Luminescence and photoconductivity in magnesium aluminum spinel

Abstract

Ultraviolet-light excitation of thermochemically reduced ${\mathrm{MgAl}}_2$ ${\mathrm{O}}_4$ single crystals below room temperature produces a luminescence band with a peak at 2.69 eV. The excitation spectrum of the 2.69-eV band coincides with the broad F-center absorption band at 5.30 eV. The 2.69-eV band is also emitted in uv-stimulated glow peaks which occur at 95 and 265 K. A photoconductivity maximum is observed at 5.39 eV at temperatures above 160 K, but the band is readily bleached by uv light.