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

La₃Ga₅SiO₁₄ (LGSO) is a promising material for piezoengineering and acoustoelectronics. Studied in the present research is the influence of thermal treatment at T⩾1227 K on the electrophysical parameters of langasite samples subjected to the action of direct electric current at E⩾400 V×cm^-1, T>627 K and β-radiation at D⩽10⁶ 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 λ=0.58 μm in the optical trans-transmission spectra, electrical resistivity e>10¹⁰ Ohm×cm, tangent of dielectric loss angle tgS⩽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≃688 K with E≃430 V×cm^-1 the plates of LGSO have less stable electrical characteristics in comparison with those of samples annealed in air at T≈1223 K for 6 hours