Kinetics of relaxation and crystallization of sodium metaphosphate glass

Abstract Kinetics of structural relaxation and crystallization of NaPO 3 glassforming melt is studied by means of thermal analyses. It is demonstrated that activation energy depends strongly on fictive temperature T f . The dependence of the onset temperature T o of the glass transition interval on the heating rate q + is investigated for samples that were previously cooled down at a rate q − of about 850 K/min. The dimensionless fragility F is a measure of the dependence of the activation energy for spatial rearrangement on the changes of structure. According to the present results F is large for NaPO 3 (i.e. phosphates are ‘fragile’ substances).