A novel white Y(TiHf)O: Eu phosphors regulated by HfO exhibiting low color shifting for high temperature.

The development of white phosphors that can be activated in near-ultraviolet light is highly important in the field of LED lighting. In this work, a series of color-tunable Y(TiHf)O:Eu phosphors were prepared by adjusting the HfO and Eu concentrations. In particular, white Y(TiHf)O:Eu phosphors were successfully synthesized and emitted a broad band covering the entire visible light region upon excitation with 340 nm UV light. The white banded materials were composed of Eu and Eu emissions and HfO defect emission. The formation of Eu ions was caused by the introduction of HfO which causes self-reduction of Eu ions but does not require additional reducing agents. The white Y(TiHf)O:Eu phosphors exhibit low color shifting at high temperature, which is very important for LED applications. The chromaticity shift of the Y(TiHf)O:0.2Eu phosphor is 2.83 × 10 at 503 K, which is only 54.8 % that of commercial three-color white phosphors at the same temperature. The Ra value did not decrease significantly with increasing temperature and reached 90.2 at 383 K. Y (TiHf)O:0.2Eu phosphors were assembled with a 365 nm LED chip to fabricate a WLED device that showed excellent white-colored coordinates (0.345, 0.358) and a high Ra value of 90.1 under a 300 mA current.