The study of spectrum dependence of the absorption coefficient in sillenite crystals subjected to annealing
In the research there are presented the results of experimental investigations and approximation of the spectral dependence of optical absorption in the spectral range of 400 – 1100 nm in bismuth silicon oxide crystals annealed in vacuum at temperatures from 620 to 785°С and in air atmosphere in several stages at different temperatures from the range of 160 – 390 °С, as well as IR-radiation. Differences in the spectral dependence of the optical absorption and in sensitivity to the vacuum annealing and IR radiation for undoped Bi <sub>12</sub>SiO <sub>20</sub> crystals with different origin are shown. These differences can be the reason of the different stoichiometry of the crystals in the initial state. The approximation of the spectral dependences are carried out.