Tuning of Photoluminescence and Local Structures of Substituted Cations in xSr2Ca(PO4)2–(1 – x)Ca10Li(PO4)7:Eu2+ Phosphors

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• 作者：Mingyue Chen ; Zhiguo XiaMaxim S. Molokeev ; Ting WangQuanlin Liu
• 刊名：Chemistry of Materials
• 出版年：2017
• 出版时间：February 14, 2017
• 年：2017
• 卷：29
• 期：3
• 页码：1430-1438
• 全文大小：620K
• ISSN：1520-5002

文摘

Local structure modification in solid solution is an essential part of photoluminescence tuning of rare earth doped solid state phosphors. Herein we report a new solid solution phosphor of Eu<sup>2+sup>-doped xSr<sub>2sub>Ca(PO<sub>4sub>)<sub>2sub>–(1 – x)Ca<sub>10sub>Li(PO<sub>4sub>)<sub>7sub> (0 ≤ x ≤ 1), which share the same β-Ca<sub>3sub>(PO<sub>4sub>)<sub>2sub> type structure in the full composition range. Depending on the x parameter variation in xSr<sub>2sub>Ca(PO<sub>4sub>)<sub>2sub>–(1 – x)Ca<sub>10sub>Li(PO<sub>4sub>)<sub>7sub>:Eu<sup>2+sup>, the vacancies generated in the M(4) site enable the nonlinear variation of cell parameters and volume, and this increases the magnitude of M(4)O<sub>6sub> polyhedra distortion. The local structure modulation around the Eu<sup>2+sup> ions causes different luminescent behaviors of the two-peak emission and induces the photoluminescence tuning. The shift of the emission peaks in the solid solution phosphors with different compositions has been discussed. It remains invariable at x ≤ 0.5, but the red-shift is observed at x > 0.5 which is attributed to combined effect of the crystal field splitting, Stokes shift, and energy transfer between Eu<sup>2+sup> ions. The temperature-dependent luminescence measurements are also performed, and it is shown that the photoionization process is responsible for the quenching effect.