Abstract:
The effect of d.c. electrolysis on the devitrification reaction of an aluminosilicate glass of composition Alv2Ov3•2SiOv2 is discussed. A D.T.A. technique has been evolved for direct observation of the effect of electrolysis on the temperature at which the reaction occurs and the heat generated on devitrification. The effect of transition metal ions on the D.T.A. parameters has also been studied, both in electrolysed and unelectrolysed samples.
The valence and site symmetry of first row transition metals in the glass have been established using absorption spectrophotometry, E.S.R. and magnetic techniques. These data have been used to interpret the observed D.T.A. Results in terms of octahedral site preference of the individual ions.
Extensive a.c. and d.c. conductivity measurements have been reported and the influence of factors such as alkali and transition metal concentration, atmosphere, and devitrification is discussed for data collected over a range of frequencies and temperatures. These data, together with the D.T.A. Results, have led to the proposal of a detailed conduction mechanism involving both protons and naturally occurring alkali impurities in the glass.
