Colour centre formation due to alkali metal vapour exposure and x-ray irradiation of spinel transparent glass ceramics

Colour centres produced in spinel transparent glass ceramics exposed to sodium vapour were analysed by electron spin resonance and optical absorption. A model is proposed for the possible mechanism involved in the formation of such colour centres. Radiation damage by x-rays was similarly studied, as was the effect of another alkali vapour, lithium, on the transparent glass ceramics, in order to show any correlation between colour centres produced by the different damage processes. Thermal bleaching was performed on the sodium exposed samples to investigate the nature of colour centre destruction. (author)