Thermoluminescence and photoluminescence characteristics of sol-gel prepared pure and europium doped silica glasses

Thermoluminescence (TL) and photoluminescence (PL) measurements have been performed on gamma-irradiated amorphous SiO2 and SiO2: Eu glass samples prepared by the sol-gel technique. In this type of silica the basic TL feature i.e. a prominent glow peak at 60 < T-m < 120degreesC is similar to that already studied in several such amorphous SiO2 samples. The temperature of the glow peak also shifts to higher values as a result of partial pre-heating treatments as has been reported earlier for other silica glasses. In the europium doped silica a prominent TL peak is obtained at around 170degreesC with a small shoulder at around 115degreesC. Significantly, a partial pre-heating for even up to 100degreesC simply removes the 170degreesC peak from the glow curve and a new peak of very low intensity is found above 300degreesC. An explanation for such strange results has been provided in this paper. Moreover, PL studies performed on the europium doped material show the presence of europium as both Eu2+ and Eu3+ in the material.