Optical properties of Cr3+ in MgAl2O4 spinel

Abstract

Absorption and luminescence spectra of Cr3+ in the disordered synthetic MgAl2O4 spinel are reported. The splitting of the 4T2g absorption band and the excitation wavelength dependence of luminescence indicate the presence of two different Cr3+ sites in this crystal. An excitation of Cr3+ in site A leads to broad band fluorescence whereas an excitation of the B site leads to the narrow band luminescence similar to that of the natural spinel. The nature of luminescence is discussed.