Perovskite-type compounds were synthesized, and their crystal structures and Li-ion conductivities were characterized. The symmetry of the perovskite lattice ranged from cubic for La¼Li¼TaO3, to tetragonal for Nd¼Li¼TaO3 and Sm¼Li¼TaO3, and to orthorhombic for Y¼Li¼TaO3. An alternating ordering of ions and vacancies at the A-sites was detected in Nd¼Li¼TaO3, Sm¼Li¼TaO3 and Y¼Li¼TaO3. The cube root of the sub-cell volume decreased with decreasing ionic radius of the lanthanide cations; which acted as spacers in the perovskite lattice. As the cube root of the sub-cell volume decreased from La¼Li¼TaO3 to Y¼Li¼TaO3, the bulk conductivity at 400K decreased from 1.4 x 10-1S/m to 5.0 x 10-7S/m. The activation energy increased from 0.35 to 0.85eV. It was concluded that the sub-cell volume, and ordering at the A-sites, were major factors which affected Li-ion conduction in these conductors.

Lithium Ion Conduction in A-Site Deficient Perovskites. K.Mizumoto, S.Hayashi: Solid State Ionics, 1999, 116[3-4], 263-9