Local coordination, electronic structure, and thermal quenching of Ce3+ in isostructural Sr2 GdAlO5 and Sr3 AlO4 F phosphors
Local coordination, electronic structure, and thermal quenching of Ce3+ in isostructural Sr2 GdAlO5 and Sr3 AlO4 F phosphors
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DOI：
10.1111/jace.15985
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发表时间：
2018-08
影响因子：
3.9
通讯作者：
Haipeng Ji;Jian Xu;Kazuki Asami;J. Ueda;M. Brik;S. Tanabe
中科院分区：
文献类型：
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作者：
Haipeng Ji;Jian Xu;Kazuki Asami;J. Ueda;M. Brik;S. Tanabe
Sr 2GdAlO 5：Ce和Sr 3AlO 4F：Ce是同构磷光体，其中Ce 3 +4f-5d 1跃迁可以由能量低于3.1eV的光子有效激发。在此，我们分析了Ce ~（3+）局域配位的晶体化学，比较了它们的热猝灭行为，并构建了Ce ~（3+）在其中的电子结构。Rietveld细化两个占位模型表明，Gd 3+只占据Sr 2GdAlO 5的8h网站，这提供了一个提示掺杂剂Ce 3+在这个网站上的优先占位。Ce 8的大晶场分裂主要是由于8h位以相对短的Sr/Gd-O键合到两个氧上并形成经历大畸变的准正方形反棱柱。Sr 3AlO 4F中的Ce 3 +5d-4荧光比Sr 2GdAlO 5中的热猝灭稳定得多，这由温度依赖的发光强度和发光衰减研究证明。计算了O2−-Eu 3 +/2+和O2−-Ce 4 +/3+电荷转移的能量和带隙，并构建了Ce 3+的电子结构。真空参考结合能（VRBE）图表明，在Sr 3AlO 4F中，Ce 3 + 5d 1能级与导带底之间存在较大的能垒Δ EdC，用热电离模型解释了Sr 3AlO 4F较高的热猝灭温度。
Sr2GdAlO5:Ce and Sr3AlO4F:Ce are isostructural phosphors in which the Ce3+4f‐5d1transition can be efficiently excited by a photon with energy lower than 3.1 eV. Herein, we analyze the crystal chemistry of the Ce3+local coordination, compare the thermal quenching behavior and construct the electronic structure of Ce3+in them. The Rietveld refinement on two occupancy models suggests that Gd3+only occupies the 8hsite in Sr2GdAlO5; this provides a hint on the preferred occupancy of dopant Ce3+in this site. The large crystal filed splitting of Ce8his mainly due to the fact that the 8hsite is bonded to two oxygen with relatively shortdSr/Gd‐Oand forms a quasi‐square antiprism which experiences a large distortion. The Ce3+5d‐4fluminescence in Sr3AlO4F is much more stable against thermal quenching than that in Sr2GdAlO5, as evidenced by the temperature‐dependent luminescence intensity and luminescence decay studies. The energy of the O2−‐Eu3+/2+and O2−‐Ce4+/3+charge transfer as well as bandgap were estimated and the electronic structure of Ce3+were constructed. A larger energy barrier ΔEdCbetween the Ce3+5d1level and the conduction band bottom in Sr3AlO4F is seen from the Vacuum Referred Binding Energy (VRBE) diagrams which explains the higher thermal quenching temperature by thermal ionization model.