Temperature/Composition Phase Diagram of the System Bi2O3‐PbO

The Bi2O3-PbO phase diagram was determined using differential thermal analysis and both room- and high-temperature X-ray powder diffraction. The phase diagram contains a single eutectic at 73 mol% PbO and 635°C. A body-centered cubic solid solution exists above ∼600°C within a composition range of 30 to 65 mol% PbO. The compounds α-Bi2O3, σ5-Bi2O3, and γ-PbO (litharge) have wide solubility ranges. Four compounds, 6Bi2O3·PbO, 3Bi2O3·2PbO, 4Bi2O3,5PbO, and Bi2O3·3PbO, are formed in this system and the previously unreported X-ray diffraction patterns of the latter three compounds are reported. Diffraction patterns for some of these mixed oxides have been observed in ZnO-based varistors grown using Bi2O3 and PbO as sintering aids.