Synthesis of 30Na2O-70P2O5. (NH4)2HPO4 and Na2CO3 were weighed and mixed in the appropriate proportions. The 50 g batches were then melted at 900°C for one hour in alumina crucibles and quenched to form homogeneous glassy samples. After quenching, the glass was annealed at 20 °C below Tg for 30 minutes and allowed to cool to room temperature.