Thermally Stimulated Ionic and Electronic Processes and Radiation-Induced Defect Annealing in LiBaF3 Crystals

Abstract

The electronic, ionic and ion-diffusion controlled thermally stimulated relaxation (TSR) processes in X-ray irradiated (at 80 K or 290 K) nominally pure LiBaF3 fluoroperovskite crystals have been investigated in the 90–550 K range by means of the ionic conductivity, ionic thermally stimulated depolarization current (TSDC), as well as the thermally stimulated current (TSC), thermally stimulated luminescence (TSL) and the X-ray induced optical absorption spectra thermal bleaching techniques. The role of the thermoactivated ionic and ionic-electronic processes in the TSR (thermal bleaching, TSC and TSL) of X-ray irradiated crystals is studied above 250 K. The TSL efficiency (ratio TSL/TSC) versus T evidences that holes are released at ~130 K (migration of the self-trapped holes), at ~170 K and at ~220 K. The main TSL peaks seem to arise from the hole-diffusion controlled radiative charge transfer (electron tunneling) within close trapped electron and hole pairs.