Abstract：
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 Y2(Ti1-xHfx)2O7:Eu phosphors were prepared by adjusting the HfO2 and Eu3+ concentrations. In particular, white Y2(Ti0.8Hf0.2)2O7: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 Eu2+ and Eu3+ emissions and HfO2 defect emission. The formation of Eu2+ ions was caused by the introduction of HfO2, which causes self-reduction of Eu3+ ions but does not require additional reducing agents. The white Y2(Ti0.8Hf0.2)2O7:Eu phosphors exhibit low color shifting at high temperature, which is very important for LED applications. The chromaticity shift of the Y2(Ti0.8Hf0.2)2O7:0.2Eu phosphor is 2.83 × 10-2 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. Y2 (Ti0.8Hf0.2)2O7:0.2Eu 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.
摘要：
可在近紫外光中激活的白色磷光体的开发在LED照明领域中非常重要。在这项工作中,通过调节HfO2和Eu3+浓度制备了一系列颜色可调的Y2(Ti1-xHfx)2O7:Eu荧光粉。特别是,成功地合成了白色Y2(Ti0.8Hf0.2)2O7:Eu磷光体,并且在用340nmUV光激发时发射覆盖整个可见光区域的宽带。白色带状材料由Eu2+和Eu3+发射和HfO2缺陷发射组成。Eu2+离子的形成是由HfO2的引入引起的,其引起Eu3+离子的自还原,但不需要额外的还原剂。白色Y2(Ti0.8Hf0.2)2O7:Eu荧光粉在高温下表现出低的色移，这对LED应用非常重要。Y2（Ti0.8Hf0.2）2O7：0.2Eu荧光粉在503K时的色度偏移为2.83×10-2，在相同温度下，仅为商业三色白色荧光粉的54.8%。Ra值没有随着温度的升高而显着降低，在383K时达到90.2。Y2（Ti0.8Hf0.2）2O7：0.2Eu磷光体与365nm的LED芯片组装在一起，以制造WLED器件，该器件在300mA电流下显示出优异的白色坐标（0.345，0.358）和90.1的高Ra值。
