ABSTRACT Site-dependent Eu3+ photoluminescence (PL) was examined utilizing the structural difference of two Eu3+ doped alkaline earth lanthanum tantalates with the B-site-ordered double perovskite-type structure (AA’)[BB’]O6, viz. (CaLa1−xEux)[CaTa]O6 (CLTO:Eu3+) and (Ba2)[La1−xEuxTa]O6 (BLTO:Eu3+) (x = 0.01, 0.10). The locations of the Eu3+ ions were experimentally determined by X-ray absorption near edge structure of the Eu LIII edge and confirmed to be A sites in CLTO:Eu3+ and B sites in BLTO:Eu3+ as expected from the nominal compositions. Intense charge transfer (CT) excitation bands were observed in the UV region in the PL excitation spectra of both materials. Because of the shorter bond lengths and larger electronic repulsion at B sites than A sites, the CT excitation band of Eu3+ at B sites in BLTO:Eu3+ was blue-shifted compared to that of Eu3+ at A sites in CLTO:Eu3+. By UV excitation in the CT bands, both materials showed red luminescence. However, due to the difference in the site symmetry of A and B sites, the Eu3+ emission was mainly derived from the 5D0 – 7F2 transitions in CLTO:Eu3+ and from the 5D0 – 7F1 transitions in BLTO:Eu3+ in relation with Eu3+ at A and B sites, respectively. The lifetimes of the emission were also dependent on the Eu3+ sites resulting in the longer lifetimes of Eu3+ ions at B sites than those at A sites.

中文翻译：

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双钙钛矿型碱土钽酸盐中的位点相关 Eu3+ 光致发光

摘要 利用两种 Eu3+ 掺杂的碱土金属钽酸盐与 B 位有序双钙钛矿型结构 (AA')[BB']O6 的结构差异，研究了位点相关的 Eu3+ 光致发光 (PL)，即。(CaLa1−xEux)[CaTa]O6 (CLTO:Eu3+) 和 (Ba2)[La1−xEuxTa]O6 (BLTO:Eu3+) (x = 0.01, 0.10)。Eu3+ 离子的位置通过 Eu LIII 边缘的近边缘结构的 X 射线吸收实验确定，并证实为 CLTO:Eu3+ 中的 A 位点和 BLTO:Eu3+ 中的 B 位点，如标称组成所预期的那样。在两种材料的 PL 激发光谱中，在紫外区观察到强电荷转移 (CT) 激发带。由于 B 位点比 A 位点的键长更短且电子排斥力更大，因此 BLTO 中 B 位点的 Eu3+ 的 CT 激发带：与 CLTO:Eu3+ 中 A 位点的 Eu3+ 相比，Eu3+ 发生蓝移。通过 CT 波段的紫外激发，两种材料均显示红色发光。然而，由于 A 和 B 位点对称性的不同，Eu3+ 发射主要来源于 CLTO:Eu3+ 中的 5D0-7F2 跃迁和 BLTO:Eu3+ 中与 Eu3+ 在 A 和B站点，分别。发射的寿命也取决于 Eu3+ 位点，导致 B 位点的 Eu3+ 离子的寿命比 A 位点长。Eu3+ 分别与 A 和 B 位点的 Eu3+ 相关。发射的寿命也取决于 Eu3+ 位点，导致 B 位点的 Eu3+ 离子的寿命比 A 位点长。Eu3+ 分别与 A 和 B 位点的 Eu3+ 相关。发射的寿命也取决于 Eu3+ 位点，导致 B 位点的 Eu3+ 离子的寿命比 A 位点长。