XANES Studies on the Oxidation States of Copper Ion in Silicate Glass

Abstract

The silicate glass was prepared using rice husk as the source of silica. The base glass formula is composed of SiO2 (from rice husk ash), Na2CO3, K2CO3, ZnO, H3BO3, CaO and Al2O3 or Al. CuO was used as the colorant in the glass matrix in the absence and presence of reducing agent. The color of the glass obtained was varied from dark blue to blue depending on the amount of CuO and reducing agent. The expansion coefficients of copper doped glass are in the range of 12.43 x 10-6 - 14.35 x 10-6 (°C-1) which is common for the silicate glass. The finger prints of the bond vibrations were studied using IR spectroscopy. While the oxidation state and the coordination information of the copper ion in the glass matrix were investigated using X-ray absorption spectroscopy. In the absence and presence of reducing agent, Cu+ and Cu2+ exist in the glass matrix. However, in the presence of reducing agent, the amount of Cu+ in the glass matrix is higher.