Supported in part by the Natural Science and Engineering Research Council of Canada.
Spinel-Corundum Phase Equilibria in the Systems Mn-Cr-Al-O and Co-Cr-Al-O at 1373 K
Article first published online: 8 MAR 2005
Journal of the American Ceramic Society
Volume 69, Issue 6, pages 487–492, June 1986
How to Cite
JACOB, K.T., IYENGAR, G.N.K. and KIM, W.K. (1986), Spinel-Corundum Phase Equilibria in the Systems Mn-Cr-Al-O and Co-Cr-Al-O at 1373 K. Journal of the American Ceramic Society, 69: 487–492. doi: 10.1111/j.1151-2916.1986.tb07450.x
- Issue published online: 8 MAR 2005
- Article first published online: 8 MAR 2005
- Received September 4, 1985; revised copy received December 31, 1935; approved January 10, 1986.
The tie lines delineating ion-exchange equilibria between MCr2O4-MAl2O4 spinel solid solution, where M is either Mn or Co, and Cr2O3-Al2O3 solid solution with the corundum structure were determined at 1373 K by electron microprobe and E0AX point count analysis of the oxide phases equilibrated with metallic Co and Au-5% Mn. The component activities in the spinel solid solutions are derived from the tie lines and the thernodynamic data for Cr2O3-Al2O3 soiid solutions available hi the literature. The Gibbs free energies of mixing calculated from the experimental data are discussed in relation to the values derived from the cation distribution a.odel based on the site preference energies and assuming random mixing on both tetrahedral and octahedral sites. Positive deviations from ideality observed in this study suggest a miscibility gap for both series of spinel solid solutions at low temperatures in the absence of oxidation.