Crystal Chemistry and Phase Equilibria in the System CdO-PbO-O

The subsolidus portion of the system CdO‐PbO‐O was investigated at high temperatures and oxygen pressures in cold‐seal pressure vessels. Specially prepared cadmium hydroxide precipitate was used to achieve reaction equilibria. Two ternary oxide phases exist in the system: Cd2PbO4 is stable under all conditions investigated; CdPb2O5 dissociates (2CdPb2O5⇋ Cd2PbO4+Pb3O4+O2). The P‐T univariant curve was mapped. Compatibility triangles illustrate the phase equilibria of the system. Cell constants for Cd2PbO4 are: a0=5.671, b0=9.902, C0= 3.139, all ±0.001 Å. The space group was determined as Pbam (Pba2); Cd2PbO4 is isostructural with the Sr2PbO4 structure type. Derived average metal‐oxygen distances are: Cd–O 2.35 and Pb–O 2.08 Å. The structure of CdPb2O5 is not known.