Electron microscopy characterization of hot-pressed Al substituted Li7La3Zr2O12

Hot-pressing was used to prepare a dense (97% relative density) cubic Al substituted Li7La3Zr2O12 material at temperatures lower than typically used for solid-state and/or liquid phase sintering. Electron microscopy analysis revealed equiaxed grains, grain boundaries, and triple junctions free of amorphous and second phases and no Al segregation at grain boundaries. These results suggest that Al2O3 and/or Al cannot act as a sintering aid by reducing grain boundary mobility. If Al2O3 acts as a sintering aid its main function is to enter the lattice as Al to increase the point defect concentration of the slowest moving species.