LUMINESCENCE STUDY OF THERMAL TREATED AND LASER-IRRADIATED BI12GEO20 AND BI12SIO20 CRYSTALS

Changes on the defect structure of Bi12GeO20 (BGO) and Bi12SiO20 (BSO) crystals induced by thermal treatments and laser irradiation have bee n studied by means of cathodoluminescence in the scanning electron mic roscope. The results have been compared to those previously reported f or untreated and electron irradiated samples and recombination mechani sms responsible for some of the observed luminescence bands are discus sed. Annealing of EGO samples causes the appearance of a new luminesce nce band at about 390 nm. The centers responsible for this band decora te the deformation slip bands in quenched EGO as observed in the catho doluminescence images. The emission observed in BSO in the same spectr al range is quenched during the annealing treatment. The annealing ind uced reduction of Bi ions to metallic Bi appears to be related to the quenching of a band at 640 nm observed in untreated samples. (C) 1998 American Institute of Physics.