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Studies in the system Mn-O--The Mn 2 O 3 -Mn 3 O 4 and Mn 3 O 4 -MnO equilibria
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1960
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Chemical KineticsDynamic EquilibriumEngineeringPhase EquilibriaChemistryThermodynamicsEquilibrium Thermodynamic Property-Mno EquilibriaInorganic ChemistryPhysicsSystem Mn-oSolidus Temperature RegionO 4CrystallographyNon-equilibrium ProcessEquilibria 6MnPhase EquilibriumNatural SciencesCondensed Matter PhysicsEquilibrium ThermodynamicsMn 3
As a first step in an investigation of phase relations in the system Mn-O, the equilibria 6Mn <sub>2</sub> O <sub>3</sub> = 4Mn <sub>3</sub> O <sub>4</sub> + O <sub>2</sub> and 2Mn <sub>3</sub> O <sub>4</sub> = 6MnO + O <sub>2</sub> have been studied in the temperature intervals 845 to 1029 degrees C. and 1248 to 1562 degrees C., respectively, and at O <sub>2</sub> partial pressures ranging from 0.21 to 1 atm. and from 10 (super -3.66) to 0.21 atm. respectively. The conditions for coexistence of 2 crystalline phases in stable univariant equilibria are expressed as follows: Mn <sub>2</sub> O <sub>3</sub> , Mn <sub>3</sub> O <sub>4</sub> : log p (sub O <sub>2</sub> = 8.05 - 10100 . 1/T; Mn <sub>3</sub> O <sub>4</sub> , MnO : log p (sub O <sub>2</sub> = 13.31 - 26000 . 1/T. Exploratory runs in the solidus temperature region for the composition range between MnO and Mn <sub>3</sub> O <sub>4</sub> indicate the presence of a eutectic at approximately 1540 degrees C. An explanation is offered for the poor agreement among previously published data on these equilibria.