A comparison of the transport properties of lithium-stuffed garnets and the conventional phases Li{sub 3}Ln{sub 3}Te{sub 2}O{sub 12}

Journal Article · Tue Feb 15 00:00:00 EST 2011 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2010.12.021· OSTI ID:21494193

Yip, Thomas W.S.; O'Neill, Gemma; O'Callaghan, Michael P ^[1]

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1. WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, Thomas Graham Building, 295 Cathedral Street, Glasgow G1 1XL (United Kingdom)

The structures of new phases Li{sub 6}CaLa{sub 2}Sb{sub 2}O{sub 12} and Li{sub 6.4}Ca{sub 1.4}La{sub 2}Sb{sub 2}O{sub 12} have been characterised using neutron powder diffraction. Rietveld analyses show that both compounds crystallise in the space group la3-bar d and contain the lithium cations in a complex arrangement with occupational disorder across oxide tetrahedra and distorted oxide octahedra, with considerable positional disorder in the latter. Variable temperature neutron diffraction experiments on Li{sub 6.4}Ca{sub 1.4}La{sub 2}Sb{sub 2}O{sub 12} show the structure is largely invariant with only a small variation in the lithium distribution as a function of temperature. Impedance spectroscopy measurements show that the total conductivity of Li{sub 6}CaLa{sub 2}Sb{sub 2}O{sub 12} is several orders of magnitude smaller than related lithium-stuffed garnets with {sigma}=10{sup -7} S cm{sup -1} at 95 {sup o}C and an activation energy of 0.82(3) eV. The transport properties of the conventional garnets Li{sub 3}Gd{sub 3}Te{sub 2}O{sub 12}, Li{sub 3}Tb{sub 3}Te{sub 2}O{sub 12}, Li{sub 3}Er{sub 3}Te{sub 2}O{sub 12} and Li{sub 3}Lu{sub 3}Te{sub 2}O{sub 12} have been evaluated and consistently show much lower values of conductivity, {sigma}{<=}4.4x10{sup -6} S cm{sup -1} at 285 {sup o}C and activation energies in the range 0.77(4){<=}E{sub a}/eV{<=}1.21(3). -- Graphical abstract: The lithium-stuffed garnets Li{sub 6}CaLa{sub 2}Sb{sub 2}O{sub 12} and Li{sub 6.4}Ca{sub 1.4}La{sub 1.6}Sb{sub 2}O{sub 12} accommodate lithium in a complex distribution across oxide tetrahedra and octahedra. The total conductivity of Li{sub 6}CaLa{sub 2}Sb{sub 2}O{sub 12} is considerably lower than reported for related fast-ion conducting garnets due to a much larger intra-grain contribution to the resistivity than is commonly found for this family of compounds. Research highlights: {yields} Lithium stuffed garnets have a complex distribution of Li{sup +} across multiple sites. {yields} They show fast lithium ion conductivity with an activation energy of 0.82 eV. {yields} This conductivity is much lower than related garnets due to grain boundary effects. {yields} The stoichiometric garnets show minimal ion mobility.

• OSTI ID: 21494193
• Journal Information: Journal of Solid State Chemistry, Vol. 184, Issue 2; Other Information: DOI: 10.1016/j.jssc.2010.12.021; PII: S0022-4596(10)00567-0; 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
CRYSTALLOGRAPHY
GARNETS
GRAIN BOUNDARIES
IMPEDANCE
ION MOBILITY
IONIC CONDUCTIVITY
LITHIUM COMPOUNDS
LITHIUM IONS
MILLI EV RANGE
NEUTRON DIFFRACTION
OXIDES
RARE EARTH COMPOUNDS
SPACE GROUPS
SPECTROSCOPY
TELLURIUM COMPOUNDS
TEMPERATURE DEPENDENCE
ALKALI METAL COMPOUNDS
CHALCOGENIDES
CHARGED PARTICLES
COHERENT SCATTERING
DIFFRACTION
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ENERGY
ENERGY RANGE
IONS
MICROSTRUCTURE
MINERALS
MOBILITY
OXYGEN COMPOUNDS
PARTICLE MOBILITY
PHYSICAL PROPERTIES
SCATTERING
SILICATE MINERALS
SYMMETRY GROUPS