Study on stabilization of cubic Li7La3Zr2O12 by Ge substitution in various atmospheres

Abstract

Stabilization of high Li ion conductive cubic Li7La3Zr2O[Formula: see text] (LLZ) by Ge substitution in air, N2/O2 and N2 atmospheres are studied by high temperature XRD (HT-XRD) of Ge-added tetragonal LLZ (Ge-LLZ). A formation of low temperature cubic phase caused by CO2 absorption during storage of the Ge-LLZ is observed at about 160[Formula: see text]C in all atmospheres. Additionally, impurity formation of La2Zr2O7 and La2O3 also occurs in all atmospheres. On the other hand, stabilization of cubic phase by substitution of Ge is largely influenced by the atmosphere. The cubic phase is observed at 40[Formula: see text]C after heating Ge-LLZ to 700[Formula: see text]C in air while only tetragonal phase appeared after heating in N2/O2. It is concluded that the heating atmosphere largely influences substitution of Ge, resulting in stabilization of the high Li ion conductive cubic phase.