Formation of copper-manganese oxides from Cu{sub x}Mn{sub 1-x}(HCOO){sub 2}{center_dot}2H{sub 2}O mixed crystals
Journal Article
·
· Journal of Solid State Chemistry
- Institute of General and Inorganic, Sofia (Bulgaria)
It has been established that two series of mixed crystals are formed in the Cu(HCOO){sub 2}-Mn(HCOO){sub 2}-2H{sub 2}O system at 25{degrees}C. The thermal decompositions of Cu{sub x}Mn{sub 1-x}(HCOO){sub 2}{center_dot}2H{sub 2}O mixed crystals (0 {le} x {le} 0.5) have been studied. On the basis of the methods used (TG, DTA, and X-ray diffraction analysis), it has been established that homogeneous and heterogeneous oxide phases are obtained depending on the x-values. At about 300{degrees}C the formates decompose to Mn{sub 5}O{sub 8} (x = 0); Cu{sub 0.4}Mn{sub 4.6}O{sub 8} (x = 0.08); a mixture of Cu{sub 1.5}Mn{sub 1.5}O{sub 4} with a different ratio (0.08 < x < 0.5), and a Cu{sub 1.5}Mn{sub 1.5}O{sub 4} spinel (x = 0.5). Cu{sub 0.4}Mn{sub 4.6}O{sub 8} (Cu{sub 0.4}{sup 2+}Mn{sub 0.4}{sup 2+}Mn{sub 3}{sup 4+}O{sub 8}) crystallizes in the monoclinic system with lattice parameters a = 10.39(1) {angstrom}, b = 5.729(4) {angstrom}, {beta} = 109.4{degrees} and space group C2/m. At about 600{degrees}C the oxides obtained transform into {alpha}-Mn{sub 2}O{sub 3} (x = 0) and a mixture of {alpha}-Mn{sub 2}O{sub 3} and Cu{sub 1.5}Mn{sub 1.5}O{sub 4} with a different ratio (0 < x < 0.5). The slowly cooled specimen shows a fine structure in the IR spectrum due to the 1:3 ordering of the ions on the B-sublattice, and the cation valences are Cu{sup +} [Cu{sub 0.5}{sup 2+}Mn{sub 4.5}{sup 4+}]O{sub 4}. The magnetic measurements show that the oxides obtained are paramagnetic in the temperature range of 25-300{degrees}C, and the 1/{chi} versus T curves obey the Curie-Weiss law. The theoretical and experimental magnetic moments of the oxides are given. They coincide well in the case of the homogeneous samples.
- OSTI ID:
- 613705
- Journal Information:
- Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 2 Vol. 133; ISSN 0022-4596; ISSN JSSCBI
- Country of Publication:
- United States
- Language:
- English
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