Olchowka J, Mentré O, Kabbour H, Colmont M, Adlung M, Suta M, Wickleder C
University of Siegen, Department Chemistry/Biology, Faculty of Science and Technology, 57068, Siegen, Germany.
Univ. Lille, CNRS, Centrale Lille, ENSCL, Univ. Artois, UMR 8181-UCCS-Unité de Catalyse et Chimie du Solide, 59000, Lille, France.
Chemistry. 2017 Nov 7;23(62):15694-15703. doi: 10.1002/chem.201702373. Epub 2017 Oct 16.
Luminescence properties of the Bi(M,M') PO (M=Mg, Zn, Cd) series have been rationalized as a function of the M element using optical spectroscopy, as well as empirical and first principles calculations. The latter yielded indirect band gaps for all compounds with energies between 2.64 and 3.62 eV, whereas luminescence measurements exhibit bright warm white emission luminescence even at room temperature assigned to Bi transitions with, for example, 22.8 % quantum yield for M=Mg. The energies of the excitation maxima are shifted with the covalent character of the Bi-O bond by inductive effects of the neighboring M-O bonds. This is discussed on the basis of empirical and electronic structure calculations. Strikingly, in all the investigated compounds, an excitation process occurring at energies higher than the band gaps is observed, which seems to be intrinsic to the s →sp electronic transitions of the Bi ions. Concerning the emission process, a direct correlation between the lone pair (LP) activity and the emission energy upon change of the lattice parameters was established governing the LP stereo-activity in the BiMg Cd PO system. As a result, the possibility for tunable optical properties appears realistic in the Bi O -MO-X O (X=P, V, As, etc.) systems taking into account the diversity of reported or novel crystal structures that can be designed using well-established rules of crystal chemistry.
利用光谱学以及经验计算和第一性原理计算，对Bi(M,M')PO（M = Mg、Zn、Cd）系列的发光特性与M元素的函数关系进行了合理分析。后者得出所有化合物的间接带隙能量在2.64至3.62 eV之间，而发光测量显示即使在室温下也有明亮的暖白色发射发光，这归因于Bi跃迁，例如对于M = Mg，量子产率为22.8%。激发最大值的能量通过相邻M - O键的诱导效应随Bi - O键的共价特性而移动。这是在经验计算和电子结构计算的基础上进行讨论的。引人注目的是，在所有研究的化合物中，都观察到在高于带隙的能量处发生的激发过程，这似乎是Bi离子s→sp电子跃迁所固有的。关于发射过程，在BiMgCdPO系统中，建立了孤对（LP）活性与晶格参数变化时发射能量之间的直接相关性，从而控制了LP立体活性。因此，考虑到可以使用成熟的晶体化学规则设计的已报道或新型晶体结构的多样性，在Bi₂O₃ - MO - X₂O₃（X = P、V、As等）系统中实现可调光学特性的可能性似乎是现实的。
