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Thermodynamic Assessment of the System MnO‐NiO
Author(s) -
BERGMAN BILL,
ÅGREN JOHN
Publication year - 1985
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1985.tb10172.x
Subject(s) - thermodynamics , gibbs free energy , phase diagram , non blocking i/o , thermodynamic databases for pure substances , spinodal decomposition , solid solution , calphad , materials science , entropy (arrow of time) , thermodynamic process , phase (matter) , chemistry , physics , material properties , metallurgy , biochemistry , organic chemistry , catalysis
The thermodynamic properties of pure MnO and NiO were analyzed in terms of the Debye model and a model for the magnetic transitions. The classical formula R In (β+ 1) for the magnetic entropy was found to overestimate the effect of magnetic ordering in these systems. A previous interpretation of the data for NiO was corrected. Thermodynamic functions were derived for the solid and liquid states and are given as analytic expressions. A previous assessment of the Gibbs energy of the solid solution (Mn, Ni)O from activity data was modified on statistical grounds. The results indicate that there should be a miscibility gap below 41O°C. By estimating the Gibbs energy of the liquid phase, it was possible to calculate the complete phase diagram.