Phase equilibria of the zinc oxide-cobalt oxide system in air

Nicola Helen Perry, Thomas O. Mason

Research output: Contribution to journalArticle

Abstract

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-zO 4) exhibited retrograde solubility for Zn. Electrical measurements showed that the eutectoid temperature for transformation of rocksalt Co 1-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.

Original languageEnglish (US)
Pages (from-to)966-971
Number of pages6
JournalJournal of the American Ceramic Society
Volume96
Issue number3
DOIs
StatePublished - Mar 1 2013
Externally publishedYes

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ASJC Scopus subject areas

  • Ceramics and Composites
  • Materials Chemistry

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