Ageing kinetics and internal friction of oxide glasses

The detailed analysis of internal friction data of silicate and phosphate glasses (frequencies of about I Hz) was done in comparison with the calculated temperature positions expected from the characteristic times of ageing which resulted from previous systematization of alkali-containing silicate glasses. As basis suggested for such comparison is the validity of secondary relaxation mechanism at high-temperature mechanical relaxation to that for ageing kinetics at room temperature. Practically in all cases the relaxation times for the ageing process fit the distribution of relaxation times for internal friction. Thus the beta-relaxation maximum (internal friction) may be considered as overlapping four narrow spectral components, at least. The characteristic times for ageing, contrary to continuous distribution for the mechanical relaxation, are discrete due to the condition of structure ordering. The nonbridging oxygens seem to be more probable participants of elementary relaxation events in both kinds of processes.