UV–Vis-NIR spectroscopy, structural and thermal properties of novel oxyhalide tellurite glasses with composition TeO 2 -B 2 O 3 -SrCl 2 -LiF-Bi 2 O 3 for optical application

Abstract

The prepared glass samples within the composition (85-x) TeO 2 -xB 2 O 3 -5Bi 2 O 3 -5SrCl 2 -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 (v m ) and oxygen packing density (OPD) have been measured and calculated. The Fourier Transform Infrared (FTIR) of TBBSL glasses showed the presence of TeO 3 , TeO 4 , BO 3 , BO 4 , LiF, SrO and BiO 6 . Also, FTIR spectra identified that the substitution of B 2 O 3 with TeO 2 in glass system led to convert the TeO 4 to TeO 3 and the formation of bridging structure Te-O-B with increasing the B 2 O 3 mol%, consequently the BO 4 units convert to BO 3 and so the number of non-bridging oxygen (NBO) increases. The optical band gaps (E opt ), 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.