Thermochemistry of Sodium Borosilicate Glasses


  • Supported by the U.S. Department of Energy (Contract No. DEAC02-80ER10765) and the National Science Foundation (Grant Nos. EAR 8022223 and 8405218).


Glasses synthesized in the system Na20-B 203−SiO2 were studied by high-temperature (974 K) solution calorimetry. The sign of the heats of mixing along four joins in the ternary reflects the presence or absence of glass-glass immiscibility. Calculations of binary phase diagrams using thermochemical data and a configurational entropy model give good agreement with experimental determinations, but complexities arise due to the simplicity of the entropy model used.