Thermodynamics of the magnetite-ulvöspinel (Fe 3O 4-Fe 2TiO 4) solid solution

Kristina I. Lilova, Carolyn I. Pearce, Christopher Gorski, Kevin M. Rosso, Alexandra Navrotsky

Research output: Contribution to journalArticlepeer-review

33 Scopus citations

Abstract

The thermodynamics of mixing and its dependence on cation distribution in the Fe 3O 4-Fe 2TiO 4 (magnetite-ulvöspinel) spinel solid solution were studied using high-temperature oxide melt solution calorimetry and a range of structural and spectroscopic probes. The enthalpies of formation of ilmenite and ulvöspinel from the oxides and from the elements were obtained using oxidative drop solution calorimetry at 973 K in molten sodium molybdate. The enthalpy of mixing, determined from the fit to the measured enthalpies of drop solution calorimetry, is endothermic and represented by a quadratic formalism, δH mix = (22.60 ± 8.46)x(1 - x) kJ/mol, where x is the mole fraction of ulvöspinel. The entropies of mixing are more complex than those for a regular solution and have been calculated based on average measured and theoretical cation distributions. Calculated free energies of mixing show evidence for a solvus at low temperature in good agreement with that observed experimentally.

Original languageEnglish (US)
Pages (from-to)1330-1338
Number of pages9
JournalAmerican Mineralogist
Volume97
Issue number8-9
DOIs
StatePublished - Aug 2012
Externally publishedYes

Keywords

  • Calorimetry
  • Enthalpies of mixing
  • Magnetite-ulvö spinel solid solution
  • Titanomagnetite

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology

Fingerprint Dive into the research topics of 'Thermodynamics of the magnetite-ulvöspinel (Fe <sub>3</sub>O <sub>4</sub>-Fe <sub>2</sub>TiO <sub>4</sub>) solid solution'. Together they form a unique fingerprint.

Cite this