Thermal expansion and glass transition temperature of the rare-earth doped oxynitride glasses

SiAlON glasses: Effects of nitrogen on structure and properties

“…Similar non-linearity is observed by Lofaj et al 26) and the data given by Sun et al 5) show virtually no change in CTE with increasing nitrogen content. Accordingly, it can be said that there is currently no clear correlation between CTE and nitrogen content and, therefore, in applications where this property requires careful control for matching with other materials, the modifier type and concentration would be more secure material design strategies.…”

“…Figure 6 shows a plot of molar volume and compactness data as a function of nitrogen substitution for a 37Y:42Si:21Al (eq.%) glass 33) and clearly shows a good linear correlation. Such linearity has previously been presented by Pomeroy et al 6) and analysis of the data of Lofaj et al 26) also shows that molar volume and fractional glass compactness as a function of nitrogen content of the glasses are reasonably linear. The changes in compactness indicate that the replacement of oxygen by nitrogen induces a contraction of the glass structure, which is linked to the increased coordination of nitrogen compared to oxygen.…”

“…Figure 7 also shows that there is linear correspondence between microhardness and fractional glass compactness. Analysis of the density and hardness data of Lofaj et al, 26) for La-Si-Mg-ON glasses with nitrogen contents in the range 0 to 28 eq.% also shows linear correspondence between fractional glass compactness and hardness. Recently acquired data for Ca-and Ca-Y-Si-Al-ON glasses 27) confirm linear relationships between Young's modulus and fractional glass compactness and between hardness and fractional glass compactness.…”

“…Littleton softening temperatures 26) and dilatometric softening temperatures 6),24),33) also increase linearly with nitrogen content and Table 5 gives linear regression analysis results for these data. In general, comparison of Tables 4 and 5 for the same glasses indicate that the slopes of the plots of dilatometric softening temperature v. nitrogen content are similar to those for glass transition temperature v. N, i.e.…”

“…The compositions of some well characterised glasses, that is, for which significant property data have been collected, 3)-6),17),23)- 26) are given in Table 1. Due to the fact that the compositions are based upon charge alone and that different modifiers have different valencies and different atomic weights, it is useful to give some reference to weight and atomic percentages of nitrogen.…”