Dissociation Pressures of Various Metallic Oxides

Abstract

Abstract Gases evolved during a vacuum heat treatment of various oxides were analyzed by means of an omegatron mass spectrometer. Carbon dioxide, carbon monoxide and water were detected as main gases evolved at lower temperatures. Oxygen due to thermal dissociation of ZnO, CdO, NiO, CuO, Cu2O, and WO3 was found at high temperatures. In the case of MoO3, however, evolution of oxygen was not observed. The equilibrium pressures of the evolved gases over these oxides have been measured with a McLeod gauge and a Knudsen gauge. The oxygen dissociation pressures of ZnO, CdO, NiO, CuO, and Cu2O were measured and compared with the calculated values.