Synthesis of lithium garnets from La2Zr2O7 pyrochlore

An attempt has been made in this work to prepare lithium garnets from La2Zr2O7 (LZ) Pyrochlore. Systematic investigation has been carried out on direct solid-state reaction of LZ pyrochlore with lithium-lanthanum oxides Li7LaO5 (LL) and lithium-aluminum-lanthanum oxides Li6.28Al0.24LaO5 (LAL) to understand the role of 12 pyrochlore in the formation of tetragonal and high Li+ conductive cubic phase lithium garnets. Structural studies indicated the stabilization of LLZ (using LZ + LL) and Li6.28Al0.24La3Zr2O12 (using LZ + LAL) in tetragonal phase at 950 degrees C and into high Li+ conductive cubic phase only at the sintering temperature of 1200 degrees C. However, Li6.28Al0.24La3Zr2O12 prepared from the reactants LiOH center dot H2O, La2O3, Al2O3 and ZrO2 stabilized into high Li+ conductive cubic phase at 950 degrees C. Among the investigated samples, the lithium deficient and Al doped LALZ-cs sintered at 1200 degrees C exhibits maximized relative density (93%) and total (bulk + grain-boundary) Li+ conductivity of 4.43 x 10(-4) S cm(-1) at 30 degrees C with minimum activation energy of 0.37 eV. (C) 2015 Elsevier B.V. All rights reserved.