CaTi4(PO4)6:xEu3+ phosphors are successfully synthesized under air condition by high-temperature solid-state method. The crystal structure, morphology, energy spectrum, atomic percentage, elemental mapping, and luminescence properties are investigated, respectively. Monitored at 594 nm, the excitation spectral bands of CaTi4(PO4)6:Eu3+ phosphor in the range of 210–550 nm are assigned to the O2−–Eu3+ charge transfer band (CTB) and the 7F0 → 5H3, 5L7, 5L6, 5D1, 5D2, 5D3, and 5D4 transitions of Eu3+ ion. With excitation at 394 nm, CaTi4(PO4)6:Eu3+ phosphor emits orange-red light with the chromaticity coordinates (0.548, 452), and the emission spectral bands in the region from 575 to 720 nm are attributed to the 5D0 → 7F1, 7F2, 7F3, and 7F4 transitions of Eu3+ ion. The optimal doping concentration of Eu3+ ion is ~ 8 mol%. The lifetime of CaTi4(PO4)6:Eu3+ phosphors decreases from 1.87 to 0.97 ms with increasing Eu3+ concentrations from 1 to 10 mol%. CaTi4(PO4)6:Eu3+ phosphor has a good thermal stability. The experimental results indicate that CaTi4(PO4)6:Eu3+ phosphor has an application prospect in white light-emitting diodes (LEDs) based on the near ultraviolet (~ 394 nm) LED chip.

中文翻译：

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用于白光 LED 的橙红色发光 CaTi4(PO4)6:Eu3+ 磷光体：合成和发光特性

采用高温固相法在空气条件下成功合成了CaTi4(PO4)6:xEu3+荧光粉。分别研究了晶体结构、形貌、能谱、原子百分比、元素映射和发光特性。在 594 nm 处监测，CaTi4(PO4)6:Eu3+ 磷光体在 210–550 nm 范围内的激发光谱带被分配到 O2−–Eu3+ 电荷转移带 (CTB) 和 7F0 → 5H3、5L7、5L6、 Eu3+ 离子的 5D1、5D2、5D3 和 5D4 跃迁。在 394 nm 激发下，CaTi4(PO4)6:Eu3+ 荧光粉发出橙红色光，色度坐标为 (0.548, 452)，575 至 720 nm 区域的发射光谱带归因于 5D0 → 7F1， Eu3+ 离子的 7F2、7F3 和 7F4 跃迁。Eu3+ 离子的最佳掺杂浓度为~8 mol%。CaTi4(PO4)6的寿命：随着 Eu3+ 浓度从 1 mol% 增加到 10 mol%，Eu3+ 磷光体从 1.87 ms 减少到 0.97 ms。CaTi4(PO4)6:Eu3+荧光粉具有良好的热稳定性。实验结果表明，CaTi4(PO4)6:Eu3+ 荧光粉在基于近紫外 (~394 nm) LED 芯片的白光发光二极管 (LED) 中具有应用前景。