Physical properties, ligand field and Judd-Ofelt intensity parameters of bio-silicate borotellurite glass system doped with erbium oxide

Abstract

A glass series containing bio-silicate borotellurite (BSBT) doped with erbium oxide with composition of {[(TeO2)0.8 (B2O3)0.2]0.8 (SiO2)0.2}1-y (Er2O3)y, y = 0.01, 0.02, 0.03, 0.04, 0.05 mol fraction were fabricated using the melt quenching technique. In this glass composition, the bio-silicate was extracted from the rice husk. The X-ray fluorescence (XRF), X-ray diffraction (XRD), molar volume, density, optical absorption and luminescence properties and excitation of the glass sample were investigated. Result of x-ray diffraction (XRD) confirmed the amorphous nature of the glass. The X-ray fluorescence (XRF) verified the achievement of 98.6% of silicate from rice husk. The density is found to be increasing from 3.845 g/cm3 to 4.142 g/cm3 with the increase in the concentration of Er3+. The molar volume is also found to be increasing with concentration of Er3+, but later decreases at 0.04 and 0.05 mol fraction of erbium. The decrease may be due to the tightly packed atom giving rise to a denser glass. The obtained values of the Racah parameters are derived from the absorption spectra region with higher energy. The bonding parameters are found to increase with the increase in the concentration of Er3+ from 0.002789 to 0.002835 while the Racah parameters and nephelauxetic ratio decreased. The increase in crystal field strength also shows a strong field sites. The Judd-Ofelt (J-O) intensity parameters are derived from the UV–Vis spectra and the results showed Ω2 > Ω4 > Ω6 trend with the exception of Erbium at 0.04 mol fraction which showed Ω2 > Ω6 > Ω4 trend. The appearance of higher values of Ω2 and Ω6 indicate the presence of a stronger covalency and lower symmetry around Er3+ ions. MacCumber theory was used to determine the stimulated emission cross section from the calculated absorption cross section for 4I13/2 to 4I15/2 transition. The glass displayed intense green and a week red emission under 380 nm excitation. The width of the gain is found to shift towards the shorter wavelength which proves that this glass system is a good material for photonics and laser applications.