Co 3O 4-Co 2ZnO 4 spinels: The case for a solid solution

Nicola H. Perry, Thomas O. Mason, Chengcheng Ma, Alexandra Navrotsky, Yezhou Shi, Joanna S. Bettinger, Michael F. Toney, Tula R. Paudel, Stephan Lany, Alex Zunger

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


In prior first-principles theoretical work we predicted a complete solid solution in the Co 3O 4-Co 2ZnO 4 system, with a negligibly small mixing enthalpy. In this work we tested this prediction on bulk, large-grained specimens across the Co 3O 4-Co 2ZnO 4 join, combining oxide melt solution calorimetry, differential scanning calorimetry, precise lattice parameter measurements, anomalous X-ray and neutron diffraction, and in situ electrical measurements. The calorimetric results confirm the presence of a solid solution at high temperatures, but with a large enthalpy of mixing that exceeds the predicted value. Because Co 3O 4 and Co 2ZnO 4 have essentially identical lattice parameters, this energetic destabilization must arise from factors other than the strain energy resulting from size mismatch. Changes in Co 3 spin states vs. temperature and zinc content are proposed to account for the positive excess enthalpy, and may also provide additional entropy to stabilize the solid solution at high temperature.

Original languageEnglish (US)
Pages (from-to)143-149
Number of pages7
JournalJournal of Solid State Chemistry
StatePublished - Jun 2012
Externally publishedYes


  • Calorimetry
  • Co O
  • Diffraction
  • Electrical conductivity
  • Mixing thermodynamics
  • ZnCo O

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Condensed Matter Physics
  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry


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