Eu2+/Eu3+-emission-ratio-tunable CaZr(PO4)2:Eu phosphors synthesized in air atmosphere for potential white light-emitting deep UV LEDs
Eu2+/Eu3+-emission-ratio-tunable CaZr(PO4)2:Eu phosphors synthesized in air atmosphere for potential white light-emitting deep UV LEDs
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Eu2 /Eu3 -发射比可调的 CaZr(PO4)2:Eu 荧光粉在空气气氛中合成，用于潜在的白光发射深紫外 LED
DOI：
10.1039/c3tc31798f
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发表时间：
2014-01-01
影响因子：
6.4
通讯作者：
Sun, Xin-Yuan
中科院分区：
文献类型：
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作者：
Zhang, Jun-Cheng;Long, Yun-Ze;Sun, Xin-Yuan
首次采用两步固相反应法在空气气氛中合成了混合价态Eu掺杂CaZr（PO 4）2。在第二步合成中，利用NH_4H_2PO_4和第一步产物CaZrO_3：Eu ~（3+）在空气气氛中还原为Eu ~（2+），合成了CaZr（PO_4）_2：Eu。这种还原机制是由电荷补偿模型解释的。发光测试表明，在200-350 nm紫外光激发下，Eu 2+具有宽的蓝绿色荧光，Eu 3+具有尖锐的橙红色发射。随着烧结时间的延长，Eu 3+逐渐还原为Eu 2+，实现了覆盖整个可见光谱的可调谐白色发光。在247 nm处激发的最佳白色发光色坐标为（0.322，0.305），相关色温为6243 K，具有良好的热稳定性。此外，在CaZr（PO 4）2：Eu中还发现了Eu ~（2+）向Eu ~（3+）的能量转移。我们对CaZr（PO 4）2：Eu的研究为新型白色发光二极管（W-LED）荧光粉的设计和制备提供了理论依据。
Mixed-valence Eu-doped CaZr(PO4)2 was prepared in air atmosphere by a two-step solid-state reaction for the first time. The reduction of Eu3+ to Eu2+ in air atmosphere was observed in the second synthesis step via the use of NH4H2PO4 and the first-step product CaZrO3:Eu3+ to synthesize CaZr(PO4)2:Eu, which strengthens the evidence linking the tetrahedral anion groups PO4 with the Eu reduction. This reduction mechanism is explained by a charge compensation model. The luminescence measurements indicate that the obtained phosphors exhibit a broad bluish-green fluorescence of Eu2+ and a sharp orange-red emission of Eu3+ on 200–350 nm ultraviolet (UV) excitations. A tunable white luminescence covering the whole visible spectrum is realized based on the gradual reduction of Eu3+ to Eu2+ with increasing the sintering time. The optimal white luminescence excited at 247 nm presents the CIE color coordinates of (0.322, 0.305), a correlated color temperature of 6243 K, and a good thermal stability. Furthermore, energy transfer from Eu2+ to Eu3+ is found in CaZr(PO4)2:Eu. Our investigation of CaZr(PO4)2:Eu may provide a practical basis to design and fabricate novel phosphors for white light-emitting diodes (W-LEDs).