Electrochemical determination of activities in Cr2O3 Al2O3 solid solutions

Jacob, K. T. (1978) Electrochemical determination of activities in Cr2O3 Al2O3 solid solutions Journal of the Electrochemical Society, 125 . pp. 175-179. ISSN 0013-4651

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Official URL: http://jes.ecsdl.org/content/125/2/175.abstract


The activity of Cr2O3 in Cr2O3Al2O3 solid solution has been determined in the temperature range 800°–1320°C from electromotive force measurements on the solid oxide galvanic cell Pt,Cr+CrO3/Y2O3ThO2/Cr+Cr2Al2O3,Pt The activities of Formula and Formula in the solid solution show both positive and negative deviations from Raoult's law. The heat and entropy of mixing of the solid solution obtained from the temperature dependence of the emf can be expressed as ΔH=XCr2O3XAl2O3[31.700XCr2O3+37.470XAl2O3]Jmole-1 ΔS=-1.8R[XAl2O3InXAl2O3+Al2O3InAl2O3] The entropy of mixing is 10% lower than that predicted by the Temkin model. The large positive heat of mixing in the Cr2O3Al2O3 solid solution, however, suggests that this apparent entropy discrepancy originates with the clustering of positive ions on the cation sublattice. The asymmetric miscibility gap exhibited in the Cr2O3Al2O3 system below 900°C is consistent with the thermodynamic data trends recorded at the more elevated temperatures.

Item Type:Article
Source:Copyright of this article belongs to The Electrochemical Society.
Keywords:Electrochemical Analysis; Chromium Compounds; Aluminium Compounds; Fuel Cells; Solid Electrolytes; Alumina‐Chromium Sesquioxide Solid Solution; Thermodynamics; Solid Electrolyte; Galvanic Cell; Entropy of Mixing; Enthalpy of Mixing; Activities; Miscibility Gap
ID Code:94775
Deposited On:17 Oct 2012 11:29
Last Modified:17 Oct 2012 11:29

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