Light-induced changes in the spectrum of optical absorption in Bi_(12)TiO_(20):Cd crystal

摘要

We report the results of experimental investigation of changes induced by incoherent light with the wavelength of 625 nm in the spectrum of optical absorption in Bi_(12)TiO_(20):Cd crystal. Semiconductor light diodes emitting quasimonochromatic radiation in red (A. = 625 nm) ranges of the spectrum were used as light sources. It is established that the irradiation of the bismuth titanium oxide crystal by noncoherent light with λ = 625 nm leads to change of a spectrum of optical absorption. In darkness conditions the relaxation of the induced changes proceeds during more than 120 hours. We used a model of light-induced absorption that includes four trap centers having the normal distributions on the energy for their concentration. This levels are populated by electrons light-exited from donors to the conduction band. This model makes possible the adequate approximation for spectral dependences of induced absorption, which are relaxation.. The some parameters of defect centers in Bi_(12)TiO_(20):Cd crystal are determined.