The thermal equation of state of FeTiO[subscript 3] ilmenite based on in situ X-ray diffraction at high pressures and temperatures

Journal Article · Fri Nov 12 04:00:00 EST 2010 · Am. Mineral.

DOI:https://doi.org/10.2138/am.2010.3410· OSTI ID:1002862

Tronche, E J; Van Kan Parker, M; De Vries, J; Wang, Y; Sanehire, T; Li, J; Chen, B; Gao, L; Klemme, S; McCammon, C A; Van Westerenen, W ^[1]

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1. CIT

We present in situ measurements of the unit-cell volume of a natural terrestrial ilmenite (Jagersfontein mine, South Africa) and a synthetic reduced ilmenite (FeTiO{sub 3}) at simultaneous high pressure and high temperature up to 16 GPa and 1273 K. Unit-cell volumes were determined using energy-dispersive synchrotron X-ray diffraction in a multi-anvil press. Moessbauer analyses show that the synthetic sample contained insignificant amounts of Fe{sup 3+} both before and after the experiment. Results were fit to Birch-Murnaghan thermal equations of state, which reproduce the experimental data to within 0.5 and 0.7 GPa for the synthetic and natural samples, respectively. At ambient conditions, the unit-cell volume of the natural sample [V{sub 0} = 314.75 {+-} 0.23 (1{sigma}) {angstrom}{sup 3}] is significantly smaller than that of the synthetic sample [V{sub 0} = 319.12 {+-} 0.26 {angstrom}{sup 3}]. The difference can be attributed to the presence of impurities and Fe{sup 3+} in the natural sample. The 1 bar isothermal bulk moduli K{sub T0} for the reduced ilmenite is slightly larger than for the natural ilmenite (181 {+-} 7 and 165 {+-} 6 GPa, respectively), with pressure derivatives K{prime}{sup 0} = 3 {+-} 1. Our results, combined with literature data, suggest that the unit-cell volume of reduced ilmenite is significantly larger than that of oxidized ilmenite, whereas their thermoelastic parameters are similar. Our data provide more appropriate input parameters for thermo-chemical models of lunar interior evolution, in which reduced ilmenite plays a critical role.

• Research Organization: Advanced Photon Source (APS), Argonne National Laboratory (ANL), Argonne, IL (US)
• Sponsoring Organization: USDOE
• OSTI ID: 1002862
• Journal Information: Am. Mineral., Journal Name: Am. Mineral. Journal Issue: (11-12) ; 11, 2010 Vol. 95; ISSN AMMIAY; ISSN 0003-004X
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

43 PARTICLE ACCELERATORS
EQUATIONS OF STATE
ILMENITE
IMPURITIES
SYNCHROTRONS
X-RAY DIFFRACTION