Equilibrium Cation Distribution in NiAl2O4, CuAl2O4, and ZnAl2O4 Spinels

Journal of the American Ceramic Society - Tập 55 Số 8 - Trang 395-398 - 1972
RICHARD F. COOLEY1,2, James S. Reed2
1Now with Materials Studies Section, Owens-Illinois Technical Center, Owens-Illinois, Inc., Toledo, Ohio 43604.
2State University of New York College of Ceramics at Alfred University, Alfred, New York 14802

Tóm tắt

Stoichiometric NiAl2O4, CuAl2O4, and ZnAl2O4 spinels were prepared and equilibrated at temperatures from 600° to 1400°C. The parameters u and x, denoting the oxygen position and fraction of divalent cations on tetrahedral sites, respectively, were determined from a detailed X‐ray diffraction analysis. In NiAl2O4, x increased from 0.07 at 595° to 0.26 at 1391°C; in CuAl2O4, x decreased from 0.68 at 613° to 0.64 at 1195°C; and in ZnAl2O4, x decreased from 0.96 at 905° to 0.94 at 1197°C. The form of the temperature dependence of x could not be described using theoretically based equations advanced in the literature. A more general equation which allows for a non‐distributional contribution to the configurational entropy was derived and observed to properly describe the temperature dependence; the results indicate that short‐range order is of definite significance in these intermediate aluminate spinels.

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Journal of the American Ceramic Society

Tập 55 Số 8

395-398

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