Ceramics and Composite Materials

Biography

Biography: Nehal Elkhoshkhany

Abstract

Quaternary tellurite glass systems in the form ((75-x) TeO2 - 20ZnO-5Na2Co3 - xEr2O3) glass samples with 0≤ x≤ 2.5 mol %) have been prepared by the melt quenching technique. Density, molar volume and oxygen packing density of every glass composition have been measured and calculated. Differential Scanning Calorimetry (DSC) have been carried out on the prepared glass systems in the temperature range 300-800 ºC at heating rate 10, 15, 20 oC/min. The glass transition Tg and crystallization Tc temperatures values were measured from DSC. Kinetics parameters like activation energy of relaxation structure Et , activation energy of crystallization Ec and order of crystallization have been calculated for every glass composition. Number of bonds per unit volume (nb) and average stretching force constant (have been calculated to interpret the experimental data). Transparent glass ceramics were prepared by controlled one step heat treatment method. The crystal structure was investigated by using X-ray Diffraction (XRD) and Scanning electron microscopy (SEM). The XRD results and SEM micrograph reveal the presence of two crystalline phases: α TeO2 and Zn2Te3O8 phases during the crystallization process of the prepared glass. Optical absorption studies are carried out on the glassy system in the wavelength range of 300– 900 nm. The cut-off wavelength λc, optical band gap Eopt, Urbach energy ΔE and refractive index n values were calculated. Also, different physical parameters such as, molar refraction RM, metallization criterion M, electronic polarizability of the oxide ion αo2- (calculated from Eopt) and optical basicity Λ have been determined.