Phase equilibria in the PbOx-CaO system at oxygen partial pressures of 1.01
x 105 and 1.01 x 103 Pa were experimentally
investigated. The temperatures of the eutectic reaction between PbO and
PbCa2O4 and of the peritectic melting of PbCa2O4 were
measured via differential thermal analysis at five oxygen partial pressures. The
phase transition in air between PbO and Pb3O4 was not affected by the
coexistence of PbCa2O4.