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arXiv · 1701.08248

Controlling disorder in the ZnGa$_2$O$_4$:Cr$^{3+}$ persistent phosphor by Mg$^{2+}$ substitution

Neelima Basavaraju·Kaustubh R. Priolkar·Aurélie Bessière·Suchinder K. Sharma·Didier Gourier·Laurent Binet·Bruno Viana·Shuichi Emura
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Abstract

We have studied in this work the effect of increasing structural disorder on the persistent luminescence of Cr$^{3+}$ doped zinc gallate spinel. This disorder was introduced by progressive substitution of Zn$^{2+}$ by Mg$^{2+}$ 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 Mg/Zn substitution decreases the number of Cr$^{3+}$ in undistorted sites, and increases the number of Cr$^{3+}$ with neighbouring antisite defects and with neighbouring Cr$^{3+}$ ions (referred 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$^{3+}$ spectra with three types of Cr$^{3+}$ 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$^{3+}$ ions.

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Neelima Basavaraju, Kaustubh R. Priolkar, Aurélie Bessière, Suchinder K. Sharma, Didier Gourier, Laurent Binet, Bruno Viana, Shuichi Emura. 2017-01-28. Controlling disorder in the ZnGa$_2$O$_4$:Cr$^{3+}$ persistent phosphor by Mg$^{2+}$ substitution. https://doi.org/10.1039/c6cp06443d

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