EN
The differential scanning calorimetry measurements were made on a series of bismuth-iron-phosphate glasses over a temperature range around the glass transition temperature. The activation energy for structural relaxation, ΔH, was determined and found to increase with the metal-to-phosphorus ratio. The differential scanning calorimetry data were analyzed using the Adam-Gibbs-Scherer model of the glass transition. This analysis suggests that these glasses undergo a transition from the strong to the fragile glass regime as the metal-to-phosphorus ratio is increased.