Mixed-valent oxides

The mixed valent oxide Mn.O occurs in nature as the mineral hasumannite. The stmcture of this ferromagnetic material has been the subject of much dispute. Mn.O is the most stable of the manganese oxides, and is formed when any of the other oxides or hydroxides are heated in air above 940—1000°C. The oxidation of aqueous solutions of Mn (OH)2 can also lead to the formation of Mn O. ... 

Figure 4 Crystal structure of the mixed valent oxide Te2Os. The [Te(VI)Og] octahedra are linked to chains via common edges, and the chains are connected by [Te(IV)04]2 dimers.

Mixed-Valent Oxides of Vanadium—VeOi3 and LiVsOs... 

Cobalt sulfide and arsenide ores are often found mixed with those of nickel and copper. The mixed ore is roasted with Na2C03 and KNO3, which removes part of the sulfur and arsenic as volatile species. The residue contains the metal oxides, as well as sulfate and arsenate, and the latter are removed by leaching with water. The metal oxide mixture is then dissolved in hot HCl or H2SO4, and the individual metal oxides are fractionally precipitated using Ca(OH)2 and NaOCl. This process gives the mixed valent oxide C03O4, which is then reduced to the metal by treatment with charcoal. 

The intramolecular electron exchanges among the different metal sites of polynuclear /3-diketonate-metal complexes are a matter of intrinsic interest, especially as far as the stabilization of mixed-valent oxidation states is concerned " . Obviously, the pertinent electrochemical pattern, while becoming richer and richer, also tends to become more... 

For diiron complexes Mossbauer spectroscopy allows to asses (1) oxidation and spin states of the iron atoms, (2) diamagnetism and ferromagnetism of the groimd state for diferric and mixed-valent oxidation levels and (3) valence (de)localisation in the solid state for mixed-valence complexes [2,3]. Isomer shifts (IS) in the range 0.35-0.60 mm/s are characteristic of 5- or 6-coordinate high-spin diferric p-hydroxo complexes [2,3], Tetrahedral high-spin ferric iron has lower isomeric shifts in the range of 0.22 mm/s [2,3]. For isolated ferric iron with S =... 

The discovery of mixed valent oxide superconductors opened up the possibility that room temperature superconducting materials may one day be obtained. Although Tc values around 10 K have been known for many years, the YBa2Cu307 and Tl2Ba2CaCu20g phases have yielded superconducting critical temperatures of 75-91 K and 102 K, respectively (above the boiling point of liquid nitrogen). Evidence even has been presented for filamentary superconductivity in... 

The intermediate/homologous series of mixed-valent oxides 422... 

The intermediate/homologous series of mixed-valent oxides As is evident from figs. 3-5, Ce, Pr and Tb form intermediate compounds of narrow composition ranges of which most, but not all, have compositions with the generic... 

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