Oxygen potentials and phase equilibria in the system Ca-Co-O and thermodynamic properties of Ca3Co2O6 and Ca3Co4O9.163

Jacob, KT and Gupta, Preeti (2015) Oxygen potentials and phase equilibria in the system Ca-Co-O and thermodynamic properties of Ca3Co2O6 and Ca3Co4O9.163. In: JOURNAL OF SOLID STATE CHEMISTRY, 221 . pp. 57-65.

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Abstract

Oxygen potentials established by the equilibrium between three condensed phases, CaOss+CoOss+ Ca3Co2O6 and CoOss+Ca3Co2O6+Ca3CO3.93+O-alpha(9.36-delta), are measured as a function of temperature using solid-state electrochemical cells incorporating yttria-stabilized zirconia as the electrolyte and pure oxygen as the reference electrode. Cation non-stoichiometry and oxygen non-stoichiometry in Ca3Co3.93+alpha O9.36-delta are determined using different techniques under defined conditions. Decomposition temperatures and thermodynamic properties of Ca3Co2O6 and Ca3Co4O9.163 are calculated from the results. The standard entropy and enthalpy of formation of Ca3Co2O6 at 298.15 K are evaluated. Using thermodynamic data from this study and auxiliary information from the literature, phase diagram for the ternary system Ca-Co-O is computed. Isothermal sections at representative temperatures are displayed to demonstrate the evolution of phase relations with temperature. (C) 2014 Elsevier Inc. All rights reserved.

Item Type:	Journal Article
Publication:	JOURNAL OF SOLID STATE CHEMISTRY
Publisher:	ACADEMIC PRESS INC ELSEVIER SCIENCE
Additional Information:	Copy right for this article belongs to the ACADEMIC PRESS INC ELSEVIER SCIENCE, 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA
Keywords:	Oxygen non-stoichiometry; Cation non-stoichiometry; Misfit-layer calcium cobaltite; Entropy; Enthalpy of formation; Phase diagram
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	06 Feb 2015 14:42
Last Modified:	06 Feb 2015 14:42
URI:	http://eprints.iisc.ac.in/id/eprint/50773

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