Abstract
Fe3O4 has been studied by high-pressure diffraction to 43 GPa. No major changes in the spinel-type structure of magnetite is observed below 21.8 GPa. At higher pressure a sluggish transition to a highpressure modification, h-Fe3O4, is observed. The X-ray diffraction pattern of the high-pressure modification is consistent with the orthorhombic unit cell (CaMn2O4-type structure, space group Pbcm) recently proposed for h-Fe3O4 by Fei et al. (1999), however, it is also consistent with a more symmetric CaTi2O4- type structure (space group Bbmm). Bulk modulus values for magnetite, KT0 = 217 (2) GPa, and h-Fe3O4, KT0 = 202 (7) GPa, are calculated from the pressure-volume data using a third-order Birch-Murnaghan equation of state. A thermodynamic analysis of the Fe-O system at high pressure is presented. The proposed equation of state of h-Fe3O4 gives an increased stability of wüstite relatively to a two-phase mixture of iron and h-Fe3O4 compared to earlier equations of state and removes an inconsistency in the thermodynamic description of the Fe-O system at high pressure.
© 2015 by Walter de Gruyter Berlin/Boston
Articles in the same Issue
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- A crystal chemical re-evaluation of amphibole/melt and amphibole/clinopyroxene DTi values in petrogenetic studies
- Mineralogy of mafic xenoliths and their reaction zones in the olivine lamproite from Prairie Creek Arkansas and the paragenesis of haggertyite, Ba [Fe6Ti5Mg]O19
- Magmatic anhydrite in granitic rocks: First occurrence and potential petrologic consequences
- Crystal chemistry of Al-rich biotites coexisting with muscovites in peraluminous granites
- Spectroscopic and structural properties of synthetic micas on the annite-siderophyllite binary: Synthesis, crystal structure refinement, Mössbauer, and infrared spectroscopy
- Thermodynamic properties of tremolite: A correction and some comments
- Raman spectroscopic characteristics of Mg-Fe-Ca pyroxenes
- Hydrogen in diopside: Diffusion profiles
- Diffusion of C and O in calcite at 100 MPa
- Solubility and stability of zeolites in aqueous solution: II. Calcic clinoptilolite and mordenite
- TEM and SFM of exsolution and twinning in an alkali feldspar
- Equation of state of magnetite and its high-pressure modification: Thermodynamics of the Fe-O system at high pressure
- Optimization of site occupancies in minerals using quadratic programming
- Leverage analysis and structure refinement of minerals
- The absolute energy positions of conduction and valence bands of selected semiconducting minerals
- Antiferroelectric phase transition in titanite: Excess entropy and short range order
- P4/n and P4nc long-range ordering in low-temperature vesuvianites
- Tetrahedral vacancies and cation ordering in low-temperature Mn-bearing vesuvianites: Indication of a hydrogarnet-like substitution
- Sodic-ferripedrizite, a new monoclinic amphibole bridging the magnesium-iron-manganese-lithium and the sodium-calcium groups
- The crystal structure of peprossiite-(Ce), an anhydrous REE and Al mica-like borate with square-pyramidal coordination for Al
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- Quetzalcoatlite: A new octahedral-tetrahedral structure from a 2 × 2 × 40 μm3 crystal at the Advanced Photon Source-GSE-CARS Facility
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Articles in the same Issue
- Iron concentration and the physical processes of dynamic oxidation in an alkaline earth aluminosilicate glass
- A crystal chemical re-evaluation of amphibole/melt and amphibole/clinopyroxene DTi values in petrogenetic studies
- Mineralogy of mafic xenoliths and their reaction zones in the olivine lamproite from Prairie Creek Arkansas and the paragenesis of haggertyite, Ba [Fe6Ti5Mg]O19
- Magmatic anhydrite in granitic rocks: First occurrence and potential petrologic consequences
- Crystal chemistry of Al-rich biotites coexisting with muscovites in peraluminous granites
- Spectroscopic and structural properties of synthetic micas on the annite-siderophyllite binary: Synthesis, crystal structure refinement, Mössbauer, and infrared spectroscopy
- Thermodynamic properties of tremolite: A correction and some comments
- Raman spectroscopic characteristics of Mg-Fe-Ca pyroxenes
- Hydrogen in diopside: Diffusion profiles
- Diffusion of C and O in calcite at 100 MPa
- Solubility and stability of zeolites in aqueous solution: II. Calcic clinoptilolite and mordenite
- TEM and SFM of exsolution and twinning in an alkali feldspar
- Equation of state of magnetite and its high-pressure modification: Thermodynamics of the Fe-O system at high pressure
- Optimization of site occupancies in minerals using quadratic programming
- Leverage analysis and structure refinement of minerals
- The absolute energy positions of conduction and valence bands of selected semiconducting minerals
- Antiferroelectric phase transition in titanite: Excess entropy and short range order
- P4/n and P4nc long-range ordering in low-temperature vesuvianites
- Tetrahedral vacancies and cation ordering in low-temperature Mn-bearing vesuvianites: Indication of a hydrogarnet-like substitution
- Sodic-ferripedrizite, a new monoclinic amphibole bridging the magnesium-iron-manganese-lithium and the sodium-calcium groups
- The crystal structure of peprossiite-(Ce), an anhydrous REE and Al mica-like borate with square-pyramidal coordination for Al
- Crystal chemistry of the new mineral brandholzite, Mg(H2O)6[Sb(OH)6]2, and of the synthetic analogues M2+(H2O)6[Sb(OH)6]2 (M2+ = Mg, Co)
- Letters. In-situ Raman spectra of dissolved silica species in aqueous fluids to 900 °C and 14 kbar
- Quetzalcoatlite: A new octahedral-tetrahedral structure from a 2 × 2 × 40 μm3 crystal at the Advanced Photon Source-GSE-CARS Facility
- Bonding and dynamics of Mg in pyrope: a theoretical investigation
- Structure of a new Al-rich phase, [K, Na]0.9[Mg, Fe]2[Mg, Fe, Al, Si]6O12, synthesized at 24 GPa
- Core level electron binding energies of realgar (As4S4)
- Oxidation of {100} and {111} surfaces of pyrite: Effects of preparation method