Phase equilibria in the system Sm-Rh-O and thermodynamic and thermal studies on SmRhO3

Jacob, KT and Gupta, Preeti and Han, Donglin and Uda, Tetsuya (2014) Phase equilibria in the system Sm-Rh-O and thermodynamic and thermal studies on SmRhO3. In: JOURNAL OF MATERIALS SCIENCE, 49 (8). pp. 3135-3145.

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Abstract

Using isothermal equilibration, phase relations are established in the system Sm-Rh-O at 1273 K. SmRhO3 with GdFeO3-type perovskite structure is found to be the only ternary phase. Solid-state electrochemical cells, containing calcia-stabilized zirconia as an electrolyte, are used to measure the thermodynamic properties of SmRhO3 formed from their binary component oxides Rh2O3 (ortho) and Sm2O3 (C-type and B-type) in two different temperature ranges. Results suggest that C-type Sm2O3 with cubic structure transforms to B-type Sm2O3 with monoclinic structure at 1110 K. The standard Gibbs energy of transformation is . Standard Gibbs energy of formation of SmRhO3 from binary component oxides Rh2O3 and Sm2O3 with B-type rare earth oxide structure can be expressed as . The decomposition temperature of SmRhO3 estimated from the extrapolation of electrochemical data is 1665 (+/- 2) K in air and 1773 (+/- 3) K in pure oxygen. Temperature-composition diagrams at constant oxygen pressures are constructed for the system Sm-Rh-O. Employing the thermodynamic data for SmRhO3 from emf measurement and auxiliary data for other phases from the literature, oxygen potential-composition phase diagram and 3-D chemical potential diagram for the system Sm-Rh-O at 1273 K are developed.

Item Type:	Journal Article
Publication:	JOURNAL OF MATERIALS SCIENCE
Publisher:	SPRINGER
Additional Information:	copyright for this article belongs to SPRINGER, 233 SPRING ST, NEW YORK, NY 10013 USA
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	25 Mar 2014 09:42
Last Modified:	25 Mar 2014 09:43
URI:	http://eprints.iisc.ac.in/id/eprint/48707

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