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Phase Equilibria in the System CuMnO
Author(s) -
Driessens F. C. M.,
Rieck G. D.
Publication year - 1967
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.19673510108
Subject(s) - spinel , tetragonal crystal system , phase (matter) , crystallography , monoclinic crystal system , materials science , analytical chemistry (journal) , delafossite , phase diagram , chemistry , crystal structure , metallurgy , oxide , organic chemistry , chromatography
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‐Mn 2 O 3 , a phase Cu x Mn 3−x O 4+γ (0 ⩽ x < 0.2 and 0 < γ < 0.02) with a tetragonally deformed spinel structure, a cubic spinel phase Cu x Mn 3−x O 4+γ (0 ⩽ x ⩽ 1.03 and −0.08 < γ < 0.02), a crednerite‐like phase Cu y Mn 1−y O (0.50 < y < 0.53) with monoclinic structure, a delafossite‐like phase Cu y Mn 1−y O (0.54 < y < 0.60) with hexagonal structure, a liquid phase, the phase Cu 2 O and the phase CuO. CuMn 2 O 4 was found to be cubic or tetragonal at room temperature, depending on the temperature of quenching. The po 2 ‐x‐section of the system CuMnO at 1,000°C, as determined by S CHMAHL and M ÜLLER (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.