Charge carrier rearrangement in spinel crystals irradiated at low temperatures

The results of an investigation of thermolurninescence (TL) in nominally pu re MgAl2O4 spinel single crystals in the temperature range between 80-670 K are presented. For a heating rate of 0.21 Ws, TL spectra exhibit glow peak s in three distinct temperature ranges: 100 160, 270 370 and 470 670 K. The most prominent peaks are at 115, 140, 305, 335, 525, 570 and 605 K. The lo cations of the temperature maxima, as well as the intensity of the peaks, v ary depending on the treatment of the crystals, the type of irradiation and the temperature of irradiation. Measurements of the glow peaks at differen t emission wavelengths and the use of partial bleaching and isothermal deca y techniques for TL, allowed us to propose mechanisms for charge carrier re arrangement at lattice defects and impurity ions, during irradiation and su bsequent heating. (C) 2000 Elsevier Science B.V. All rights reserved.