Site-Dependent Eu3+ Photoluminescence in Double Perovskite-Type Alkaline Earth Lanthanum Tantalates
Site-Dependent Eu3+ Photoluminescence in Double Perovskite-Type Alkaline Earth Lanthanum Tantalates
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DOI：
10.1016/j.jlumin.2020.117683
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发表时间：
2021-01
影响因子：
3.6
通讯作者：
Kazushige Ueda;T. Yoshino;Y. Shimizu;T. Honma;F. Massuyeau;S. Jobic
中科院分区：
文献类型：
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作者：
Kazushige Ueda;T. Yoshino;Y. Shimizu;T. Honma;F. Massuyeau;S. Jobic
利用两种具有B位有序双钙钛矿型结构（AA '）[BB'] O 6的Eu 3+掺杂碱土金属钽酸镧的结构差异，即（CaLa 1 −xEux）[CaTa] O 6（CLTO：Eu 3+）和（Ba 2）[La 1 −xEuxTa] O 6（BLTO：Eu 3+）（x= 0.01，0.10），研究了Eu 3+的位置相关光致发光（PL）。Eu 3+离子的位置通过Eu LIIIedge的X射线吸收近边结构实验确定，并确认为CLTO：Eu 3+中的A位点和BLTO：Eu 3+中的B位点，如从标称组成所预期的。强烈的电荷转移（CT）激发带中观察到的两种材料的PL激发光谱中的UV区域。由于B位比A位的键长短，电子排斥力大，故BLTO：Eu 3+中Eu 3+在B位的CT激发带比CLTO：Eu 3+中Eu 3+在A位的CT激发带蓝移。通过紫外激发在CT波段，这两种材料显示红色发光。但由于A、B位对称性的不同，Eu 3+的发射主要来自CLTO：Eu 3+的5D 0 - 7 F2跃迁，而BLTO：Eu 3+的5D 0 - 7 F1跃迁分别与A、B位的Eu 3+有关。发光寿命也依赖于Eu 3+的位置，导致Eu 3+离子在B位的寿命比在A位的寿命长。
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 LIIIedge 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 the5D0–7F2transitions in CLTO:Eu3+and from the5D0–7F1transitions 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.