Experimental studies and thermodynamic assessment of the Ba-Mo-O system by the CALPHAD method. Issue 6 (June 2021)

• Record Type: Journal Article
• Authors: Smith, A.L.; Rutten, M.; Herrmann, L.; Epifano, E.; Konings, R.J.M.; Colineau, E.; Griveau, J.-C.; Guéneau, C.; Dupin, N.
• Is Part Of: Journal of the European Ceramic Society. Volume 41:Issue 6(2021)
• Page Start: 3664
• Page End: 3686
• Publication Date: 2021-06
• Subjects: Barium-molybdenum-oxygen system -- Differential Scanning Calorimetry -- Thermal-relaxation calorimetry -- XANES -- CALPHAD; Ceramic materials -- Periodicals; Composite materials -- Periodicals; Matériaux céramiques -- Périodiques; Composites -- Périodiques; Ceramic materials; Composite materials; Periodicals; Electronic journals; 666.05
• DOI: 10.1016/j.jeurceramsoc.2021.01.010
• Languages: English
• ISSNs: 0955-2219

Abstract

Abstract: Thermodynamic measurements on BaMoO4, BaMoO3 and BaMo3 O10 are reported, that served as input for the development of a thermodynamic model of the Ba-Mo-O system using the CALPHAD methodology. The valence states of molybdenum in BaMoO4 and BaMoO3 were confirmed to be VI and IV, respectively, from X-ray Absorption Near Edge Structure Spectroscopy measurements at the Mo K-edge. The heat capacity at low temperatures of these compounds was obtained from thermal-relaxation calorimetry. Phase equilibrium data in the BaMoO4 -MoO3 section were also measured, and the transition enthalpy associated with the peritectic decomposition of BaMo3 O10 was determined using Differential Scanning Calorimetry. The developed thermodynamic model used the compound energy formalism for intermediate compounds, and an ionic two-sublattice model for the liquid phase. The optimized Gibbs energies were assessed with respect to the known thermodynamic and phase equilibrium data. A good agreement is generally obtained, but a number of ill-defined data were also identified.