A T-x-section of the phase diagram is proposed for the system CuMnO in air between 750 and 1,400°C. From X-ray and chemical analyses on quenched samples and from high-temperature X-ray diffraction studies the occurrence of the following phases is deduced: a cubic phase α-Mn2O3, a phase CuxMn3−xO4+γ (0 ⩽ x < 0.2 and 0 < γ < 0.02) with a tetragonally deformed spinel structure, a cubic spinel phase CuxMn3−xO4+γ (0 ⩽ x ⩽ 1.03 and −0.08 < γ < 0.02), a crednerite-like phase CuyMn1−yO (0.50 < y < 0.53) with monoclinic structure, a delafossite-like phase CuyMn1−yO (0.54 < y < 0.60) with hexagonal structure, a liquid phase, the phase Cu2O and the phase CuO. CuMn2O4 was found to be cubic or tetragonal at room temperature, depending on the temperature of quenching.
The po2-x-section of the system CuMnO at 1,000°C, as determined by SCHMAHL and MÜLLER (1964), was confirmed and could be farther extended to lower oxygen pressures.
The valencies of the cations, especially of those in the spinel structure, are discussed.
|Journal||Zeitschrift für Anorganische und Allgemeine Chemie|
|Publication status||Published - 1967|