Effect of Fe on the structure of potassium borosilicate glasses

Abstract

The behavior of Fe in the structure of Fe-containing potassium borosilicate glasses with different relationships between network-forming and modifier cations has been studied by Mössbauer and vibrational spectroscopies. The results demonstrate that the Fe-free and Fe-containing potassium borosilicate glasses differ in the distribution of the modifier cations over their structural units. The presence of Fe in the composition of potassium borosilicate glasses is shown to reduce the coordination of the boron, which shows up as a decrease in the percentage of BO 4 tetrahedra and an increase in that of BO 3 triangles. This is accompanied by an increase in the percentage of Q 3 silicon-oxygen structural units containing nonbridging oxygens, the breaking of mixed silicon borate rings, and the formation of Si-O-Fe 3+ bridge bonds and Si-O − nonbridging bonds coordinated by K + ions.