The relationship between Li ion conductivity and crystal structure for ordered perovskite compounds, (La2/3−1/3pLip)(Mg1/2W1/2)O3 (p=0.05, 0.11 and 0.14)

We synthesized furnace-cooled (La2/3−1/3pLip)(Mg1/2W1/2)O3 (LLMW) and quenched (La2/3−1/3pLip)(Mg1/2W1/2)O3 (LLMWq) and investigated Li ion conductivity for these compounds. Activation energy was found to decrease with Li content for LLMW and LLMWq, while the obvious lattice contraction accompanied with Li content was not observed. For LLMW, ordered arrangement of the A-site ions was varied with Li content which seems to be responsible for the decrease in the activation energy. As results of structure refinements of LLMWq, it was revealed that covalent character of W–O bond increased with Li content. It is considered that the Coulomb repulsion between W and Li ions dominates the activation energy and that the increase in the covalent character of the W–O bond with Li content is the reason for the decrease in the activation energy.