CHEMICAL DURABILITY OF COPPER PHOSPHATE-GLASSES

The chemical durability of copper phosphate glasses in deionised water and various pH buffered solutions has been examined for glasses having different compositions and oxidation states of copper. It is found that the 55 mol% CuO glass dissolves more readily than either the 40 or 50 mol% CuO glass. As the [Cu2+]/[Cu(total)] ratio in the glass decreases, the chemical durability improves and the glass transition temperature of the glass is lowered. The solution pH dependence of the dissolution rate in the oxidised and reduced glasses is found to differ. The dissolution of the oxidised glass is observed to follow a solution pH dependence observed previously in other phosphate glass compositions. However, the reduced glass exhibits an anomalous dependence of dissolution rate upon solution pH in acidic solution.