Neutron powder diffraction study of solid solution Li 1+ xTi 2− xIn xP 3O 12: I. 0.0 ≤ x ≤ 0.4

Abstract

Two polycrystalline samples of Li 1+ x Ti 2− x In x P 3O 12 prepared with compositions x = 0.25 and x = 0.40 have been analyzed by powder neutron diffraction. The x values found in the refinement were systematically lower, 0.12 and 0.15, respectively, than those required by chemical analysis. The discrepancy in the x values is explained by formation of a parasitic phase coexisting with the main phase. The structure framework of the analyzed samples (actually x = 0.12 and 0.15) is of the NASICON type, with Ti and In atoms randomly distributed among octahedral sites. Lithium atoms are distributed over octahedral and eight-coordinated sites. The octahedral Li(1) site is almost filled, with a relatively large Li(1)O distance, 2.29 Å, leaving Li(1) ions enough room to jump into Li(2) sites. The latter sites are only partially occupied by Li(2) ions. A large temperature factor associated with a split position inside the eight-coordinated cavity suggests that the Li(2) ions are in a highly disordered configuration.