Radiation and thermally induced effects in YAlO_3:Mn crystals

摘要

We have studied effects induced by γ-radiation and temperature in Mn-doped YAlO_3 crystals. The studies have been performed by means of optical spectroscopy that include measuring of optical absorption changes induced by γ-radiation and elevated temperature as well as thermally stimulated luminescence (TSL). It has been shown that under γ-irradiation of YAlO_3:Mn crystals, along with the ionization of Mn_(Al)~(4+) ions (Mn_(Al)~(4+)→Mn_(Al)~(5+)+e~-), some additional coloration processes take place. This additional coloration is characterized by a wide intense band centered at 26,000-25, 000 cm~(-1) that is ascribed to color centers intrinsic to YAlO_3 lattice. This coloration is removed by the way of crystal warming at T≥350 K, while the coloration caused by Mn_(Al)~(5+) ions is removed at higher temperature (T≥500 K). The observed TSL glow of irradiated crystals reveals three peaks near 360, 400 and 500 K that correspond to three types of traps. Parameters of the traps have been determined. The TSL emission corresponds to intra-center luminescence of Mn_(Al)~(4+) and Mn_Y~(2+) ions. The possible ionization and trapping mechanisms in YAlO_3:Mn crystals are discussed.