Abstract
Thermodynamic properties of ternary compounds, cuprous and cupric chromites (CuCro2, CuCr2O4), and oxygen potentials corresponding to three three-phase regions in the Cu-Cr-O system have been measured in the temperature range 900 to 1350 K using a solid state galvanic cell incorporating calcia-stabilized zirconia. Cuprous chromite was found to be nearly stoichiometric. The compositions of non-stoichiometric cupric chromite saturated with CuO and Cr2O3 have been determined using electron microprobe and energy dispersive X-ray analysis. The results of this study resolve discrepancies in Gibbs' energies of cuprous and cupric chromites reported in the literature. A ternary phase diagram for the Cu-Cr-O system at 1150 K and phase relations in air for the Cu2O-CuO-Cr2O3 system as a function of temperature have been derived based on the new thermodynamic data. The phase diagram given in the literature is found to be inaccurate.
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Jacob, K.T., Kale, G.M. & Iyengar, G.N.K. Oxygen potentials, Gibbs' energies and phase relations in the Cu-Cr-O system. J Mater Sci 21, 2753–2758 (1986). https://doi.org/10.1007/BF00551483
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DOI: https://doi.org/10.1007/BF00551483