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Gibbs energy of formation of nickel orthosilicate (Ni2SiO4)

Jacob, KT and Shukla, AK and Ramachandran, A and Kale, GM (1986) Gibbs energy of formation of nickel orthosilicate (Ni2SiO4). In: High Temperature Materials and Processes, 7 (2-3). pp. 141-148.

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Abstract

Two solid state galvanic cells:Pt, Ni + Ni2Si04 + Si02/(Y203)Zr02/Ni + + NiO, Pt (1) and Pt, Ni + NizSiOj + Si02/CaF2/Ni + + NiO, Pt (11) have been employed for the determination of the Gibbs' energy of formation of nickel orthosilicate(Ni2Si04) from nickel oxide and quartz. The emf of cell (I) was reversible and reproducible in the temperature range 925 to 1375K whereas emf of cell (11) drifted with time and changed polarity. From the results of cell (I), the Gibbs' energy of formation of nickel silicate is obtained as,2Ni0 (r.s.) + Si02 (quartz) + Ni2Si04 (olivine)Gibbs' energy of formation of the spinel form of Ni2Si04 is obtained by combining the data for olivine obtained in this study with high pressure data on olivine to spinel transition reported in the literature. The complex time dependence of the emf of cell (11) can be rationalised on the basis of formation of calcium silicates from calcium oxide, generally present as an impurity in the calcium fluoride electrolyte, and silica. The emf of cell (11) is shown to be the function of the activity of calcium oxide at the electrolyte/ electrode interface. The results provide strong evidence against the recent suggestion of mixed anionic conduction in calcium fluoride.

Item Type: Journal Article
Additional Information: Copyright of this article belongs to Walter de Gruyter GmbH & Co. KG.
Department/Centre: Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited: 07 Dec 2011 09:14
Last Modified: 07 Dec 2011 09:14
URI: http://eprints.iisc.ernet.in/id/eprint/42573

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