Effect of sintering process on the microstructure and ionic conductivity of Li7–La3Zr2–Ta O12 ceramics

Abstract

Li 7– x La 3 Zr 2– x Ta x O 12 (0 ≤ x ≤ 1) ceramics were prepared by pressureless sintering at 1230 °C in air. XRD, SEM and Impedance test were used to characterize the crystal structure, microstructure and electrical performance of Li 7– x La 3 Zr 2– x Ta x O 12 ceramics. According to XRD data, the specimens with x ≥ 0.2 sintered at 1230 °C for 1 h exhibit a cubic garnet structure without impurities. The Ta-doped specimens sintered at 1230°C for 1 h show high relative density of 91.6%–93.9%. Ta doping has a certain effect on the Li vacancy concentration, lithium arrangement, movable Li + concentration and microstructure of the LLZO ceramic. The Li 6.6 La 3 Zr 1.6 Ta 0.4 O 12 ceramic sintered at 1230°C for 1 h has the highest total conductivity of 6.01 × 10 –4 S·cm –1 at room temperature and the lowest activation energy of 0.27 eV.