Basavaraju Neelima, Priolkar Kaustubh R, Bessière Aurélie, Sharma Suchinder K, Gourier Didier, Binet Laurent, Viana Bruno, Emura Shuichi
Department of Physics, Goa University, Taleigao plateau, Goa 403206, India.
PSL Research University, Chimie ParisTech - CNRS, Institut de Recherche de Chimie Paris, 75005, Paris, France.
Phys Chem Chem Phys. 2017 Jan 4;19(2):1369-1377. doi: 10.1039/c6cp06443d.
We have studied in this work the effect of increasing structural disorder on the persistent luminescence of a Cr doped zinc gallate spinel. This disorder was introduced by progressive substitution of Zn by Mg ions, and was studied by photoluminescence, X-ray diffraction, extended X-ray absorption fine structure (EXAFS), X-ray absorption near edge structure (XANES) and electron paramagnetic resonance (EPR) spectroscopy. It was found that increasing the Mg/Zn substitution decreases the number of Cr in undistorted sites and increases the number of Cr with neighbouring antisite defects and with neighbouring Cr ions (referred to as Cr clusters), which in turn decreases the intensity of persistent luminescence. Both XANES and EPR spectra could be simulated by a linear combination of Cr spectra with three types of Cr environments. The increasing disorder was found to be correlated with a decrease of the average Cr-O bond length and a decrease of crystal field strength experienced by Cr ions.
在这项工作中，我们研究了结构无序度增加对掺铬锌镓酸盐尖晶石持续发光的影响。这种无序是通过用镁离子逐步取代锌引入的，并通过光致发光、X射线衍射、扩展X射线吸收精细结构（EXAFS）、X射线吸收近边结构（XANES）和电子顺磁共振（EPR）光谱进行研究。结果发现，增加镁/锌取代会减少未畸变位点中铬的数量，并增加具有相邻反位缺陷和相邻铬离子（称为铬簇）的铬的数量，这反过来又会降低持续发光的强度。XANES和EPR光谱都可以通过具有三种类型铬环境的铬光谱的线性组合来模拟。发现无序度的增加与平均Cr-O键长的减小以及铬离子所经历的晶体场强度的减小相关。
