Two non-first-order kinetic peaks at about 350 and 500 K appear in the thermoluminescence (TL) spectra of single-crystal and polycrystalline MgAl2O4 irradiated with ionizing radiation at room temperature. Among others, emission from Cr3+ and Mn2+ ions are observed. TL measurements at different wavelengths indicate that the emitting centers have different recombination probabilities. Thermallystimulated-current and thermoelectric-power measurements, together with results on the TL excitation spectra with ultraviolet radiation, indicate that both processes are due to thermally released electrons from traps. The V centers also act as recombination centers leading to a complex emission band at around 4.9 eV. Experimental results and numerical simulations based on a recently proposed mathematical model suggest that the massive presence of lattice defects, as a result of the antisite disorder and the nonstoichiometry of synthetic spinel crystals, may have a strong influence on electron-trapping and -detrapping processes, leading to complex-kinetics TL phenomena. © 1991 The American Physical Society

We are indebted to Dr. R. Heidinger (Kernforschungzentrum Karlsruhe, GFR) for the polycrystalline spinel sample supply, to Dr. E. R. Hodg son (CIEMAT, Madrid) for performing the TSC measurements, and to Dr. F. J. Lopez (Universidad Autonoma de Madrid, Spain) for his assistance in EPR measurements.

Peer Reviewed