title: Controlling disorder in the ZnGa2O4:Cr3+persistent phosphor by Mg2+substitution.
abstract: We have studied in this work the effect of increasing structural disorder on the persistent luminescence of a Cr3+doped zinc gallate spinel. This disorder was introduced by progressive substitution of Zn2+by Mg2+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 Cr3+in undistorted sites and increases the number of Cr3+with neighbouring antisite defects and with neighbouring Cr3+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 Cr3+spectra with three types of Cr3+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 Cr3+ions.
authors.affiliation: Department of Physics, Goa University, Taleigao plateau, Goa 403206, India. krp@unigoa.ac.in.
authors.forename: Neelima
authors.initials: N
authors.lastname: Basavaraju
authors.affiliation: Department of Physics, Goa University, Taleigao plateau, Goa 403206, India. krp@unigoa.ac.in.
authors.forename: Kaustubh R
authors.initials: KR
authors.lastname: Priolkar
authors.affiliation: PSL Research University, Chimie ParisTech - CNRS, Institut de Recherche de Chimie Paris, 75005, Paris, France.
authors.forename: Aurélie
authors.initials: A
authors.lastname: Bessière
authors.affiliation: PSL Research University, Chimie ParisTech - CNRS, Institut de Recherche de Chimie Paris, 75005, Paris, France.
authors.forename: Suchinder K
authors.initials: SK
authors.lastname: Sharma
authors.affiliation: PSL Research University, Chimie ParisTech - CNRS, Institut de Recherche de Chimie Paris, 75005, Paris, France.
authors.forename: Didier
authors.initials: D
authors.lastname: Gourier
authors.affiliation: PSL Research University, Chimie ParisTech - CNRS, Institut de Recherche de Chimie Paris, 75005, Paris, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Binet
authors.affiliation: PSL Research University, Chimie ParisTech - CNRS, Institut de Recherche de Chimie Paris, 75005, Paris, France.
authors.forename: Bruno
authors.initials: B
authors.lastname: Viana
authors.affiliation: Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan.
authors.forename: Shuichi
authors.initials: S
authors.lastname: Emura