Gibbs free energies of formation of ZnAl2O4 and ZnCr2O4

Jacob, KT (1976) Gibbs free energies of formation of ZnAl2O4 and ZnCr2O4. In: Thermochimica Acta, 15 (1). pp. 79-87.

PDF 024._ZnAl2O4_&_ZnCr2O4._TCA._1976..pdf - Published Version Restricted to Registered users only Download (669kB) | Request a copy

Abstract

The standard free energies of formation of zinc aluminate and chromite were determined by measuring the oxygen potential over a solid CuZn alloy, containing 10 at.−% Zn, in equilibrium with ZnO, ZnAl2O4+Al2O3(χ) and ZnCr2O4+Cr2O3, in the temperature range 700–900°C. The oxygen potential was monitored by means of a solid oxide galvanic cell in which a Y2O3 ThO2 pellet was sandwiched between a CaOZrO2 crucible and tube. The temperature dependence of the free energies of formation of the interoxidic compounds can be represented by the equations, The heat of formation of the spinels calculated from the measurements by the “Second Law method” is found to be in good agreement with calorimetrically determined values. Using an empirical correlation for the entropy of formation of cubic spinel phases from oxides with rock-salt and corundum structures and the measured high temperature cation distribution in ZnAl2O4, the entropy of transformation of ZnO from wurtzite to rock-salt structure is evaluated.

Item Type:	Journal Article
Publication:	Thermochimica Acta
Publisher:	Elsevier Science
Additional Information:	Copyright of this article belongs to Elsevier Science.
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	05 Dec 2011 06:49
Last Modified:	05 Dec 2011 06:49
URI:	http://eprints.iisc.ac.in/id/eprint/42480

Actions (login required)

View Item