Pulse Cathodoluminescence of the Impurity Centers in Ceramics Based on the MgAl2O4 Spinel

Abstract

The spectral and luminescence decay kinetics of magnesium aluminate spinel ceramics prepared by spark plasma sintering (SPS) and the starting nanopowders were studied. It was demonstrated that two types of luminescence in spinel ceramics can be observed after pulse e-beam excitation. The first type is due to intrinsic defects, and the second type due to Cr3+ and Mn2+ ions. It was shown that the luminescence decay kinetics for Cr3+ and Mn2+ impurity ions can be approximated by the sum of two exponents. The decay times for the Cr3+ ion are 35 and 409 ns, for the Mn2+ ion are 29 and 340 ns. High-temperature exposure during SPS synthesis does not lead to a change in the nearest surroundings of impurity ions. In the luminescence spectra of ceramic and powder samples the intensity ratio changes of intrinsic and impurity centers is associated with strong diffuse scattering of light for spinel nanopowders.