Properties and Crystallisation of M-SiAlON Glasses

Glasses with cation composition of M:Si:Al= 3.45:3:2 (where M= Er and Y) with varying nitrogen contents (0, 5, 8, 15 and 22 eq.%) have been prepared by ball milling in alcohol media. Results obtained for Er and Y-sialon glasses with varying nitrogen content revealed that there is a linear increase in fractional compactness, glass transition temperature, dilatometric softening temperature, microhardness and Young’s modulus, with increase in nitrogen in the glass structure. Property results are compared with glass structure data obtained by FTIR and Raman spectroscopy which show that there are slight changes in the ratios of structural Q units of tetrahedra with the addition of nitrogen. There is a slight increase in the Q4 units with decrease in Q3 units due to the fact that oxygen substitution by nitrogen causes greater crosslinking of the glass network.