Abstract The Dy3+, Tm3+ ions activated, and Dy3+/Tm3+ ions co-activated Na3Gd(PO4)2 phosphors were synthesized by the citrate-gel based combustion technique. The structural properties of as-synthesized phosphors were studied through X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The influence of Tm3+ concentration on the fluorescence properties of Na3Gd(PO4)2:Dy3+/Tm3+ phosphors were systematically investigated under near-UV light irradiation of 359 and 352 nm. The energy transfer efficiency (ηET) of as-prepared phosphors increases gradually from 17 to 42%, and the critical distance (Rc) between Dy3+ and Tm3+ ions is calculated to be 4.76 A. For better understanding the energy transfer mechanism (ET:Dy3+ →Tm3+), the decay curves were utilized on the basis of Dexter's energy transfer formula and Reisfeld's approximation. More importantly, the obtained CIE color coordinates of Na3Gd(PO4)2:Dy3+/Tm3+ phosphors located at blue-white region under near-UV light irradiation. The results demonstrate the promising application of Na3Gd(PO4)2:Dy3+/Tm3+ phosphor for near-UV white LEDs.

中文翻译：

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用于白光 LED 的 Dy3+/Tm3+:Na3Gd(PO4)2 纳米磷光体中近紫外激发的高效蓝白色发光

摘要 采用柠檬酸-凝胶燃烧技术合成了Dy3+、Tm3+离子激活和Dy3+/Tm3+离子共激活Na3Gd(PO4)2荧光粉。通过 X 射线衍射 (XRD) 和傅里叶变换红外光谱 (FT-IR) 研究了合成的磷光体的结构特性。在 359 和 352 nm 的近紫外光照射下，系统研究了 Tm3+ 浓度对 Na3Gd(PO4)2:Dy3+/Tm3+ 荧光粉荧光性质的影响。所制备的荧光粉的能量转移效率 (ηET) 从 17% 逐渐增加到 42%，计算 Dy3+ 和 Tm3+ 离子之间的临界距离 (Rc) 为 4.76 A。 为了更好地理解能量转移机制 (ET:Dy3+ →Tm3+)，衰减曲线是基于 Dexter 的能量转移公式和 Reisfeld' s 近似值。更重要的是，获得了在近紫外光照射下位于蓝白色区域的 Na3Gd(PO4)2:Dy3+/Tm3+ 荧光粉的 CIE 颜色坐标。结果证明了 Na3Gd(PO4)2:Dy3+/Tm3+ 荧光粉在近紫外白光 LED 中的应用前景。