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 ⁶P_7/2→⁸S_7/2 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.