Abstract High-efficiency red-emitting phosphors are required to fabricate high-performance white light-emitting diodes (LEDs). Herein, the novel highly efficient Eu3+-activated Ca2GdSbO6 double-perovskite red phosphors with good thermal stability toward warm-white LEDs were reported. A series of Ca2Gd(1-x)EuxSbO6 red phosphors with different Eu3+ doping concentrations (x = 0.2, 0.3, 0.4, 0.5, 0.6, 0.7 and 0.8) were synthesized by using high-temperature solid-state reaction method. Under the excitation of 396 nm near-ultraviolet light, these Ca2Gd(1-x)EuxSbO6 phosphors showed intense red emissions peaking at 612 nm due to the 5D0→7F2 transition of Eu3+ ions. The strongest luminescence intensity reached when Eu3+ doping concentration was x = 0.5, and the critical distance between Eu3+ activators was calculated to be 7.97 A. The concentration quenching mechanism was due to the dipole-dipole interaction of Eu3+ ions. The CIE color coordinates of the optimal Ca2Gd0.5Eu0.5SbO6 phosphors were determined to be (0.6629, 0.3367), and the corresponding color purity reached about 94.9%. Importantly, the Ca2Gd0.5Eu0.5SbO6 phosphors revealed outstanding internal quantum efficiency of 73% and good thermal stability. The emission intensity of Ca2Gd0.5Eu0.5SbO6 phosphors at 423 K still remained about 73% of its initial value at 303 K. Finally, a prototype white LED device was fabricated by coating the phosphor blend of commercial blue-emitting BaMgAl10O17:Eu2+, green-emitting (Ba, Sr)2SiO4:Eu2+ and our as-prepared red-emitting Ca2Gd0.5Eu0.5SbO6 on a 395 nm LED chip. Under 20 mA driven current, the device showed bright warm-white light with CIE color coordinates of (0.3888, 0.3943), correlated color temperature of 3911 K, and color rendering index of 88.4. The results demonstrated that the developed novel red-emitting Ca2Gd0.5Eu0.5SbO6 phosphors could be used as potential color converters in white LEDs.

中文翻译：

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用于白光 LED 的具有高色纯度的新型高发光双钙钛矿 Ca2GdSbO6:Eu3+ 红色荧光粉：合成、晶体结构和光致发光特性

摘要 制造高性能的白光发光二极管 (LED) 需要高效的红色荧光粉。本文报道了新型高效 Eu3+ 激活的 Ca2GdSbO6 双钙钛矿红色荧光粉，对暖白光 LED 具有良好的热稳定性。采用高温固相反应法合成了一系列不同Eu3+掺杂浓度（x=0.2、0.3、0.4、0.5、0.6、0.7和0.8）的Ca2Gd(1-x)EuxSbO6红色荧光粉。在 396 nm 近紫外光的激发下，由于 Eu3+ 离子的 5D0→7F2 跃迁，这些 Ca2Gd(1-x)EuxSbO6 荧光粉在 612 nm 处显示出强烈的红色发射峰。当 Eu3+ 掺杂浓度为 x = 0.5 时达到最强发光强度，计算 Eu3+ 活化剂之间的临界距离为 7.97 A。浓度猝灭机制是由于 Eu3+ 离子的偶极-偶极相互作用。确定最佳Ca2Gd0.5Eu0.5SbO6荧光粉的CIE色坐标为(0.6629,0.3367)，相应的色纯度达到94.9%左右。重要的是，Ca2Gd0.5Eu0.5SbO6 荧光粉显示出 73% 的出色内量子效率和良好的热稳定性。Ca2Gd0.5Eu0.5SbO6 荧光粉在 423 K 下的发射强度仍保持其初始值在 303 K 时的约 73%。 最后，通过涂覆商用蓝色发光 BaMgAl10O17:Eu2+ 的荧光粉混合物制造了原型白色 LED 器件，绿色-在 395 nm LED 芯片上发射 (Ba, Sr)2SiO4:Eu2+ 和我们制备的红色发射 Ca2Gd0.5Eu0.5SbO6。在 20 mA 驱动电流下，器件呈现明亮的暖白光，CIE 色坐标为 (0.3888, 0.3943)，相关色温为 3911 K，显色指数为 88.4。结果表明，开发的新型红色发光 Ca2Gd0.5Eu0.5SbO6 荧光粉可用作白光 LED 中的潜在颜色转换器。