Influence of alumina on photoluminescence and thermoluminescence characteristics of Gd3+ doped barium borophosphate glasses

Gd3+ doped barium borophosphate glasses mixed with varying concentration of Al2O3 are synthesized. Photoluminescence, thermoluminescence and other spectroscopic studies viz., IR and EPR spectral studies, have been carried out. IR spectral studies of these glasses indicated that there is a gradual increase in the degree of depolymerization of the glass network with increase in the concentration of Al2O3 upto 3.0 mol%. The EPR spectral studies revealed the lowest concentration of Gd3+ ion clusters in the glass mixed with 3.0 mol% of Al2O3. The photoluminescence emission spectra exhibited strong ultraviolet blue emission at 311 under excitation at 273 nm due to 6P7/2→8S7/2 transition of Gd3+ ions. The intensity of this band is found to be enhanced four times when the glass mixed with 3.0 mol% of Al2O3 with respect to that of alumina free glass. The enrichment of this emission is attributed to the declustering of Gd3+ ions by Al3+ ions. Thermoluminescence (TL) characteristics of these glasses have also been investigated after irradiating them with different doses of γ-rays (in the range 0-8.0 kGy). The TL emission exhibited a dosimetric peak at about 200 °C. The TL output under this glow peak is observed to increase with increase of γ-ray dose. For any fixed γ-ray dose, the TL output is increased with increasing Al2O3 content up to 3.0 mol% and beyond this concentration quenching of TL is observed. The mechanisms responsible for TL emission and the variation in TL output with the concentration of Al2O3 are quantitatively discussed in terms of electron and hole centers developed due to interaction of γ-rays with the glass network. The dose response of these glass samples exhibited linear behavior in the dose range 0-8.0 kGy.