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High temperature stability of oxysulfides containing Ce3+ and Y3+ ions

Akila, R and Jacob, KT (1988) High temperature stability of oxysulfides containing Ce3+ and Y3+ ions. In: Ceramics International, 14 (3). pp. 147-152.

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Abstract

Standard Gibbs energies of formation of oxysulfides of cerium and yttrium from their respective oxedes were determined using solid oxide galvanic cells incorporating calcia-stabilized zirconia as the electrolyte in the temperature range 870–1120 K. The sulfur potential over the electrode containing the oxide and oxysulfide was fixed by a buffer mixture of Ag + Ag2S. A small amount of CaH2 was added to the buffer to generate an equilibrium ratio of H2S and H2 species in a closed system containing the buffer and the electrode. The sulfur potential is transmitted to the electrode via the gas phase. The results can be summarized by the equations 2left angle bracketCeO2right-pointing angle bracket+1/2(S2)→left angle bracketCe2O2Sright-pointing angle bracket+(O2) ΔG°=430600−109·7T(±400)J mol−1 left angle bracketY2O3right-pointing angle bracket+1/2(S2)→left angle bracketY2O2Sright-pointing angle bracket+1/2(O2) ΔG°=114780−1·45T(±200)J mol−1 The values are compared with data reported in the literature. The stability field diagram for the Ce---O---S system has been developed using the results of this study for Ce2O2S and data for other phases from the literature.

Item Type: Journal Article
Additional Information: Copyright of this article belongs to Elsevier Science.
Department/Centre: Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited: 12 Aug 2009 05:30
Last Modified: 19 Sep 2010 05:39
URI: http://eprints.iisc.ernet.in/id/eprint/21853

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