Structure and some physical properties of the sodium ion conducting glasses inside the Na2O-Na2WO4-TiO2-P2O5 system

Abstract

A melt-quenched method is used to prepare homogeneous glasses inside the 20Na 2 O-(50-x)Na 2 WO 4 -xTiO 2 -30P 2 O 5 (0≤x≤25 mol%) system. The amorphous and glassy states of the glasses are evidenced by the X-Ray diffraction and differencial scanning calorimetry (DSC) analysis, respectively. The glasses were found to be colorless. Some physical parameters for the glasses such as density, molar volume and glass transition temperature ( T g ) are determined and depended strongly on the chemical composition of the glasses. The density and T g showed the decrease and the increase with TiO 2 content, respectively. Infrared spectroscopy (IR) and Raman spectroscopy are used to characterize their structural approach. These both techniques have allowed the identification of different phosphate structural units mainly pyrophosphate and metaphosphate in their structure. From the absorption edge studies, the values of the optical band gap ( E g ) and Urbach energy (DE) were evaluated. The optical band gap was found to depend on the glass composition and its value decreased as the content of the TiO 2 increases. The s dc conductivity of the glasses is determined and it followed and Arrhenius behavior as a function of temperature. These electrical data are analyzed by the modulus formalism.