Luminescence investigation of Ce incorporation in garnet-type Li7La3Zr2O12

The effects of the incorporation of Ce on the luminescence of tetragonal garnet-type Li7La3Zr2O12 (LLZO) were examined. Undoped and Ce-doped LLZO powders with nominal compositions of Li7(La1-x Cex)3Zr2O12 with x = 0, 0.005, 0.01, 0.03, and 0.05 were synthesized via conventional solid state reaction. X-ray diffraction (XRD) revealed the structural evolution from tetragonal to cubic LLZO, together with Li2ZrO3 and Ce4O7 minor phases upon Ce incorporation. Undoped LLZO exhibited a single luminescence band centered at 2.84 eV that was quenched by the incorporation of Ce. A Gaussian band deconvolution analysis of the radioluminescence (RL) spectra suggested that Ce occupied two distinct crystallographic sites when replacing for La, with emission bands centered at 2.41 and 2.78 eV. The Gaussian band deconvolution analysis of RL spectra up to ∼250 °C revealed thermal quenching reduced the intensity by about half at 50-60 °C, with negligible emission detected at about 250 °C.