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Phase Equilibria of the Zinc Oxide–Cobalt Oxide System in Air
Article first published online: 6 DEC 2012
© 2012 The American Ceramic Society
Journal of the American Ceramic Society
Volume 96, Issue 3, pages 966–971, March 2013
How to Cite
Perry, N. H., Mason, T. O. (2013), Phase Equilibria of the Zinc Oxide–Cobalt Oxide System in Air. Journal of the American Ceramic Society, 96: 966–971. doi: 10.1111/jace.12103
- Issue published online: 17 MAR 2013
- Article first published online: 6 DEC 2012
- Manuscript Accepted: 22 OCT 2012
- Manuscript Received: 25 JUL 2012
- Center for Inverse Design
- Office of Basic Energy Sciences. Grant Number: DE-AC36-08GO28308
- National Science Foundation. Grant Number: DMR-1121262
Phase equilibria of the zinc oxide–cobalt oxide system were studied by a combination of X-ray diffraction and in situ electrical conductivity and thermopower measurements of bulk ceramic specimens up to 1000°C in air. Rietveld refinement of X-ray diffraction patterns demonstrated increasing solubility of Co in ZnO with increasing temperature, which is supported by the slight increase in wurtzite (Zn1−xCoxO) cell volume and lattice parameter a versus temperature determined for the phase boundary compositions. Similarly, the solubility of Zn in CoO increased with increasing temperature. In contrast, the spinel phase (ZnzCo3−zO4) exhibited retrograde solubility for Zn. Electrical measurements showed that the eutectoid temperature for transformation of rocksalt Co1−yZnyO into wurtzite and spinel is 894 ± 3°C, and the upper temperature limit of the stability of the spinel phase is 894°C–898°C for the compositions Co/(Zn+Co) = 0.82–1. The resulting composition-temperature phase diagram is presented and compared to the earlier (1955) diagram by Robin.