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

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

Research output: Contribution to journalArticle

28 Citations (Scopus)

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 1 2012

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Ferrosoferric Oxide
solid solution
magnetite
Solid solutions
calorimetry
Calorimetry
solid solutions
thermodynamics
enthalpy
Thermodynamics
Enthalpy
heat measurement
Oxides
Cations
cation
oxide
cations
ilmenite
oxides
molybdates

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Geochemistry and Petrology

Cite this

Lilova, Kristina I. ; Pearce, Carolyn I. ; Gorski, Christopher Aaron ; Rosso, Kevin M. ; Navrotsky, Alexandra. / Thermodynamics of the magnetite-ulvöspinel (Fe 3O 4-Fe 2TiO 4) solid solution. In: American Mineralogist. 2012 ; Vol. 97, No. 8-9. pp. 1330-1338.
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Thermodynamics of the magnetite-ulvöspinel (Fe 3O 4-Fe 2TiO 4) solid solution. / Lilova, Kristina I.; Pearce, Carolyn I.; Gorski, Christopher Aaron; Rosso, Kevin M.; Navrotsky, Alexandra.

In: American Mineralogist, Vol. 97, No. 8-9, 01.08.2012, p. 1330-1338.

Research output: Contribution to journalArticle

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AU - Navrotsky, Alexandra

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