Blue-Light Emission from Nanocrystalline La_0.5Na_0.5TiO₃

Nanocrystalline La_0.5Na_0.5TiO₃ powders were prepared by the stearic acid-gel method, and the grain sizes could be controlled by varying annealing temperatures. The sizes were determined to be from 14 to 50nm using Scherrer's formula. A very strong blue-light emission band around 480nm was clearly observed in the nano-sized La_0.5Na_0.5TiO₃ with a grain size of 14nm at room temperature. Also, nano-size effects on the luminescence properties were investigated. These results could be explained with the aid of a self-trapped exciton model.