Abstract
This article reports on the structure of the glassy system xCuO-65TeO2-(35-x) V2O5, 5 <= x <= 10mol% which was studied using infrared (IR) and Raman spectroscopy methods as well as magnetic susceptibility measurements. IR and Raman spectroscopy analysis reveals the presence of four main absorption bands attributed to[TeO3],[TeO4],[VO4], and [VO5] structure units. It suggests that Cu2+ ions occupy the available open spaces of the Te-O network without straining the bonds too much. Increasing the concentration of Cu2+ ions beyond 5 mol% results in the modification of the glass by straining and locally distorting the surrounding of the Te-O network. The magnetic susceptibility of these materials was investigated in the temperature range of 5-200 K revealing the paramagnetic behavior described by the Curie-Weiss law and indicating the presence of weak antiferromagnetic exchange interactions between Cu ions. The magnetic entropy change of the glasses was determined based on the temperature and magnetic field dependence of magnetization. (C) 2009 Elsevier B.V. All rights reserved.