Iron phases at high pressures and temperatures: Phase transition and melting
-
S.K. Saxena
und
L.S. Dubrovinsky
Abstract
Based on an in situ X-ray study of Fe and a review of the available data, we propose the following triple-points in the Fe phase diagram-the hexagonal closest packed (HCP), face-centered cubic (FCC), and the b phase: P = 40 (4) GPa at T = 1550 (100) K, the b-phase-FCC-melt; P = 60 (10) GPa at T = 2600 (100) K. We define the stability of b phase from a combination of new X-ray results on externally heated Fe between pressures of 37 to 300 GPa, as well as the previous data on externally heated and laser-heated samples. X-ray data on externally heated Fe, without any pressure medium, confirms the double hexagonal closest packed (DHCP) structure for the b phase. The HCP-b phase boundary has a very small negative dP/dT indicating the similarity of physical properties (molar volume, thermal expansion, and bulk modulus) between the two phrases, but a higher entropy and enthalpy for the β phase
© 2015 by Walter de Gruyter Berlin/Boston
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Artikel in diesem Heft
- Thermal expansivity of mantle relevant magnesium silicates derived from vibrational spectroscopy at high pressure
- Differential laser-interferometer for thermal expansion measurements
- New diamond anvil cells for gigahertz ultrasonic interferometry and X-ray diffraction
- Elasticity measurement of silica glass under gas pressure
- Sound velocities of wadsleyite b-(Mg0.88Fe0.12)2SiO4 to 10 GPa
- Sound velocities and elastic properties of g-Mg2SiO4 to 873 K by Brillouin spectroscopy
- Harmonic and anharmonic properties of spinel MgAl2O4
- The MD simulation of the equation of state of MgO: Application as a pressure calibration standard at high temperature and high pressure
- Ab initio structure of MgSiO3 ilmenite at high pressure
- Thermoelasticity of silicate perovskites and magnesiowüstite and its implications for the Earth’s lower mantle
- Thermodynamic functions at zero pressure and their relation to equations of state of minerals
- Accuracy of equation-of-state formulations
- Extrapolation of lower mantle properties to zero pressure: Constraints on composition and temperature
- Constraints on the P-V-T equation of state of MgSiO3 perovskite
- Structure analysis and stability field of β-iron at high P and T
- Iron phases at high pressures and temperatures: Phase transition and melting
- Calculated melting curves for phases of iron
- Grüneisen parameter of e-iron up to 300 GPa from in-situ X-ray study
- Grüneisen parameters and isothermal equations of state
