Site occupation and photoluminescence properties of Ce3+ in Sr4Ca4La2 (PO4)(6)O-2: Experiments and ab initio calculations
Site occupation and photoluminescence properties of Ce3+ in Sr4Ca4La2 (PO4)(6)O-2: Experiments and ab initio calculations
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Ce3 在 Sr4Ca4La2 (PO4)(6)O-2 中的位点占据和光致发光性质：实验和从头算
DOI：
10.1016/j.optmat.2017.01.033
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发表时间：
2017
影响因子：
3.9
通讯作者：
Liang Hongbin
中科院分区：
文献类型：
--
作者：
Zhou Rongfu;Ning Lixin;Zhou Weijie;Lin Litian;Shi Rui;Liang Hongbin
采用传统的固相反应法制备了掺Ce的氧化物磷灰石荧光粉：Sr4Ca4La2(PO4)6O2：Ce3+。X-射线衍射分析表明，六方相结构的特点是：在9配位的阳离子4f位上随机分布着锶和钙原子，在7配位的阳离子6h位上随机分布着锶、钙和镧原子。研究了Ce掺杂样品在真空-紫外光(VUV)-紫外光(UV)范围内的低温光致发光特性。根据发射光谱、激发光谱和发光衰减行为的分析，确定了Ce3+的三种主要占位类型。Ce~(3+)在七配位La(6~h)上占据主导地位，这是由基于波函数的Ce~(3+)4f、→和5d自旋轨道跃迁能团簇计算所支持的。强调了未与P5+键合的配位氧离子在CeLa(6h)3+5d质心位移中的作用。结合Ce3+的配位结构，研究和讨论了5d发光的热稳定性和掺杂浓度依赖性。
Cerium-doped oxyapatite phosphors, Sr4Ca4La2(PO4)6O2: Ce3+, are prepared by a traditional solid-state reaction method. X-ray diffraction (XRD) refinement reveals that the hexagonal Sr4Ca4La2(PO4)6O2structure is characterized by a random distribution of Sr and Ca atoms on the nine-coordinated cationic 4f sites and of Sr, Ca, and La atoms on the seven-coordinated cationic 6 h sites. Photoluminescence properties of Ce-doped samples are then studied with excitation energies in the vacuum-ultraviolet (VUV) to ultraviolet (UV) range at low temperature. Three main types of occupation sites for Ce3+are identified based on analysis of emission and excitation spectra and of luminescence decay behaviors. The Ce3+occupation on the seven-coordinated La (6 h) site is found to be dominant, which is supported by wave function-based CASSCF/CASPT2 embedded cluster calculations on Ce3+4f → 5d transition energies at the spin-orbit level. The role of the coordinated oxygen ion that is not bonded with P5+in the 5d centroid shift of CeLa(6h)3+is emphasized. The thermal stability and doping concentration dependence of the 5d luminescence are also investigated and discussed in association with the coordination structures of Ce3+.