Oxidation state of copper ions in silicate glasses prepared by different methods

Abstract

Copper-aluminosilicate glasses are prepared by melting and by Cu ⇆ R ion exchange of alkali aluminosilicate glasses in molten CuCl at 550°C in air and nitrogen atmospheres. Univalent ions, Cu +, are found to be predominant in the glass prepared by melting at 1550°C. After ion exchange in nitrogen atmosphere, copper ions are uniquely present as Cu +. In the ion exchange in air, the fraction of Cu 2+ ions of the resultant glass is much larger than that of Cu + ions, although to some extent it depends on the basicity of the starting glass. The glass containing mainly Cu 2+ ions is also prepared by heating the as-melted Cu 2O·Al 2O 3·4SiO 2 glass in air at 500°C. Thermal expansion of the Cu 2+ ion-containing aluminosilicate glasses thus prepared is compared with glasses in which copper ions are present mainly as Cu +.