Role of Gd2O3 on tailoring structural and optical properties of Tb3+-activated borogermanate-tellurite glasses

Abstract Two series of borogermanate-tellurite glasses with compositions of (100-x)[35B2O3-10GeO2-55TeO2]-xGd2O3 and 28.875B2O3-8.25GeO2-45.375TeO2-(17.5-y)Gd2O3-yTb2O3 were prepared by melt-quenching method, respectively. The structural and optical properties of those glasses were studied by differential thermal analysis (DTA), Raman, Fourier transform infrared (FTIR), transmittance, photoluminescence, and X-ray excited luminescence spectra together with fluorescence decay curves in details. The DTA results show that Gd2O3-enriched borogermanate glass has better structural stability. With the elevated Gd2O3 content in borogermanate-tellurite glass, the depolymerization of 6- or 4-membered Ge[IV] ring into 3-membered one is progressively accelerated, together with an increasing number of isolated groups with short Te–O bonds judging from both the FTIR and Raman spectra. The optical performance of the borogermanate-tellurite glass reaches the best when the Tb2O3 content is 7.5 mol% based on both 378 nm ultraviolet light and X-rays excitation. Meanwhile, the scintillation efficiency of the optimized glass, with density of 5.05 g/cm3 and lifetime of 1.328 ms, is about 9.10% of the standard bismuth germinate (BGO) scintillator.