were obtained. The assignment of a composition Eu3Si4H2+x is based on first principles DFT calculations, which indicated a distinct crystallographic site for H in the Eu3Si4 structure. In this position, H atoms are coordinated in a tetrahedral fashion by Eu atoms. The resulting hydride Eu3Si4H2 is stable by -0.46 eV/H atom with respect to Eu3Si4 and gaseous H-2. Deviations between the lattice parameters of the DFT optimized Eu3Si4H2 structure and the ones extracted from PXRD patterns pointed to the presence of additional H in interstitials also involving Si atoms. Subsequent DFT modeling of compositions Eu3Si4H3 and Eu3Si4H4 showed considerably better agreement to the experimental unit cell volumes. It was then concluded that the hydrides of Eu3Si4 have a composition Eu3Si4H2+x (x < 2) and are disordered with respect to H in Si2Eu3 interstitials. Eu3Si4 is a ferromagnet with a Tc at about 120 K. Ferromagnetism is effectively quenched in Eu3Si4H2+x. The effective magnetic moment for both materials is 7.5 pg which is typical for compounds containing Eu2+ 4f(7) ions.

  • 11. Eriksson, Annika K.
    et al.
    Lindberg, Fredrik
    Svensson, Gunnar
    Svedlindh, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Henry, Paul F.
    Eriksson, Sten-G.
    Knee, Christopher S.
    Influence of iron addition on the oxygen-deficient Sr0.85Bi0.15Co1-xFexO3-delta (0.0 <= x <= 1.0) perovskites2008In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 181, no 8, p. 2031-2040Article in journal (Refereed)
    Abstract [en]

    A series of oxygen-deficient Sr0.85Bi0.15Co1-xFexO3-delta (0.0 <= x <= 1.0) perovskite phases were prepared using solid-state reaction. Results of neutron powder diffraction analyses show that the introduction of Fe onto the B-site severely effects the long range coherence of the oxygen vacancy ordered, 14/mmm supercell, observed for the x = 0.0 sample. For x = 0.1 a smaller, a = b approximate to a(p), c approximate to 2a(p), P4/mmm supercell gives the best agreement to the diffraction data, whilst phases in the range 0.2 <= x <= 0.6 adopt disordered cubic perovskite structures. Pseudo-cubic, a = b approximate to a(p), c approximate to a(p), structures are found for x >= 0.8. Evidence of weak superstructures, reflecting local oxygen ordering, is also obtained from electron diffraction. For all oxygen-annealed phases the average structure reverts to cubic Pm (3) over barm. The as-prepared samples show G-type antiferromagnetic order at room temperature. The oxygen annealed x = 0.10, 0.25 and 1.0 samples display low-temperature spin-glass transitions.

  • 12.
    Eriksson, Therese
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Bergqvist, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Theoretical Magnetism.
    Nordblad, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science.
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Theoretical Magnetism.
    Andersson, Yvonne
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Structural and magnetic characterization of Mn3IrGe and Mn3Ir(Si1-xGex): experiments and theory2004In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 177, no 11, p. 4058-4066Article in journal (Refereed)
    Abstract [en]

    The Structural and magnetic propertiesof a new ternary Ir-Mn-Ge phase, Mn3IrGe, as well as the solid solution Mn3Ir(Si1_xGex), O<x<1, have been investigated by means of X-ray and neutron powder diffraction, magnetization measurements and first principles calculations. The crystal structure is cubic, of the AlAu4-type (an ordered form of the ß-Mn structure), Z = 4. space group P213, and the unit-cell dimension varies linearly with the silicon content. For all compositions, antiferromagnetic

    ordering is found below a critical temperature of about 225 K. The magnetic structure is noncollinear, as a result of frustrated magnetic interactions on a triangular network of Mn atoms, on which the moments rotate 120° around the triangle axes. The magnitude of the magnetic moment at 10 K is 3.39(4) µB for Mn3IrGe. The theoretical calculations reproduce with very good accuracy the magnitudes as well as the directions of the experimentally observed magnetic moments.

  • 13.
    Fang, Hailiang
    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.
    Ångstrom, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Cedervall, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    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.
    Directly obtained tau-phase MnAl, a high performance magnetic material for permanent magnets2016In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 237, p. 300-306Article in journal (Refereed)
    Abstract [en]

    The metastable tetragonal iota-phase has been directly obtained from casting Mn0.54Al0.46 and (Mn0.55Al0.45)(100)C-2 using the drop synthesis method. The as-casted samples were ball milled to decrease the particle size and relaxed at 500 degrees C for 1 h. The phase composition, crystallographic parameters, magnetic properties and microstructure were systematically studied. The results reveal that the iota-phase could be directly obtained from drop synthesis. The highest M-s of 117 emu/g was achieved in the (Mn0.55Al0.45)(100)C-2 where the iota-phase was stabilized by doping with carbon. Carbon doping increased the c/a ratio of the tau-phase as it occupies specific interstitial positions (1/2, 1/2, 0) in the structure. Furthermore, ball milling increases the coercivity (H-c) at the expense of a decrease in magnetic saturation (M-s). The increase in coercivity is explained by a decrease of grain size in conjunction with domain wall pinning due to defects introduced during the ball milling process.

  • 14.
    Grau-Atienza, A.
    et al.
    Univ Alicante, Dept Inorgan Chem, Mol Nanotechnol Lab, Carretera San Vicente S-N, E-03690 Alicante, Spain..
    Serrano, E.
    Univ Alicante, Dept Inorgan Chem, Mol Nanotechnol Lab, Carretera San Vicente S-N, E-03690 Alicante, Spain..
    Linares, N.
    Univ Alicante, Dept Inorgan Chem, Mol Nanotechnol Lab, Carretera San Vicente S-N, E-03690 Alicante, Spain..
    Svedlindh, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Seisenbaeva, G.
    BioCtr SLU, Dept Chem & Biotechnol, Box 7015, SE-75007 Uppsala, Sweden..
    Garcia-Martinez, J.
    Univ Alicante, Dept Inorgan Chem, Mol Nanotechnol Lab, Carretera San Vicente S-N, E-03690 Alicante, Spain..
    Magnetically separable mesoporous Fe3O4/silica catalysts with very low Fe3O4 content2016In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 237, p. 138-143Article in journal (Refereed)
    Abstract [en]

    Two magnetically separable Fe3O4/SiO2 (aerogel and MSU-X) composites with very low Fe3O4 content (< 1 wt%) have been successfully prepared at room temperature by co-condensation of MPTES-functionalized Fe3O4 nanoparticles (NPs) with a silicon alkoxide. This procedure yields a homogeneous incorporation of the Fe3O4 NPs on silica supports, leading to magnetic composites that can be easily recovered using an external magnetic field, despite their very low Fe3O4 NPs content (ca. 1 wt%). These novel hybrid Fe3O4/SiO2 materials have been tested for the oxidation reaction of 3,3',5,5'-tetramethylbenzidine (TMB) with hydrogen peroxide showing an enhancement of the stability of the NPs in the Fe3O4/silica aerogel as compared to the Fe3O4 NPs alone, even after five catalytic cycles, no leaching or agglomeration of the Fe3O4/SiO2 systems. 

  • 15.
    Höglin, Viktor
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Hudl, Matthias
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics. ICT Materials Physics, KTH Royal Institute of Technology.
    Caron, Luana
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics. Fundamental Aspects of Materials and Energy, Faculty of Applied Sciences, TUDelft.
    Beran, Premysl
    Nuclear Physics Institute, Academy of Sciences of the Czech Republic.
    Sørby, Magnus H.
    Physics Department, Institute for Energy Technology.
    Nordblad, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Andersson, Yvonne
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Detailed study of the magnetic ordering in FeMnP0.75Si0.252015In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 221, p. 240-246Article in journal (Refereed)
    Abstract [en]

    Magnetic and crystallographic properties of FeMnP0.75Si0.25 in the hexagonal Fe2P-type structure have been investigated by X-ray powder diffraction, neutron powder diffraction and magnetic measurements. The room temperature diffractograms reveal co-existence of two distinct structural phases in the samples with small, but significant, differences only in the unit cell dimensions. The volume ratio between the two phases is governed by the annealing conditions. One of the phases orders ferromagnetically (TC = 250 K) and the other in an incommensurate antiferromagnetic structure at low temperatures (qx = 0.363(1), TN = 150 K).

  • 16.
    Höglin, Viktor
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Hudl, Matthias
    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 Materials Chemistry, Inorganic Chemistry.
    Nordblad, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Beran, Premysl
    Nuclear Physics Institute, Academy of Sciences of the Czech Republic.
    Andersson, Yvonne
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    The crystal and magnetic structure of the magnetocaloric compound FeMnP0.5Si0.52011In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 184, no 9, p. 2434-2438Article in journal (Refereed)
    Abstract [en]

    The crystal and magnetic structure of the magnetocaloric compound FeMnP0.5Si0.5 has been studied by means of neutron and X-ray powder diffraction. Single phase samples of nominal composition FeMnP0.5Si0.5 have been prepared by the drop synthesis method. The compound crystallizes in the Fe2P-type structure (P-62m) with the magnetic moments aligned along the a-axis. It is found that the Fe atoms are mainly situated in the tetrahedral 3g site while the Mn atoms prefer the pyramidal 3f position. The material is ferromagnetic (TC=382 K) and at 296 K the total magnetic moment is 4.4 µB/f.u. It is shown that the magnetic moment in the 3f site is larger (2.5 µB) than in the 3g site (1.9 µB).

  • 17. Ivanov, S.A.
    et al.
    Eriksson, S-G.
    Tellgren, Roland
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Structural Chemistry.
    Rundlöf, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Structural Chemistry.
    Nordblad, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Eriksen, Jytte
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, The Studsvik Neutron Research Laboratory.
    Ba3Fe2WO9-delta: Effect of oxygen non-stoichiometry on structural and magnetic properties2006In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 179, no 8, p. 2645-2655Article in journal (Refereed)
    Abstract [en]

    The magnetic and structural properties of oxygen-deficient perovskites with composition Ba3Fe2WO9-6 (BFWO) have been systematically studied for two different oxygen contents corresponding to delta = 0.00 and 0.55 in the chemical formula in order, to determine and correlate their chemical composition, structural and magnetic properties. The evolution of nuclear and magnetic structures with temperature has been investigated by neutron powder diffraction. It was shown that at room temperature the stoichiometric compound (delta = 0.00) adopts a hexagonal 6H-perovskite structure (space group P6(3)/mmc). This phase, when heated at high temperature under a stream of Ar gas, transforms to an oxygen-deficient phase delta = 0.55), which is an ordered cubic perovskite structure (space group Fm-3m). The crystallographic and magnetic properties of the obtained phases are compared, and it is clear that the magnetic properties are significantly affected by oxygen non-stoichiometry. These changes of magnetic properties for such a slight decrease in oxygen content are interpreted as a result of structural transformations. Together with the experimental results based on neutron powder diffraction data a discussion of some aspects of the structural transformation (P6(3)/mmc -> Fm-3m) is presented.

  • 18.
    Ivanov, Sergey A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics. Karpov Inst Phys Chem, Dept Inorgan Mat, Moscow 105064, Russia.
    Beran, P.
    CAS, Inst Nucl Phys, Hlavni 130, Rez 25068, Czech Republic..
    Bazuev, G.
    Russian Acad Sci, Inst Solid State Chem, Ural Branch, Ekaterinburg 620990, Russia..
    Tellgren, Roland
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Sarkar, Tapati
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Nordblad, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Mathieu, Roland
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Perovskite solid solutions La0.75Bi0.25Fe1-xCrxO3: Preparation, structural, and magnetic properties2017In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 254, p. 166-177Article in journal (Refereed)
    Abstract [en]

    Solid solutions of La0.75Bi0.25Fe1−xCrxO3 (x = 0.1, 0.25, 0.5, and 0.75) prepared by conventional solid state reaction have been studied by means of X-ray powder diffraction (XRPD), neutron powder diffraction (NPD) and magnetic measurements. The NPD and XRPD patterns indicate orthorhombic structure (space group Pnma) for all compositions in the whole temperature range investigated (4–900 K). The lattice parameters of La0.75Bi0.25Fe1−xCrxO3 were found to decrease with the Cr content. It was established that the Fe3+ and Cr3+ cations are randomly positioned at the B-site of the perovskite structure.

    All samples order antiferromagnetically below transition temperatures that decrease with increasing Cr content, from around 700 K for x = 0.1 to about 300 K for x = 0.75. The antiferromagnetic arrangement of the Fe3+/Cr3+ magnetic moments in the B-site is of G-type along the x-axis (Gx mode) with propagation vector k = (0,0,0) for all concentrations of Cr. Effects of the composition on several structural distortion parameters were investigated and an anomalous variation of the octahedral deformation with Cr content was found. Whilst the overall octahedral deformation varies irregularly with increasing Cr content, the octahedral tilting was found to decrease monotoneously.

  • 19.
    Khan, Arshad
    et al.
    Southeast Univ, Natl Demonstrat Ctr Expt Biomed Engn Educ, State Key Lab Bioelect, Nanjing, Jiangsu, Peoples R China.
    Liu, Mei
    Southeast Univ, Natl Demonstrat Ctr Expt Biomed Engn Educ, State Key Lab Bioelect, Nanjing, Jiangsu, Peoples R China.
    Usman, Rabia
    Southeast Univ, Natl Demonstrat Ctr Expt Biomed Engn Educ, State Key Lab Bioelect, Nanjing, Jiangsu, Peoples R China.
    He, Nongyue
    Southeast Univ, Natl Demonstrat Ctr Expt Biomed Engn Educ, State Key Lab Bioelect, Nanjing, Jiangsu, Peoples R China; Hunan Univ Technol, Hunan Key Lab Biomed Nanomat & Devices, Econ Forest Cultivat & Utilizat Collaborat Innova, Zhuzhou, Peoples R China.
    Li, Rongrong
    Taizhou Univ, Sch Pharmaceut Chem & Mat Engn, Taizhou, Zhejiang, Peoples R China.
    Sayed, Sayed Mir
    Southeast Univ, Natl Demonstrat Ctr Expt Biomed Engn Educ, State Key Lab Bioelect, Nanjing, Jiangsu, Peoples R China.
    Li, Shaohan
    Southeast Univ, Sch Mat Sci & Engn, Jiangsu Key Lab Adv Metall Mat, Nanjing, Jiangsu, Peoples R China.
    Sun, Weiwei
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. KTH Royal Inst Technol, Dept Mat Sci & Engn, Stockholm, Sweden.
    Chen, Hui
    Hunan Univ Technol, Hunan Key Lab Biomed Nanomat & Devices, Econ Forest Cultivat & Utilizat Collaborat Innova, Zhuzhou, Peoples R China.
    Zhang, Lubing
    Taizhou Univ, Sch Pharmaceut Chem & Mat Engn, Taizhou, Zhejiang, Peoples R China.
    Qiu, Leyi
    Taizhou Univ, Sch Pharmaceut Chem & Mat Engn, Taizhou, Zhejiang, Peoples R China.
    Tang, Tian
    Taizhou Univ, Sch Pharmaceut Chem & Mat Engn, Taizhou, Zhejiang, Peoples R China.
    Solid emission color tuning of organic charge transfer cocrystals based on planar π-conjugated donors and TCNB2019In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 272, p. 96-101Article in journal (Refereed)
    Abstract [en]

    Two luminescent Charge Transfer (CT) cocrystals involving planar phenanthrene derivatives namely, formyl phenanthrene (FP) and acetyl phenanthrene (AP) as donors (D) and 1,2,4,5-tetracyanobenzene (TCNB) as an acceptor (A) building block, are formed by molecular self-assembly. Detailed structural and spectroscopic measurements elucidated the mixed stack sequence DADAD in the CT cocrystals. The solid supramolecular architecture for both the cocrystals forms 2D sheet, supported by the extended network of C-H center dot center dot center dot O, and C-H center dot center dot center dot N hydrogen bonds as evidenced by the crystallographic observation. Interestingly, the two cocrystals display tunable emissions compared to the blue emissions of donor compounds, which correlate with the formation of excited CT state between the donor and acceptor motifs as a result of mixed stack orientation. The nature of the CT interactions in the two cocrystals was further explored by applying density functional theoretical (DFT) studies. Such a supramolecular cocrystal approach provides a facile platform towards the design of new luminescent two component CT complexes with desired functionalities.

  • 20.
    Kibbou, Moussa
    et al.
    Moulay Ismail Univ, Fac Sci, Dept Phys, Lab Phys Materiaux Modelisat Syst LP2MS, Meknes, Morocco..
    Haman, Zakaryae
    Moulay Ismail Univ, Fac Sci, Dept Phys, Lab Phys Materiaux Modelisat Syst LP2MS, Meknes, Morocco..
    Khossossi, Nabil
    Moulay Ismail Univ, Fac Sci, Dept Phys, Lab Phys Materiaux Modelisat Syst LP2MS, Meknes, Morocco..
    Singh, Deobrat
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Essaoudi, Ismail
    Moulay Ismail Univ, Fac Sci, Dept Phys, Lab Phys Materiaux Modelisat Syst LP2MS, Meknes, Morocco..
    Ainane, Abdelmajid
    Moulay Ismail Univ, Fac Sci, Dept Phys, Lab Phys Materiaux Modelisat Syst LP2MS, Meknes, Morocco..
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Indian Inst Technol Ropar, Dept Phys, Rupnagar 140001, Punjab, India..
    Probing the electronic, optical and transport properties of halide double perovskites Rb2InSb(Cl,Br)6 for solar cells and thermoelectric applications2022In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 312, article id 123262Article in journal (Refereed)
    Abstract [en]

    Halide-based double perovskites have recently been promoted as high-performing semiconductors for photovoltaic and thermoelectricity applications owing to their outstanding efficiency, non-toxicity and ecological stability. In the framework of this research, we have systematically investigated the structural, mechanical, electronic, optical, and thermoelectric properties of Rb2InSb(Cl,Br)6 double halide perovskites. Based on Born stability and tolerance factor criteria, we have found that Rb2InSb(Cl,Br)6 are mechanically and structurally stable. Furthermore, we have performed a comprehensive evaluation of the electronic, optoelectronic, and thermoelectric characteristics. From the electronic band structure results, Rb2InSbCl6 and Rb2InSbBr6 exhibit direct semiconducting band gaps of 1.41 eV and 0.53 eV, respectively. The optical parameters of Rb2InSb(Cl,Br)6 reveal that our active structures have a higher dielectric constant, with maximum absorption in the visible range reaching over 5.68 = 105 cm1 and high optical conductivity (2.19 fs1 for Rb2InSbCl6 and 2.14 fs1 for Rb2InSbCl6). Moreover, the maximum limited spectroscopic efficiency reaches an impressive value of approximately 28.0% for Rb2InSbBr6 and 33.7% for Rb2InSbCl6. The thermoelectric properties were accurately calculated using the BoltzTraP simulation package. The obtained results reveal a significant electrical conductivity, a strong Seebeck coefficient (S 2756 mu VK1 at 300 K), and an average figure of merit close to one for both structures (ZT 1). Our findings suggest the versatility of these materials and could be used for a wide range of applications, including commercial solar cells and thermoelectricity.

  • 21. Larsson, A. -K
    et al.
    Norén, L.
    Withers, R. L.
    Rundlöf, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Coupled In/Te and Ni/vacancy ordering and the modulated crystal structure of a B8 type, Ni3 +/- xIn1-yTe2+y solid solution phase2007In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 180, no 10, p. 2723-2733Article in journal (Refereed)
    Abstract [en]

    The commensurate superstructures of a NiAs/Ni2In type parent structure, Ni3.32InTe2 and Ni3.12In0.86Te2.14 (q = gamma[0 0 1]*, gamma = 2/3) as well as one dimensionally incommensurate structure of Ni31nTe2 (gamma = 0.71) were refined from neutron powder diffraction data (R-wp = 4.77%, 4.53% and 4.91 % for the three structures, respectively, at 298 K). The commensurate structures were refined in the P6(3)/mmc space group (c = 3c(NiAs)). The stacking sequence at the hcp array is -In/Te/Te/- and the trigonal bipyrainidal site within the In layer, Ni(2), is partially occupied while it is empty in the Te layers. The octahedral position in between the In and Te layers, Ni(1a), is fully occupied while the octahedral position in between two adjacent Te layers, Ni(1b), is partially occupied. With decreasing In and Ni content, the modulation wave vector,, was found to increase continuously until gamma = 1. From this, crenel functions to describe the whole homogeneity range of the solid solution were constructed with the length of the atomic domains Delta(Te) = gamma (and hence Delta(In) = Delta(Ni) = 1-gamma) and Delta(Ni(1b)) = gamma/2 (and hence Delta(Ni(1a)) = 1-gamma/2) which were then used for the refinement of the incommensurate structure of Ni3InTe2. The corresponding effect in real space is that the single In layers separating double layers of Te, occur less frequent when y in increasing until at gamma = 1 the CdI2 type structure of Ni1+xTe2 is reached.

  • 22.
    Mattsson, Andreas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Lejon, Christian
    Bakardjieva, Snejana
    Stengl, Vaclav
    Österlund, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Characterisation, phase-stability and surface chemical properties of photocatalytic active Zr and Y co-doped anatase TiO2 nanoparticles2013In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 199, p. 212-223Article in journal (Refereed)
    Abstract [en]

    We report on the characterization, phase stability, surface chemical andphotocatalytic properties of Zr and Y co-doped anatase TiO2 nanoparticles prepared by homogenous hydrolysis methods using urea as precipitating agent. The materials were analyzed by scanning electron microscopy, X-ray diffraction, Raman spectroscopy, BET isotherm and BJH pore size distribution measurements. It is shown that Y and Zr ions replace Ti ions in the anatase TiO2 structures up to a critical total dopant concentration of approximately 13 wt%. The co-doped particles show increased phase stability compared to pure anatase TiO2nanoparticles. The anatase to rutile phase transformation is shown to be preceded by cation segregation and dissolution with concomitant precipitation of Y2Ti2-xZrxO7 and ZrTiO4. Co-doping modifies the optical absorption edge with a resulting attenuation of the Urbach tail. The band gap is slightly blue-shifted at high doping concentrations, and red shifted at lower doping concentrations. Formic acid adsorption was used as a probe molecule to investigate surfacechemical properties and adsorbate structures. It was found that the relative abundance ofmonodentate formate compared to bidentate coordinated formate decreases with increasing doping concentration. This is attributed to an increased surface acidity with increasing dopant concentration. Photodegradation of formic acid occurred on all samples. With mode-resolved in situ FTIR spectroscopy it is shown that the rate of photodegradation of monodentate formate species are higher than for bidentate formate species. Thus our results show that the trend ofdecreasing photo-degradation rate with increasing dopant concentration can be explained by the adsorbate structure, which is controlled by the acidity of the surface. 

    Download full text (pdf)
    JSSC_TiZrY_postprint
  • 23.
    Mirinioui, F.
    et al.
    Univ Hassan 1er, Lab Sci Mat Milieux & Modelisat LS3M, Khouribga 25000, Morocco..
    Manoun, Bouchaib
    Univ Hassan 1er, Lab Sci Mat Milieux & Modelisat LS3M, Khouribga 25000, Morocco..
    Tamraoui, Y.
    Univ Hassan 1er, Lab Sci Mat Milieux & Modelisat LS3M, Khouribga 25000, Morocco..
    Lazor, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Sequence of phase transitions induced by chemical composition and high temperature in [Ba2CaWO6]((1-x))[Sr2CaWO6](x) double perovskite tungsten oxides2015In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 232, p. 182-192Article in journal (Refereed)
    Abstract [en]

    [Ba2CaWO6](1-x)[Sr2CaWO6](x) (0 <= x <= 1) materials were synthesized by the high temperature solid state reaction and firing methods, and characterized using techniques of X-ray diffraction and Raman spectroscopy. The crystal structures were determined by Rietveld refinements on the laboratory X-ray powder diffraction data. As a function of composition, upon increasing the strontium content, the samples exhibit a sequence of three phase transitions: from cubic (Fm (3) over barm) to tetragonal (I4/m) to monoclinic structural phases (I2/m, P2(1)/n). These transitions have been confirmed by Raman studies Fm (3) over barm(x=0) -> I4/m(0.1 <= x <= 0.2) -> I2/m(0.3 <= x <= 0.5) -> P2(1)/n(0.6 <= x <= 1) Furthermore, increasing the temperature for the compositions [Ba2CaWO6](1-x)[Sr2CaWO6](x) (0.1 <= x < 1), manifests the P2(1)/n to I2/m, the I2/m to I4/m and the I4/m to Fm<(3)over bar>m phase transitions. For the compositions (0.1 <= x <= 0.2) the tetragonal to cubic phase transition is well illustrated. For the room temperature I2/m monoclinic compositions, two phase transitions were observed for all the compositions with x ranging from 0.3 to 0.5: from the monoclinic (I2/m) to tetragonal (I4/m), and from I4/m to Fm (3) over barm structures. Finally, for the room temperature P2(1)/n monoclinic compositions, only two phase transitions are observed in the temperature range probed by Raman spectroscopy, the temperature was not high enough to reach the tetragonal-to-cubic phase transition.

  • 24.
    Nedumkandathil, Reji
    et al.
    Stockholm Univ, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden..
    Kranak, Verina F.
    Stockholm Univ, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden..
    Johansson, Robert
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ångström, Jonas
    Balmes, Oliver
    Lund Univ, MAX Lab 4, Box 118, SE-22100 Lund, Sweden..
    Andersson, Mikael S.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Nordblad, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Scheicher, Ralph H.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Haussermann, Ulrich
    Stockholm Univ, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden..
    Hydrogenation induced structure and property changes in GdGa2016In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 239, p. 184-191Article in journal (Refereed)
    Abstract [en]

    Hydrides GdGaH were obtained by exposing the Zintl phase GdGa with the CrB structure to a hydrogen atmosphere at pressures from 1.5 to 50 bar and temperatures from 50 to 500 degrees C. Structural analysis by powder X-ray diffraction suggests that conditions with hydrogen pressures in a range between 15 and 50 bar and temperatures below 500 degrees C afford a uniform hydride phase with the NdGaH1.66 structure (Cmcm, a=3.9867(7) angstrom, b=12.024(2) angstrom, c=4.1009(6) angstrom) which hosts H in two distinct positions, H1 and H2. H1 is coordinated in a tetrahedral fashion by Gd atoms, whereas H2 atoms are inserted between Ga atoms. The assignment of the NdGaH1.66 structure is corroborated by first principles DFT calculations. Modeling of phase and structure stability as a function of composition resulted in excellent agreement with experimental lattice parameters when x=1.66 and revealed the presence of five-atom moieties Ga-H2-Ga-H2-Ga in GdGaH1.66. From in situ powder X-ray diffraction using synchrotron radiation it was established that hydrogenation at temperatures above 200 degrees C affords a hydride with x approximate to 1.3, which is stable up to 500 degrees C, and that additional H absorption, yielding GdGaH1.66, takes place at lower temperatures. Consequently, GdGaH1.66 desorbs H above T=200 degrees C. Without the presence of hydrogen, hydrides GdGaHx decompose at temperatures above 300 degrees C into GdH2 and an unidentified Gd-Ga intermetallics. Thus the hydrogenation of GdGa is not reversible. From magnetic measurements the Curie Weiss constant and effective magnetic moment of GdGaH1.66 were obtained. The former indicates antiferromagnetic interactions, the latter attains a value of similar to 8 mu B which is typical for compounds containing Gd3+ ions.

  • 25.
    Qin, Tao
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Ma, Ming
    Qin, Weiwei
    Xiao, Xinfeng
    Nikolajeff, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Rapid precipitation of Mg-doped fluoride-based submicron spheres and evolution study2018In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, no 260, p. 142-146Article in journal (Refereed)
  • 26.
    Ronneteg, Sabina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Lumey, M.W.
    Dronskowski, R
    Gelius, Ulrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Berger, Rolf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Felton, Solveig
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science.
    Nordblad, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science.
    Magnetic and electronic structure of the TlCo2S22004In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 177, no 9, p. 2977-2984Article in journal (Refereed)
    Abstract [en]

    An extensive investigation of the ferromagnetic compound TlCo2S2 has resulted in new information on the electronic and magnetic structure. Electronic structure calculations showed that magnetic ordering is energetically favorable with a clear driving force for ferromagnetic coupling within the cobalt layers. TlCo2S2 is metallic and the conductivity is due to holes in the valence band. XPS single crystal measurements did not show evidence of mixed oxidation states of cobalt. Neutron powder diffraction resulted in a ferromagnetic structure with the magnetic moment in the ab-plane. The derived magnetic moment of the cobalt atom is at 10 K and is in very good agreement with the value, at 10 K, inferred from the magnetic hysteresis curve.

  • 27.
    Sahlberg, Martin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Beran, Premysl
    Kollin Nielsen, Thomas
    Cerenius, Yngve
    Kádas, Krisztina
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science.
    Punkkinen, Marko P. J.
    Vitos, Levente
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science.
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science.
    Jensen, Torben R.
    Andersson, Yvonne
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    A new material for hydrogen storage; ScAl0.8Mg0.22009In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 182, no 11, p. 3113-3117Article in journal (Refereed)
    Abstract [en]

    A novel aluminium rich alloy for hydrogen storage has been discovered,   ScAl0.8Mg0.2, which has very promising properties regarding hydrogen   storage capacity, kinetics and stability towards air oxidation in   comparison to hydrogen absorption in state-of-the-art intermetallic   compounds. The absorption of hydrogen was found to be very fast, even   without adding any catalyst, and reversible. The discovered alloy   crystallizes in a CsCl-type structure, but decomposes to ScH2 and   Al(Mg) during hydrogen absorption. Detailed analysis of the hydrogen   absorption in ScAl0.8Mg0.2 has been performed using in situ synchrotron   radiation powder X-ray diffraction, neutron powder diffraction and   quantum mechanical calculations. The results from theory and   experiments are in good agreement with each other.

  • 28.
    Sahlberg, Martin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Zlotea, Claudia
    Latroche, Michel
    Andersson, Yvonne
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Fully reversible hydrogen absorption and desorption reactions with Sc(Al1-xMgx), x=0.0, 0.15, 0.202011In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 184, no 1, p. 104-108Article in journal (Refereed)
    Abstract [en]

    The hydrogen storage properties of Sc(Al1−xMgx), x=0.0, 0.15, 0.20, have been studied by X-ray powder diffraction, thermal desorption spectroscopy, pressure-composition-isotherms and scanning electron microscopy techniques. Hydrogen is absorbed from the gas phase at 70 kPa and 400 °C under the formation of ScH2 and aluminium with magnesium in solid solution. The reaction is fully reversible in vacuum at 500 °C and shows the hydrogenation–disproportionation–desorption-recombination (HDDR) behaviour. The activation energy of desorption was determined by the Kissinger method to 185 kJ/mol. The material is stable up to at least six absorption–desorption cycles and there is no change in particle size during cycling.

  • 29.
    Sahlberg, Martin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Zlotea, Claudia
    Moretto, Pietro
    Andersson, Yvonne
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    YMgGa as a hydrogen storage compound2009In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 182, no 7, p. 1833-1837Article in journal (Refereed)
    Abstract [en]

    The hydrogen absorption and desorption properties of the recently found ternary phase YMgGa have been studied. This compound absorbs 2.2 wt% hydrogen during the first cycle, but only 1.1 wt% can be stored reversibly for the following cycles under the applied pressure and temperature conditions. Hydrogen absorption and desorption properties were investigated by measuring the thermal desorption spectra and the pressure-composition isotherms while the crystal structure was determined using X-ray diffraction (XRD). The compound absorbs hydrogen at pressures above 0.2 MPa and 250 °C by decomposing into YH3 and MgGa. This reaction is reversed when heating the hydride in a He atmosphere; hydrogen is released and the YMgGa phase is partially recovered together with YGa2 and YH2. The reformation of YMgGa occurs at temperatures below 450 °C on the expenses of hydrogen desorption from YH2. This is not expected under these temperature conditions as YH2 normally does not desorb hydrogen below 800 °C.

  • 30.
    Sahlberg, Martin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Ångström, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Zlotea, Claudia
    Beran, Premsyl
    Latroche, Michel
    Pay Gómez, Ceasar
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Structure and hydrogen storage properties of the hexagonal Laves phase Sc(Al1-xNix)22012In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 196, p. 132-137Article in journal (Refereed)
    Abstract [en]

    The crystal structures of hydrogenated and unhydrogenated Sc(Al 1-xNi x) 2 Laves phases have been studied by combining several diffraction techniques and it is shown that hydrogen is situated interstitially in the A 2B 2-sites, which have the maximum number of scandium neighbours. The hydrogen absorption/desorption behaviour has also been investigated. It is shown that a solid solution of hydrogen forms in the mother compound. The hydrogen storage capacity exceeds 1.7 H/f.u. at 374 K, and the activation energy of hydrogen desorption was determined to 4.6 kJ/mol H 2. It is shown that these compounds share the same local coordination as Frank-Kasper-type approximants and quasicrystals, which opens up the possibility of finding many new hydride phases with these types of crystal structures.

  • 31.
    Shafeie, Samrand
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Fang, Hailiang
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Hedlund, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Nyberg, Axel
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    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.
    One step towards MnAl-based permanent magnets: Differences in magnetic, and microstructural properties from an intermediate annealing step during synthesis2019In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 274, p. 229-236Article in journal (Refereed)
    Abstract [en]

    The influence of an additional annealing step during synthesis on the preparation of MnAl based permanent magnet alloys has been investigated. Bulk samples of Mn55Al45C2 alloys were synthesized using induction heating through drop synthesis from 1400 °C. Samples produced using cooling directly from 1400 °C (from the melt), and from 1400 °C to an intermediate annealing step at 1200 °C for ~ 30 min before cooling were compared with respect to differences in phase purity, microstructure and magnetic properties. We found that the phase purity was significantly enhanced using the route with an intermediate annealing step at 1200 °C. From XRD the phase purity of the tau-phase was improved from ~ 91 wt% for the sample cooled directly from 1400 °C to ~ 95.1 - 99.5 wt% for the sample exposed to an intermediate annealing step before cooling. Additionally, EBSD, and SEM with EDS indicates a clear difference in the phase composition and differences in the distribution of the magnetic tau phase and the non-magnetic epsilon-, beta-, and gamma-phases. Magnetic properties also indicate, an improvement in saturation magnetization for the sample exposed to the extra annealing step during synthesis. Our results suggest that an intermediate annealing step in the production of MnAl based alloys will provide a simple way of achieving better phase purity and magnetic properties in the bulk alloy.

  • 32.
    Sveinbjörnsson, Dadi
    et al.
    Technical University of Denmark.
    Blanchard, Didier
    Technical University of Denmark.
    Myrdal, Jon Steinar Gardarsson
    Technical University of Denmark.
    Younesi, Reza
    Technical University of Denmark.
    Viskinde, Rasmus
    Technical University of Denmark.
    Riktor, Marit Dalseth
    Norby, Poul
    Technical University of Denmark.
    Vegge, Tejs
    Technical University of Denmark.
    Ionic conductivity and the formation of cubic CaH2 in the LiBH4–Ca(BH4)2 composite2014In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 211, no 0, p. 81-89Article in journal (Refereed)
    Abstract [en]

    Abstract LiBH4–Ca(BH4)2 composites were prepared by ball milling. Their crystal structures and phase composition were investigated using synchrotron X-ray diffraction and Rietveld refinement, and their ionic conductivity was measured using impedance spectroscopy. The materials were found to form a physical mixture. The composites were composed of α-Ca(BH4)2, γ-Ca(BH4)2 and orthorhombic LiBH4, and the relative phase quantities of the Ca(BH4)2 polymorphs varied significantly with LiBH4 content. The formation of small amounts of orthorhombic CaH2 and cubic CaH2 in a CaF2-like structure was observed upon heat treatment. Concurrent formation of elemental boron may also occur. The ionic conductivity of the composites was measured using impedance spectroscopy, and was found to be lower than that of ball milled LiBH4. Electronic band structure calculations indicate that cubic CaH2 with hydrogen defects is electronically conducting. Its formation along with the possible precipitation of boron therefore has an effect on the measured conductivity of the LiBH4–Ca(BH4)2 composites and may increase the risk of an internal short-circuit in the cells.

  • 33.
    Tseggai, M.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Mathieu, Roland
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Nordblad, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Tellgren, Roland
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Bau, L.V.
    Nam, D.N.H.
    Phuc, N.X.
    Khiem, N.V.
    André, G.
    Bourée, F.
    Effects of magnesium substitution on the magnetic properties of Nd0.7Sr0.3MnO32005In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 178, no 4, p. 1203-1211Article in journal (Refereed)
    Abstract [en]

    Effects of magnesium substitution on the magnetic properties of Nd0.7Sr0.3MnO3 have been investigated by neutron powder diffraction and magnetization measurements on polycrystalline samples of composition Nd0.7Sr0.3MnO3, Nd0.6Mg0.1Sr0.3MnO3, Nd0.6Mg0.1Sr0.3Mn0.9Mg0.1O3, and Nd0.6Mg0.1Sr0.3Mn0.8Mg0.2O3. The pristine compound Nd0.7Sr0.3MnO3 is ferromagnetic with a transition temperature occurring at about 210 K. Increasing the Mg-substitution causes weakened ferromagnetic interaction and a great reduction in the magnetic moment of Mn. The Rietveld analyses of the neutron powder diffraction (NPD) data at 1.5 K for the samples with Mg concentration, y=0.0 and 0.1, show ferromagnetic Mn moments of 3.44(4) and 3.14(4) μB, respectively, which order along the [001] direction. Below 20 K the Mn moments of these samples become canted giving an antiferromagnetic component along the [010] direction of about 0.4 μB at 1.5 K. The analyses also show ferromagnetic polarization along [001] of the Nd moments below 50 K, with a magnitude of almost 1 μB at 1.5 K for both samples. In the samples with Mg substitution of 0.2 and 0.3 only short range magnetic order occurs and the magnitude of the ferromagnetic Mn moments is about 1.6 μB at 1.5 K for both samples. Furthermore, the low-temperature NPD patterns show an additional very broad and diffuse feature resulting from short range antiferromagnetic ordering of the Nd moments.

  • 34.
    Wei, Xiao-Ping
    et al.
    Lanzhou Jiaotong Univ, Sch Math & Phys, Lanzhou 730070, Peoples R China..
    Sun, Weiwei
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. KTH Royal Inst Technol, Dept Mat Sci & Engn, SE-10044 Stockholm, Sweden..
    Zhang, Ya-Ling
    Chinese Acad Sci, Inst Modern Phys, Lanzhou 730000, Peoples R China..
    Sun, Xiao-Wei
    Lanzhou Jiaotong Univ, Sch Math & Phys, Lanzhou 730070, Peoples R China..
    Song, Ting
    Lanzhou Jiaotong Univ, Sch Math & Phys, Lanzhou 730070, Peoples R China..
    Wang, Ting
    Lanzhou Jiaotong Univ, Sch Math & Phys, Lanzhou 730070, Peoples R China..
    Zhang, Jia-Liang
    Lanzhou Jiaotong Univ, Sch Math & Phys, Lanzhou 730070, Peoples R China..
    Su, Hao
    Lanzhou Jiaotong Univ, Anning West Rd 88, Lanzhou 730070, Gansu, Peoples R China..
    Deng, Jian-Bo
    Lanzhou Univ, Dept Phys, Lanzhou 730000, Peoples R China..
    Zhu, Xing-Feng
    Nanjing Normal Univ, Dept Phys, Nanjing 210023, Peoples R China..
    Investigations on electronic, Fermi surface, Curie temperature and optical properties of Zr2CoAl2017In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 247, p. 97-104Article in journal (Refereed)
    Abstract [en]

    Using full-potential local-orbital minimum-basis along with spin-polarized relativistic Korringa-Kohn-Rostoker methods, we study the electronic, Fermi surface, Curie temperature and optical properties of Zr2CoAl alloy. The alloy with Li2AgSb and Cu2MnAl structures are compared in terms of magnetic properties, and the electronic structures in two structures are also discussed. According to the calculated electronic states, it finds that the Zr2CoAl with Li2AgSb structure is half-metallic ferromagnet with an integral magnetic moment of 2.00 mu(beta), meanwhile we also notice the d-d and p-d hybridizations are responsible for the formation of minority-spin gap, furthermore, the fat-bands are applied to discuss the mixture between d and p electrons in the vicinity of the Fermi level. The Fermi surfaces related to the valence bands are constructed, and it is found that the spin-up valence bands 26, 27 and 28 across the Fermi energy dominate the nature of electrons. By mapping the system onto a Heisenberg Hamiltonian, we obtain the exchange coupling parameters, and observe that the Zr(A)-Co(C) and Zr(A)-Zr(B) interactions provide a major contribution for exchange interactions. Based on the calculated exchange coupling parameters, the Curie temperature is estimated to be 287.86 K at equilibrium, and also the dependence of Curie temperature on lattice constant related to the tunable Curie temperature in Zr2CoAl alloy is studied. Finally, we report the optical properties of Zr2CoAl alloy, and present the photon energy dependence of the absorption, the optical conductivity and the loss function.

1 - 34 of 34
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