Thermally Stimulated Light Reflection and Photoluminescence of BaTiO₃

Perovskites have been attracting attention because of their considerable luminescence properties. A conventional perovskite such as BaTiO₃ has no intrinsic photoluminescence. Doping with rare metals, nanocrystallization, and addition of organometallic halides induce significant photoluminescence and photovoltages. Here, we report anomalous light reflection and photoluminescence of BaTiO₃ on heating. Light absorption shifted from the near-ultraviolet region to the visible region on heating. The small emission peaks at around 400-500 nm disappeared and new peaks appeared above 800 nm; the quantum yields of these peaks were less than 1% and more than 7%, respectively.