Preparation and properties of nitrided phosphate glasses

Abstract

Nitrided phosphate glasses with the composition (in mol%) of 25 R2O ∙ 20 BaO ∙ 3 Al2O3 ∙ 52 P2O5 (R = lithium, sodium, potassium) have been prepared by remelting at 650 to 800 °C in a flowing dry ammonia atmosphere. The chemical durability of the glasses increases strongly with the nitrogen addition, as well as the glass transition and dilatometric softening temperatures and microhardness; whereas the thermal expansion coefficient diminishes with rising nitrogen contents. The kinetics of nitridation and the structural changes produced by nitrogen incorporation are also studied in these glasses.