Phonon Density of States and Compression Behavior in Iron Sulfide under Pressure

Argonne National Laboratory, Lemont, Illinois, United States
Physical Review Letters (Impact Factor: 7.51). 12/2004; 93(19):195503. DOI: 10.1103/PhysRevLett.93.195503
Source: PubMed


We report the partial phonon densities of states (DOS) of iron sulfide, a possible component of the rocky planet's core, measured by the 57Fe nuclear resonant inelastic x-ray scattering and calculate the total phonon DOS under pressure. From the phonon DOS, we drive thermodynamic parameters. A comparison of the observed and estimated compressibilities makes it clear that there is a large pure electronic contribution in the observed compressibility in the metallic state. Our results present the observation of thermodynamic parameters of iron sulfide with the low-spin state of an Fe2+ ion at the high density, which is similar to the condition of the Martian core.

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    • "Fits to the data provide the curvature of the parabola defined by Equa tion 9, and with the known density, one can derive Debye sound velocities of 3.49(5) km/s for ambient conditions, 4.54(6) km/s for 50 GPa and 300 K, and 3.98( I) km/s for 55 GPa and 1500 K, where values in paranthesis represent standard errors. In a similar way, Debye sound velocities have been obtained for iron metal (Mao et al., 2001), Fe-Ni and Fe-Si alloys (Lin et al., 2003), Fe09jrO (Struzhkin et al., 2001), Fe3S (Lin et al., 2004a), FeHv (Mao et al., 2004b), and FeS (Kobayashi et al., 2004) under high pressure. Very recently, the same method was applied to measure "
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    ABSTRACT: We summarize recent developments of nuclear resonant spectroscopy methods, such as nuclear resonant inelastic X-ray scattering and synchrotron Mossbauer spectroscopy, and their uses for the geophysical sciences. The inelastic method provides specific vibrational information, for example, the phonon density of states, and, in combination with compression data, it permits the determination of sound velocities and Gruneisen parameters under high pressure and high temperature. The Mossbauer method provides hyperfine interactions between the resonant nucleus and electronic environment, such as isomer shifts, quadrupole splittings, and magnetic fields, which provide important information on valence, spin state, and magnetic ordering. Both methods use a nuclear resonant isotope as a probe and can be applied under high pressure and high temperature. The physical mechanism of nuclear resonant scattering and the specifics in applications to Earth materials are presented with reference to several high-pressure studies on iron-bearing compounds.
    Advances in High-Pressure Mineralogy, 04/2007: pages 157-174; Geological Society of America.
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    • "The phase stability and structural properties of high-pressure phases of FeS have been investigated by numerous previous studies (King and Prewitt 1982; Fei et al. 1995; Kusaba et al. 1998; Takele and Hearne 1999; Marshall et al. 2000; Kavner et al. 2001; Urakawa et al. 2004; Kobayashi et al. 2004). The stable phase of FeS under ambient conditions is troilite (FeS I), a superstructure of the NiAs structure. "
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