Measurement of Gibbs energies of formation of CoF2 and MnF2 using a new composite dispersed solid electrolyte

Jacob, KT and Hajra, JP (1987) Measurement of Gibbs energies of formation of CoF2 and MnF2 using a new composite dispersed solid electrolyte. In: Bulletin of Materials Science, 9 (1). pp. 37-46.

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Abstract

Gibbs energies of formation of CoF2 and MnF2 have been measured in the temperature range from 700 to 1100 K using Al2O3-dispersed CaF2 solid electrolyte and Ni+NiF2 as the reference electrode. The dispersed solid electrolyte has higher conductivity than pure CaF2 thus permitting accurate measurements at lower temperatures. However, to prevent reaction between Al2O3 in the solid electrolyte and NiF2 (or CoF2) at the electrode, the dispersed solid electrolyte was coated with pure CaF2, thus creating a composite structure. The free energies of formation of CoF2 and MnF2 are (± 1700) J mol−1; {fx37-1} The third law analysis gives the enthalpy of formation of solid CoF2 as ΔH° (298·15 K) = −672·69 (± 0·1) kJ mol−1, which compares with a value of −671·5 (± 4) kJ mol−1 given in Janaf tables. For solid MnF2, ΔH°(298·15 K) = − 854·97 (± 0·13) kJ mol−1, which is significantly different from a value of −803·3 kJ mol−1 given in the compilation by Barinet al.

Item Type:	Journal Article
Publication:	Bulletin of Materials Science
Publisher:	Indian Academy of Sciences
Additional Information:	Copyright of this article belongs to Indian Academy of Sciences.
Keywords:	Chemical potential of fluorine;thermodynamic properties; electromotive force;enthalpy;entropy;free energy of formation
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	08 Dec 2011 06:29
Last Modified:	08 Dec 2011 06:38
URI:	http://eprints.iisc.ac.in/id/eprint/42586

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