STUDY OF OPTICAL AND ELECTROPHYSICAL CHARACTERISTICS OF CERIUM-CONTAINING GLASSES

The jumping conductivity (sigma(e)) on localized states close to the Fermi level at T < 200-degrees-C and the ionic conductivity (sigma(i)) at T > 250-degrees-C have been established in the alumina-silica alkalineless cerium-containing glasses. The charge transfer is realised by electron jumping on the scheme Ce3+ <-> Ce4+ (sigma(e)) and by the alkaline-earth cations (sigma(i)). In the Co-60 gamma-ray fields sigma(e) increases according to the law sigma(e) = AP(DELTA) where P is the dose rate and DELTA < 0.5 at P < 800 R/s and DELTA > 1 at P > 800 R/s, while sigma(i) decreases because of the decrease in the number of charge carriers owing to the electron-ion recombination, as P grows. Increase in the concentration (C) of CeO2 in the composition of the glass was found to enhance the degree of cerium oxidation and to cause the simultaneous presence of Ce3+ and Ce4+ in the structure with the predominant entry of Ce4+ at a concentration of CeO2 > 4.5 mol%. The increase of the concentration of CeO2 to 9 mol% and the substitution chain of Mg2+ --> Sr2+ --> Ba2+ in the glass composition lead to a drop in the luminescence intensities, correlated with the decrease of sigma due to the transition Ce3+ --> Ce4+ and suppressive action of Sr2+ and Ba2+. The kinetics of Ce3+ <-> Ce4+ transformation under the irradiation have been considered.