Tricolor luminescence in rare earth doped CaZrO3 perovskite oxides

Intense tricolor photoluminescence under ultraviolet excitation was observed from Eu–Mg codoped CaZrO3 and Tb–Mg codoped CaZrO3. The RGB tricolor was obtained from a single host lattice of perovskite-type CaZrO3 by just varying a doped rare earth ion and its concentration. Red luminescence was observed in Eu–Mg codoped CaZrO3, and green and blue luminescence was observed in Tb–Mg codoped CaZrO3. The color of the luminescence in Tb–Mg codoped CaZrO3 changed with Tb concentration due to the cross relaxation in Tb ions; green color was seen at high concentration and blue color at low concentration. In comparison with other perovskite host lattices, these zirconates showed more intense luminescence than hafnates and stannates. In addition, Mg codoping with the rare earth ions markedly increased the luminescence intensity. It is considered that the intense luminescence in the zirconates is attributed to the large crystal structural distortion of CaZrO3 and the local lattice distortion around the rare earth ions enhanced by Mg substitution at Ca sites.