Dissertation (MSc Physics)The influence of Bi2O3 on the physical, structural and photoluminescence properties of Tm3+ doped borotellurite glasses with composition 10CaF2-xBi2O3-(59-x) B2O330TeO2:1Tm2O3 where x = 0, 5, 10, 15 and 20 wt.% have been studied. All samples were synthesized by using conventional melt quenching method.X-ray diffraction (XRD) and infrared (IR) spectra analysis were employed to investigate the structural change in the glass matrix from which the XRD confirmed the glassy nature for all samples while IR studies revealed the structural transformation betweenTeO4 and TeO3; BO3 and BO4; BiO3 and BiO6when Bi2O3 concentration was changed. Thermal analysis was carried out by using differential thermal analysis (DTA) which revealed that, all samples exhibit better thermal stability compared to fluoride and crystalline based materials. Through UV-Vis-NIR spectra, it was found that the increase in Bi2O3 concentration beyond 10 wt. % decreases the optical band gap values while Urbach energy values observed to exhibit an opposite trend which was attributed to the formation of more number of non-bridging than bridging oxygen’s in the glass matrix. Photoluminescence (PL) spectra (at 800 nm excitation wavelength) proved on the existence of Bi+ ions which plays the role of improving the Tm3+ emissions at 1200 nm and 1800 nm due to energy transfer process between Tm3+and Bi+ ions in the glass matrix. Through Judd-Ofelt analysis, it was found that, all samples exhibit high values of stimulated emission cross sections and radiative lifetimes which brand them to be considered as auspicious candidates for the NIR emission applications.