Synthesis, structural characterization and Li{sup +} ion conductivity of a new vanado-molybdate phase, LiMg{sub 3}VMo{sub 2}O{sub 12}

Journal Article · Mon Nov 15 00:00:00 EST 2010 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2010.08.042· OSTI ID:21494113

Souza, Sharon A. de ^[1]; Sheptyakov, Denis ^[2]; Reeves-McLaren, Nik; Pasero, Denis; West, Anthony R ^[1]

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1. Department of Engineering Materials, Sir Robert Hadfield Building, University of Sheffield, Mappin Street, Sheffield S1 3JD (United Kingdom)
2. Laboratory for Neutron Scattering, ETHZ and PSI, CH-5232 Villigen PSI (Switzerland)

A new vanado-molybdate LiMg{sub 3}VMo{sub 2}O{sub 12} has been synthesized, the crystal structure determined an ionic conductivity measured. The solid solution Li{sub 2-z}Mg{sub 2+z}V{sub z}Mo{sub 3-z}O{sub 12} was investigated and the structures of the z=0.5 and 1.0 compositions were refined by Rietveld analysis of powder X-ray (XRD) and powder neutron diffraction (ND) data. The structures were refined in the orthorhombic space group Pnma with a{approx}5.10, b{approx}10.4 and c{approx}17.6 A, and are isostructural with the previously reported double molybdates Li{sub 2}M{sub 2}(MoO{sub 4}){sub 3} (M=M{sup 2+}, z=0). The structures comprise of two unique (Li/Mg)O{sub 6} octahedra, (Li/Mg)O{sub 6} trigonal prisms and two unique (Mo/V)O{sub 4} tetrahedra. A well-defined 1:3 ratio of Li{sup +}:Mg{sup 2+} is observed in octahedral chains for LiMg{sub 3}VMo{sub 2}O{sub 12}. Li{sup +} preferentially occupies trigonal prisms and Mg{sup 2+} favours octahedral sheets. Excess V{sup 5+} adjacent to the octahedral sheets may indicate short-range order. Ionic conductivity measured by impedance spectroscopy (IS) and differential scanning calorimetry (DSC) measurements show the presence of a phase transition, at 500-600 {sup o}C, depending on x. A decrease in activation energy for Li{sup +} ion conductivity occurs at the phase transition and the high temperature structure is a good Li{sup +} ion conductor, with {sigma}=1x10{sup -3}-4x10{sup -2} S cm{sup -1} and E{sub a}=0.6 to 0.8 eV. - Graphical abstract: A new vanado-molybdate LiMg{sub 3}VMo{sub 2}O{sub 12} has been synthesized and the crystal structure determined. Ionic conductivity measurements show the presence of a phase transition, at 500-600 {sup o}C. A large decrease in activation energy for Li{sup +} ion conductivity occurs at the phase transition and the high temperature structure is a good Li{sup +} ion conductor. Display Omitted

• OSTI ID: 21494113
• Journal Information: Journal of Solid State Chemistry, Vol. 183, Issue 11; Other Information: DOI: 10.1016/j.jssc.2010.08.042; PII: S0022-4596(10)00390-7; Copyright (c) 2010 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ACTIVATION ENERGY
CALORIMETRY
IMPEDANCE
IONIC CONDUCTIVITY
LITHIUM COMPOUNDS
LITHIUM IONS
MAGNESIUM COMPOUNDS
MAGNESIUM IONS
MOLYBDATES
NEUTRON DIFFRACTION
ORTHORHOMBIC LATTICES
PHASE TRANSFORMATIONS
SOLID SOLUTIONS
SPACE GROUPS
SPECTROSCOPY
SYNTHESIS
TEMPERATURE RANGE 0400-1000 K
VANADIUM COMPOUNDS
VANADIUM IONS
X-RAY DIFFRACTION
ALKALI METAL COMPOUNDS
ALKALINE EARTH METAL COMPOUNDS
CHARGED PARTICLES
COHERENT SCATTERING
CRYSTAL LATTICES
CRYSTAL STRUCTURE
DIFFRACTION
DISPERSIONS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ENERGY
HOMOGENEOUS MIXTURES
IONS
MIXTURES
MOLYBDENUM COMPOUNDS
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
REFRACTORY METAL COMPOUNDS
SCATTERING
SOLUTIONS
SYMMETRY GROUPS
TEMPERATURE RANGE
TRANSITION ELEMENT COMPOUNDS