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Equilibrium Order-Disorder in Spinels
Article first published online: 2 JUN 2006
Journal of the American Ceramic Society
Volume 50, Issue 11, pages 578–583, November 1967
How to Cite
DATTA, R. K. and ROY, R. (1967), Equilibrium Order-Disorder in Spinels. Journal of the American Ceramic Society, 50: 578–583. doi: 10.1111/j.1151-2916.1967.tb15002.x
Presented at the Sixty-Fourth Annual Meeting, The American Ceramic Society, New York, N. Y., May 2, 1962 (Electronics Division, No. 12-L-62).
This work formed part of the research in Crystal Chemistry supported by the Institute of Exploratory Research of the United States Signal Corps Engineering Laboratories under Contract DA36–039 SC-85311 and appeared as Technical Report No. 3 with the Final Report dated October 20, 1961.
At the time this work was done the writers were, respectively, research associate, Department of Geophysics and Geochemistry, and director, Materials Research Laboratory, The Pennsylvania State University.
- Issue published online: 2 JUN 2006
- Article first published online: 2 JUN 2006
- Received November 15, 1966; revised copy received April 28, 1967.
The distribution of cations in different coordinations in the spinel structure as a function of equilibrium temperature was quantitatively determined for several phases. The spinels were synthesized and/or reacted at various temperatures and pressures. The relative X-ray intensities of various reflections of the quenched phases were measured and compared with intensities calculated for various models of cation distribution. In NiAl2O4 the cation arrangements at 600° and 1550°C are (Al1.0)IV(Ni1.0 Al1.0)VIO4 and (Ni0.25Al0.75)IV(Ni0.75Al1.25)VIO4, respectively. In Ni2GeO4, between 610° and 1400°C, the concentration of Ni2+ ions in tetrahedral sites increases from 0 to 23% and in octahedral sites it decreases from 100 to 77% of total nickel present. All these transitions were reversible under equilibrium conditions and can be classified as second-order “reconstructive transition of disorder.” Many spinels cannot be classified as normal or inverse but have a cation distribution which is an equilibrium function of the temperature.