Phase Relations in the System PbO–PbSiO3

Abstract Phase relations in the system PbO–PbSiO3 were determined at temperatures above 650 °C. Two new lead silicate phases, Pb5SiO7 and Pb11Si3O17 were found to be stable. The former melts incongruently at 733±1 °C to solid PbO plus liquid, and decomposes below 702±1 °C. The latter melts congruently at 728±1 °C. The compound Pb4SiO6, which has been accepted as stable, could not be confirmed.