UV–Vis-NIR spectroscopy, structural and thermal properties of novel oxyhalide tellurite glasses with composition TeO2-B2O3-SrCl2-LiF-Bi2O3 for optical application

[Display omitted] •TeO2-B2O3-SrCl2-LiF-Bi2O3 glasses with different B2O3 (mol%) have been prepared.•The samples showed two varied behaviors from 0 to 30 and from 30 to 60 mol% of B2O3.•Generally, the prepared glass system showed high thermal stability.•The glass system showed suitability for optical fiber production. The prepared glass samples within the composition (85-x) TeO2-xB2O3-5Bi2O3-5SrCl2-5LiF (TBBSL) with x = 0, 10, 20, 30, 40, 50 and 60 mol% were synthesized. The X-ray diffraction patterns (XRD) showed the amorphous nature of the system. The density (ρ), molar volume (vm) and oxygen packing density (OPD) have been measured and calculated. The Fourier Transform Infrared (FTIR) of TBBSL glasses showed the presence of TeO3, TeO4, BO3, BO4, LiF, SrO and BiO6. Also, FTIR spectra identified that the substitution of B2O3 with TeO2 in glass system led to convert the TeO4 to TeO3 and the formation of bridging structure Te-O-B with increasing the B2O3 mol%, consequently the BO4 units convert to BO3 and so the number of non-bridging oxygen (NBO) increases. The optical band gaps (Eopt), the Urbach energy (ΔE) and refractive index (n) have been calculated from optical absorption spectra. Thermal characterization was determined by using Differential Scanning Calorimetry (DSC) at different heating rates 10, 15, 20, 25 °C/min. The prepared glasses showed high thermal stability. High reflective index and higher thermal stability made the synthesized glass system is a suitable candidate for the large bulk glass and optical fiber production.