Defect control and lithium-ion conducting properties of layered perovskite oxides Li_2SrTa_2O_7

摘要

Lithium-ion conducting properties were investigated for a layered perovskite oxide Li_2SrTa_2O_7 (LST) and defect-controlled LST, synthesized via solid state reactions. The ionic conductivities of A-site solid solutions Li_2[Sr-(La_(2/3)□_(1/3))-(La_(1/2)Li_(1/2))]Ta_2O_7 (□ denotes vacancy.) suggested that lithium ions migrate in the Li-layer. The conductivity of Li-deficient (Li_(2-z)D_z)(La_zSr_(1-z))Ta_2O_7 increased dramatically from 4.2 × 10~(-6) S cm~(-1) (z = 0, LST) to 1.6 × 10~(-3) S cm~(-1) (z = 0.2) at 400°C with increasing Li-vacancy concentration. This result obviously indicates that the conductivity of LST originate from the Li migration through vacancies in the Li-layer.