Preparation and optical properties of Eu2+ and Sm3+ co-doped glass ceramic phosphors emitting white color by violet laser excitation

Eu2+ and Sm3+ co-doped silicate glasses were prepared under reducing atmosphere in a system SiO2-Al2O3-CaO and the glass-ceramics were obtained by heat-treatment at temperatures between 1000 and 1400°C. Broad emission band were observed between 400 and 550 nm due to the 5d→4f transition of Eu2+, as well as sharp emission peaks at 563, 600, 646 and 713 nm due to the 4f→4f transition of Sm3+ in the samples. Emission color became white under ultraviolet or violet excitation for the glass ceramics heat-treated at above 1100°C. Ceramming temperature dependence of the color coordinates, emission spectra were investigated and discussed with the precipitated crystal phases. We have successfully obtained the glass ceramic phosphor emitting white color, suitable for a white LED without organic resin for power illumination.