The CrCr2O3 oxygen buffer and the free energy of formation of Cr2O3 from high-temperature electrochemical measurements

A. Holzheid, H. St C. O'Neill

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The free energy of formation of Cr2O3, defined by the reaction 2 Cr + 3 2 O2 = Cr2O3 has been measured electrochemically using a yttria-doped thoria (YDT) solid electrolyte, in the temperature range from 900 to 1400 K. Fe + "FeO" was used as the reference electrode. The results have been combined with high temperature heat capacity data from the literature, to give, in J · mol -1 μO2(±170) = -758.585 + 349.718T -25.5216T + 0.00935T2 (600 K < T < 1800 K). Our results are not in good agreement with the calorimetric data and imply that the currently accepted calorimetric value for the entropy of Cr2O3 at 298.15 K may be too low by 4.6 J/K · mol.

Original languageEnglish
Pages (from-to)475-479
Number of pages5
JournalGeochimica et Cosmochimica Acta
Issue number3
Publication statusPublished - Feb 1995
Externally publishedYes

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