Influence of thermal treatment and radiation on some electrophysical parameters of langasite crystals

La/sub 3/Ga/sub 5/SiO/sub 14/ (LGSO) is a promising material for piezoengineering and acoustoelectronics. Studied in the present research is the influence of thermal treatment at T/spl ges/1227 K on the electrophysical parameters of langasite samples subjected to the action of direct electric current at E/spl ges/400 V/spl times/cm/sup -1/, T>627 K and /spl beta/-radiation at D/spl les/10/sup 6/ Rd. It is found that rhodium-doped LGSO crystals have an original rose-brown coloration. This coloration becomes more intense in the anode-adjacent parts at the increase of the treatment duration and the intensity of the applied electric field. Such samples are characterized by the presence of an absorption band at /spl lambda/=0.58 /spl mu/m in the optical trans-transmission spectra, electrical resistivity e>10/sup 10/ Ohm/spl times/cm, tangent of dielectric loss angle tgS/spl les/0.01 The electrical characteristics of Y-cut plates of LGSO are measured before and after thermal treatment. It is shown that after 15 minutes long electric field annealing at T/spl sime/688 K with E/spl sime/430 V/spl times/cm/sup -1/ the plates of LGSO have less stable electrical characteristics in comparison with those of samples annealed in air at T/spl ap/1223 K for 6 hours.