Ionic Conductivity and Microstructural Peculiarities of Lithium Conducting Perovskite Solid Solutions

摘要

The structure, microstructure and conductivity parameters of perovskite-like lithium-lanthanum titanates (La0.5Li0.3~(3+)x)TiO_3 (LLT) (I) and LLT-based solid solutions (La0.5Li0.5)[Ti1-x(M0.5Nb0.5)x]O_3 with M = Al (II), Ga (III) have been studied. Ionic conductivity has been found to decrease in solid solutions (I) with lithium content increasing due to both the cell volume and the A-site vacancy content decrease. A decrease in the conductivity due to the unit cell contraction with increasing x in case of solid solutions (II) has been revealed. The unit cell volume has been found to enhance with increasing x while the conductivity decreases due to the interatomic interaction change in case of B-site substitution for Ti in solid solutions (III). The solid solution (I) with x=0.17 have been found to undergo the first order phase transition at ~900 K without crystal symmetry change. The subdivision of grains of the ceramics (I, II) into nanometer ranges has been revealed by the AFM method.