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  • 1.
    Biendicho, Jordi Jacas
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). STFC Rutherford Appleton Laboratory, England.
    Roberts, Matthew
    Noréus, Dag
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Lagerqvist, Ulrika
    Smith, Ronald I.
    Svensson, Gunnar
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Norberg, Stefan T.
    Eriksson, Sten G.
    Hull, Stephen
    In situ investigation of commercial Ni(OH)(2) and LaNi5-based electrodes by neutron powder diffraction2015Inngår i: Journal of Materials Research, ISSN 0884-2914, E-ISSN 2044-5326, Vol. 30, nr 3, s. 407-416Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Electrochemical reactions at both positive and negative electrodes in a nickel metal hydride (Ni-MH) battery during charge have been investigated by in situ neutron powder diffraction. Commercially available beta-Ni(OH)(2) and LaNi5-based powders were used in this experiment as positive and negative electrodes, respectively. Exchange of hydrogen by deuterium for the beta-Ni(OH)(2) electrode was achieved by ex situ cycling of the cell prior to in situ measurements. Neutron diffraction data collected in situ show that the largest amount of deuterium contained at the positive electrode is de-intercalated from the electrode with no phase transformation involved up to similar to 100 mA h/g and, in addition, the 110 peak width for the positive electrode increases on charge. The negative electrode of composition MmNi(3.6)Al(0.4)Mn(0.3)Co(0.7), where Mm = Mischmetal, exhibits a phase transformation to an intermediate hydride gamma phase first and then to the beta phase on charge. Unit cell dimensions and phase fractions have been investigated by Rietveld refinement of the crystal structure.

  • 2.
    Biendicho, Jordi Jacas
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). STFC Rutherford Appleton Laboratory, England.
    Roberts, Matthew
    Offer, Colin
    Noréus, Dag
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Widenkvist, Erika
    Smith, Ronald I.
    Svensson, Gunnar
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Edström, Kristina
    Norberg, Stefan T.
    Eriksson, Sten G.
    Hull, Stephen
    New in-situ neutron diffraction cell for electrode materials2014Inngår i: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 248, s. 900-904Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A novel neutron diffraction cell has been constructed to allow in-situ studies of the structural changes in materials of relevance to battery applications during charge/discharge cycling. The new design is based on the coin cell geometry, but has larger dimensions compared to typical commercial batteries in order to maximize the amount of electrode material and thus, collect diffraction data of good statistical quality within the shortest possible time. An important aspect of the design is its modular nature, allowing flexibility in both the materials studied and the battery configuration. This paper reports electrochemical tests using a Nickel-metal-hydride battery (Ni-MH), which show that the cell is able to deliver 90% of its theoretical capacity when using deuterated components. Neutron diffraction studies performed on the Polaris diffractometer using nickel metal and a hydrogen-absorbing alloy (MH) clearly show observable changes in the neutron diffraction patterns as a function of the discharge state. Due to the high quality of the diffraction patterns collected in-situ (i.e. good peak-to-background ratio), phase analysis and peak indexing can be performed successfully using data collected in around 30 min. In addition to this, structural parameters for the beta-phase (charged) MH electrode obtained by Rietveld refinement are presented.

    Fulltekst (pdf)
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  • 3.
    Biendicho, Jordi Jacas
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). STFC Rutherford Appleton Laboratory, England.
    Shafeie, Samrand
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Frenck, Louise
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). Pierre & Marie Curie University, France.
    Gavrilova, Daria
    Böhme, Solveigh
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). Chemnitz University of Technology, Germany.
    Bettanini, A. M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). Universita Ca Foscari Venezia, Italy.
    Svedlindh, Peter
    Hull, Steve
    Zhe, Zhao
    Istomin, S. Y.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Grins, Jekabs
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Svensson, Gunnar
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Synthesis and characterisation of perovskite SrxY1-xFeO3-d (=.63≤x<1) and Sr0.75Y0.25Fe1-yMyO3-d (M=Cr, Mn, Ni) (y= 0.2, 0.33, 0.5)2013Inngår i: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 200, s. 30-38Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Oxygen-deficient ferrates with the cubic perovskite structure SrxY1-xFeO3-d were prepared in air (0.71 ≤ x ≤ 0.91) as well as in N2 (x=0.75 and 0.79) at 1573K. The oxygen content of the compounds prepared in air increases with increasing strontium content from 3-δ=2.79(2) for x=0.75 to 3-δ=2.83(2) for x=0.91. Refinement of the crystal structure of Sr0.75Y0.25FeO2.79 using TOF 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 high-resolution electron microscopy (HREM) studies of Sr0.75Y0.25FeO2.79 reveal a modulation along <100>p with G± ~0.4<100>p indicating a local ordering of oxygen vacancies. Magnetic susceptibility measurements at 5-390K show spin-glass behaviour with dominating antiferromagnetic coupling between the magnetic moments of Fe cations. Among the studied compositions, Sr0.75Y0.25FeO2.79 shows the lowest thermal expansion coefficient (TEC) of 10.5 ppm K-1 in air at 298-673K. At 773-1173K TEC increases up to 17.2 ppm K-1 due to substantial reduction of oxygen content. The latter also results in a dramatic decrease of the electrical conductivity in air above 673K. Partial substitution of Fe by Cr, Mn and Ni according to the formula Sr0.75Y0.25Fe1-yMyO3-δ (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 Sr0.75Y0.25FeO2.79. Only M=Ni has increased electrical conductivity compared to un-doped Sr0.75Y0.25FeO2.79.

    Fulltekst (pdf)
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  • 4. Norberg, Stefan T.
    et al.
    Hull, Stephen
    Eriksson, Sten G.
    Ahmed, Istaq
    Kinyanjui, Francis
    Biendicho, Jordi Jacas
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Pyrochlore to fluorite transition: the y 2(ti1 xzrx)(2)o 7 (0.0 <= x <= 1.0) system2012Inngår i: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 24, nr 22, s. 4294-4300Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The structural properties of the system Y-2(Ti1-xZrx)(2)O-7 have been investigated using the neutron powder diffraction technique, including a detailed analysis of the total scattering using reverse Monte Carlo modeling to probe the short-range ion-ion correlations over sample range 0.0 <= x <= 1.0. The average crystal structure shows a continuous transformation from the long-range ordered pyrochlore structure (Fd (3) over barm, a = 10.0967(1) angstrom, Z = 8, for x = 0.00, Y2Ti2O7) to a disordered fluorite structure (Fm (3) over barm, a = 5.2042(1) angstrom, Z = 1, for x = 1.00, Zr2Y2O7) in agreement with previous reports. However, on increasing x the disordering of both the cation and the anion sublattices occurs in stages, with the Zr4+ initially only substituting onto the Ti4+ site and adopting a cubic, rather than octahedral, local anion environment. At concentrations in excess of x approximate to 0.4 there is a gradual disordering of the Y3+, Ti4+, and Zr4+ species over all the cation sites, coupled with a redistribution of the O2- which initially only involves those anions on the O1 sites. The relationship between the composition dependences of the structure properties and the ionic conductivity is discussed.

  • 5. Roberts, Matthew
    et al.
    Biendicho, Jordi Jacas
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Hull, Stephen
    Beran, Premysl
    Gustafsson, Torbjörn
    Svensson, Gunnar
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Edström, Kristina
    Design of a new lithium ion battery test cell for in-situ neutron diffraction measurements2013Inngår i: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 226, s. 249-255Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper introduces a new cell design for the construction of lithium ion batteries with conventional electrochemical performance whilst allowing in situ neutron diffraction measurement. A cell comprising of a wound cathode, electrolyte and anode stack has been prepared. The conventional hydrogen-containing components of the cell have been replaced by hydrogen-free equivalents. The electrodes are fabricated using a PTFE binder, the electrolyte consists of deuterated solvents which are supported in a quartz glass fibre separator. Typical battery performance is reported using the hydrogen-free components with a specific capacity of 140 mA h g(-1) being observed for LiFePO4 at a rate of 0.2 C. Neutron diffraction patterns of full cells were recorded with phase change reactions monitored. When aluminium packaging was used a better signal to noise ratio was obtained. The obtained atomic positions and lattice parameters for all cells investigated were found to be consistent with parameters refined from the diffraction pattern of a powder of the pure electrode material. This paper highlights the pertinent points in designing cells for these measurements and addresses some of the problems.

  • 6.
    Svensson, Gunnar
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Samain, Louise
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Biendicho, Jordi Jacas
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). Catalonia Institute for Energy Research, Spain; STFC Rutherford Appleton Laboratory, UK.
    Mahmoud, Abdelfattah
    Hermann, Raphaël P.
    Istomin, Sergey Ya.
    Grins, Jekabs
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Crystal Structure and Coordination of B-Cations in the Ruddlesden-Popper Phases Sr3-xPrx(Fe1.25Ni0.75)O7- (0 x 0.4)2018Inngår i: Inorganics, ISSN 2304-6740, Vol. 6, nr 3, artikkel-id 89Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Compounds Sr3-xPrxFe1.25Ni0.75O7- with 0 x 0.4 and Ruddlesden-Popper n = 2 type structures were synthesized and investigated by X-ray and neutron powder diffraction, thermogravimetry, and Mossbauer spectroscopy. Both samples, prepared at 1300 degrees C under N-2(g) flow and samples subsequently air-annealed at 900 degrees C, were studied. The structures contained oxygen vacancies in the perovskite layers, and the Fe/Ni cations had an average coordination number less than six. The oxygen content was considerably higher for air-annealed samples than for samples prepared under N-2, 7 - = similar to 6.6 and similar to 5.6 per formula unit, respectively. Mossbauer data collected at 7 K, below magnetic ordering temperatures, were consistent with X-ray powder diffraction (XRD) and neutron powder diffraction (NPD) results. The electrical conductivity was considerably higher for the air-annealed samples and was for x = 0.1 similar to 30 Scm(-1) at 500 degrees C. The thermal expansion coefficients were measured in air between room temperature and 900 degrees C and was found to be 20-24 ppmK(-1) overall.

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