Abstract: Stable and metastable phase equilibria in a binary Bi₂O₃-SiO₂ system were studied and a complete phase diagram
of the system was proposed with DTA and XRD. A peritectic reaction L + SiO₂←→Bi₄Si₃O₁₂ at the SiO₂-rich side of stable phase diagram was identified to have peritectic temperature
at about 1030℃ and peritectic point close to the end of the peritectic isotherm. Bi₄Si₃O₁₂ was observed to be a nearly congruently melting compound and liquidus of the peritectic
reaction was identified by quenching microstructure method. Crystallization behavior of Bi₂O₃
-SiO₂ system was also investigated. The
results show that metastable Bi₂SiO₅ crystallizes out at 845℃.

Key words: Bi₂O₃-SiO₂ system, phase relation, stable phase equilibrium, metastable phase equilibrium