Mannir Dahiru, Abdullahi Usman, and D. G. Diso

Keywords: Holmium oxide, Borotellurite glass, Refractive index, Optical band gab energy and Urbach energy.

Abstract

A glass network system of Holmium doped Zinc borotellurite glass with chemical formula {((TeO2)0.7 (B2O3)0.3)0.7 (ZnO)0.3}1−x (Ho2O3)x where x = 0.005, 0.01, 0.02, 0.03 and 0.04 Molar fraction was prepared by using conventional melt-quenching method. X-ray diffraction analysis (XRD) and Fourier Transform infrared analysis (FTIR) were used to determine the structural properties of the fabricated glass. XRD results confirmed that the prepared glass is amorphous. Density and molar volume of the glass were measured and calculated. The values of the density increase with increase of dopant concentration while molar volume decreases accordingly. The crystalline volume, oxygen molar volume, excess volume and oxygen packing density are also calculated to confirm the structural properties of the fabricated glass. Ultraviolet visible spectroscopy analysis (UV–Vis) was used to determine the optical properties of the prepared glass. The refractive index, molar refraction, molar electronic polarizability, metallization criterion, indirect optical energy band gap, Urbach energy, polaron radius and optical basicity were also calculated and analyzed. The refractive index was found to increase with increase of holmium ion Ho3+ concentration, optical energy band gap decreases while electronic polarizability increases in conformity with increase of refractive index as the concentration of the dopant increases.