# Gibbs energy of formation of $CuCrO_4$ and phase relations in the system Cu-Cr-O below 735 K

Jacob, KT and Kale, GM and Waseda, Y (1992) Gibbs energy of formation of $CuCrO_4$ and phase relations in the system Cu-Cr-O below 735 K. In: Thermochimica Acta, 208 . pp. 341-348.

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## Abstract

A solid state galvanic cell incorporating yttria-stabilized zirconia electrolyte and ruthenium(IV) oxide electrodes has been used to measure the equilibrium chemical potential of oxygen corresponding to the decomposition of $CuCrO_4$ in the range 590–760 K. For the reaction CuO(tenorite) + $CuCr_2O_4$(spinel) + $1.5O_2(g)\rightarrow 2CuCrO_4$(orth), $\Delta G^{XXX}$ = -183540 + 249.6T(\pm900) J $mol^{-1}$. The decomposition temperature of $CuCrO_4$ in pure oxygen at a pressure of $1.01 \times 10^5$ Pa is 735(\pm1) K. By combining the results obtained in this study with data on the Gibbs energy of formation of $CuCr_2O_4$ and $CuCrO_2$ reported earlier, the standard Gibbs energy of formation of $CuCrO_4$ and the phase relations in the system Cu-Cr-O at temperatures below 735 K have been deduced. Electron microscopic studies have indicated that the decomposition of $CuCrO_4$ to $CuCr_2O_4$ is topotactic.

Item Type: Journal Article Copyright for this article belongs to Elsevier Science B.V. Gibbs energy;galvanic cell;zirconia electrolyte;ruthenium Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy) 18 Dec 2007 19 Sep 2010 04:42 http://eprints.iisc.ernet.in/id/eprint/12767