Abstract
Polycrystalline samples of the garnets Li3+xNd3Te2-xSbxO12 have been prepared by high temperature
solid state synthesis. X-ray and neutron powder diffraction data show that all compounds crystallize in
the space group Ia3j
d with lattice parameters in the range 12.55576(12) Å for x ) 0.05 to 12.6253(2) Å
for x ) 1.5. The lithium is distributed over a mixture of oxide tetrahedra and heavily distorted octahedra.
Increasing the lithium content in these compounds leads to the introduction of vacancies onto the tetrahedral
position and an increasing concentration of lithium found in the octahedra. The latter exhibit considerable
positional disorder with two lithium cations positions within each octahedron. Impedance measurements
show fast ion conduction with an activation energy of ca. 0.59(6) eV that is largely invariant with
composition. Solid-state Li NMR measurements indicate that there is no exchange of lithium between
the different coordination environments. These results indicate that lithium conduction in the garnet
structure occurs exclusively via a network of edge-linked distorted oxide octahedra and that the tetrahedrally
coordination lithium plays no part in the transport properties.
Original language | English |
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Pages (from-to) | 2360-2369 |
Number of pages | 10 |
Journal | Chemistry of Materials |
Volume | 20 |
Issue number | 6 |
DOIs | |
Publication status | Published - 25 Mar 2008 |
Keywords
- garnets
- ion conductivity
- lithium