The object of the work is the investigation of some photo- and thermoinduced phenomena in Bi12SiO20 and Bi12GeO20 oxides single crystals of sillenite family with different degree of stoichiometry and doped by different impurities such as Al, Ga, Sn, Fe, Cu, Cr, Mn, V, Mo, Ag. The aim of the work is the solution of the problem of the deep centers responsible for some photo- and thermoinduced phenomena in sillenites. Methods of investigation: optical, photoelectrical, photoluminesence and vibrotional spectroscopy, magnetic circular di -chroism and optical detection of electron paramagnetic resonance, thermoactivative and dielectric spectroscopy in audio frequeney range, x-ray and spectroemissional analysis, Czochralski method of the crystal growth. The results obtained at the first time. There are determined the main features of photo- and thermochromic effects, thermal activation and the photocon ductivity quenching, the thermoelectret state formation. Para- metrs of electrically and optically activece nters are determined. The localization of Bi3+ и Bi5+ -ions in Si-positions; Cu2+, Cu3+, Ag2+, Ag+ Cr3+, Mn4+, V2+-ions in Bi-positions; Fe3+, Fe2+, Mo5 + , Mo6+ -ions in Si(Ge)-positions of crystaline lattice are deter- minede. It is elucidated the change of the charge states for the ions that results in photochromic effects. It is shown that in sil- lenites with Al-ions this effect is due to the appearence of paramagnetic centers [AlO]-type with the hole h, delokalized on the tetra- positions. Contribution of the space charge and quasi-dipole polarization has been identified. The processes of the two- and multicentral recombination have seen clearified. The simulation of the optical and thermal recharging of deep levels has been cavvied out. Photochromic effects the impurity conductivity and thermoinduced centers have been described on the basis of the configura- tion coordinate diagram. It has seen shown that for deep centers in sillenites the strong electron-phonon interaction should be taken in considera tion. That follows from the values of Urbach parameter g = 3-5 for fundamental absorption and Yuang- Riz factor S =7-10 The results of the work may be recommend for application in the field functional electronics: working out of the light space-time modulators, planar microwavegavds. Recording of the optical ho -logrames and electret devises. Optimized technologies are recommend for growth and dopping levels of sillenite crystals.
