Viscosities and working region predictions for bismuth aluminoborosilicate glasses

Abstract Bismuth aluminoborosilicate glasses were prepared using a standard melt‐quench technique, and the viscosity and thermal properties were measured and analyzed. Electron microprobe analysis was used to examine glass homogeneity. Fragility was calculated based on Mauro–Yue–Ellison–Gupta–Allan model fits to the viscosity curves. The system is characterized by an open structure with high fragility (44‐59). Based on microanalysis and differential scanning calorimetry results, the addition of network intermediate Al ₂ O ₃ appears to mitigate both phase separation and crystallization. From thermal property data, mixture models were created to predict the glass transition temperatures and softening temperatures as functions of composition. Based on K‐fold validation findings, the first‐order mixture model predictions of glass transition and softening appear to approximate actual values better than models with any additional second‐order terms.