Abstract
Diamond-anvil cell (DAC) high-pressure technique with in situ laser heating of a sample permits the determination of iron phase diagram to pressures reaching planetary cores. The DAC technique in combination with in situ x-ray study of iron has revealed the presence of at least one additional state of iron with possibly a double hexagonal closest packed (DHCP) structure given the name β. A review of the available data, indicates that in addition to the previously known triple points, the BCC( body-centered cubic)-HCP (hexagonal closest packed)-FCC (face centered cubic) and the β-BCC-FCC-melt, the following triple-points may exist in the iron phase diagram: the HCP-FCC-β: pressure (P) = 40 (4) GPa at temperature (T) = 1550 (100) K, the β-FCC-melt: P = 60 (10) GPa at T = 2600 (100) K. We define the stability of β-phase between pressures of 37 to 300 GPa at high temperatures. The HCP-β phase boundary has a small negative dP/dT indicating the similarity of physical properties (molar volume, thermal expansi n and bulk modulus) between the two but a higher entropy and enthalpy for the β-phase. The melting curve of iron has been determined quite reliably with the laser heated sample in the DAC to a pressure of about 80 gigapascal (GPa). The pressure range of melting has been extended to as high as 200 GPa but is not supported by shock-wave data and requires further studies for confirmation.
This is a preview of subscription content, log in via an institution to check access.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Preview
Unable to display preview. Download preview PDF.
References
Ahrens, T. J., Holland, K. G. and Chen, G. Q., 1997, in: Shock temperatures and the melting point of iron. CP429, Shock Compression of Condensed Matter, Schmidt, Dandekar and Forbes, eds. The American Inst. Phys.
Andrault, D., Fiquet, G., Kunz, M., Visocekas, F. and Hausermann, D., 1997, The orthorhombic structure of iron: An in-situ high-T/high-P structure solution and refinement. Science 278: 831.
Anderson, O. L. and Duba, A., 1997, Experimental melting of iron revisited. J. Geophys. Res. 102: 22659.
Anderson, O. L. and Isaak, D. G., 2000, Simulated melting curves for phases of iron. American Mineral. (in press).
Bass, J. D., Ahrens, T. J., Abelson, J. R. and Hua, T., 1990, Shock temperature measurements: New results for an iron alloy. J. Geophys. Res. 95:21757.
Boehler, R., 1986, The phase diagram of iron to 430 kbar, Geophys. Res. Lett., 13: 1153.
Boehler, R., Nicol, M. and Johnson, M. L., 1987, Internally-heated diamond-anvil cell: Phase diagram and P-V-T of iron in High-Pressure Research in Mineral Physics, Geophys.Monogr. Ser., vol. 39, M. H. Manghnani and Y. Syono eds., TERRAPUB, Tokyo/AGU, Washington DC.
Boehler, R., 1993, Temperatures in the Earth’s core from melting-point measurements of iron at high static pressures, Nature, 363:534.
Boehler, R., von Bargen, N. and Chopelas, A., 1990, Melting, thermal expansion, and phase transition of iron at high pressures, J. Geophys. Res., 95: 21731.
Brown, J. M. and McQueen, R. G., 1986, Phase transitions, Grüneisen parameters and elasticity for shocked iron between 77 GPa, J. Geophys. Res., 91: 7485.
Chen, G.Q and Ahrens, T.J. 1995. Equations of state of a, ε and liquid iron and iron’s melting curve -thermodynamic calculations. Geophys. Res. Lett., 22,21–24.
Chen, G.Q. and Ahrens, T. 1996. High-pressure melting of iron: new experiments and calculations. Phil. Trans. R. Soc. Lond. A, 354: 1251.
Coates. P. B. (1981) Multi-valent pyrometry. Metrologia. V 17 103–109.
Dubrovinsky, L. S., Saxena, S. K., Lazor, P., 1997, X-ray study of iron with in-situ heating at ultra high pressures. Geophys.Res. Lett.24:1835.
Dubrovinsky, L.S., Saxena S. K, Tutti F., Rekhi S. and LeBehan T., 2000, In situ X-ray study of thermal expansion and phase transition of iron at multimegabar pressure. Phys. Rev. Lett (In press).
Dubrovinsky, L. S., Saxena, S. K., Lazor, P., 1998a, High-pressure and high temperature in situ x-ray diffraction study of iron and corundum to 68 GPa using internally heated diamond-anvil cell. Phys. Chem. Mineral. 25:434.
Dubrovinsky, L. S., Saxena, S. K., Lazor, P., 1998b, Stability of -iron: A new synchrotron x-ray study of heated iron at high pressures. European J. Mineralogy, 10: 43.
Dubrovinsky, L. S., Lazor, P., Saxena, S. K., Haggkvist, P., Weber, H.P., Le Bihan, T. and Hausermann, D.,1999, Study of laser heated iron using third generation synchrotron x-ray radiation facility with imaging plate at high pressures. Phys. Chem. Mineral., 26:539.
Fernández Guillermot, A. and Gustafson, P., 1985, An assessment of the thermodynamic properties and the (p,T) phase diagram of iron, High Temp.-High Press., 16: 591.
Funamori, N., Yagi, T. and Uchida, T., 1997, High-pressure and high-temperature in situ x-ray diffraction study of iron to above 30 GPa using MA8-type apparatus. Geophys. Res. Lett. 23:953.
Gallagher, K.G. and Ahrens, T.J., 1994, First measurements of thermal conductivity of griceite and corundrum at ultra high pressures and the melting point of iron (abstract), EOS Trans. Am. Geophys. Un., 15(Suppl.),653.
Jeanloz, R. and Kavner, A., 1996, Melting criteria and imaging spectroradiometry in laser-heated diamond-cell experiments. Phil. Trans. R. Soc. Lond. A, 354:1307
Larson, A.C. and Von Dreele, R.B., 1994, Los Alamos National Laboratory, LAUR, 86–748,
Lazor, P. and Saxena, S.K., 1996 , Discussion comment on melting criteria and imaging spectroradiometry in laser-heated diamond-cell experiments (by R. Jeanloz & A. Kavner), Phil. Trans. R. Soc. Lond. A, 354:1307.
Mao, H.K., Bell, P.M. and Hadidiacos, C., 1987, Experimental phase relations of iron to 360 kbar, 1400°C, determined in an internally heated diamond anvil apparatus, in High-Pressure Research in Mineral Physics, Geophys.Monogr. Ser., vol. 39, M. H. Manghnani and Y. Syono, eds., TERRAPUB, Tokyo/AGU, Washington DC, 1987.
Saxena, S.K., Shen, G., Lazor, P., 1993, Experimental evidence for a new iron phase and implications for Earth’s core, Science, 260, 1312–1314.
Saxena, S.K., Shen, G. and Lazor, P., 1994, Temperatures in Earth’s core based on melting and phase transformation experiments on iron, Science, 264,405–407.
Saxena, S.K., Dubrovinsky, L.S., Häggqvist, P., Cerenius, Y., Shen, G. and Mao, H.K., 1995, Synchrotron X-ray study of iron at high pressure and temperature, Science, 269: 1703.
Saxena, S.K., Dubrovinsky, L.S. and Häggkvist, P., 1996, X-ray evidence for the new phase ß-iron at high temperature and high pressure, Geophys. Res. Lett., 23:2441.
Shen, G. Mao, H. K., Hemley, R. J., Duffy, T. S., Rivers, M. L., 1998, Melting and crystal structure of iron at high pressures. Geophys. Res. Lett., 25:373.
Yoo, C. S., Holmes, N.C. and Ross, M., 1993, Shock temperatures and melting of iron at earth core conditions. Phys. Rev. Lett. 70: 3931.
Yoo, C.S., Akella, J., Campbell, A.J., Mao, H.K. and Hemley, R.J., 1995, Phase diagram of iron by in situ X-ray diffraction: Implications for Earth’s core, Science, 270:1473.
Author information
Authors and Affiliations
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2000 Springer Science+Business Media New York
About this chapter
Cite this chapter
Saxena, S.K., Dubrovinsky, L.S. (2000). Iron Phase Diagram at High Pressures and Temperatures. In: Meike, A., Gonis, A., Turchi, P.E.A., Rajan, K. (eds) Properties of Complex Inorganic Solids 2. Springer, Boston, MA. https://doi.org/10.1007/978-1-4615-1205-9_17
Download citation
DOI: https://doi.org/10.1007/978-1-4615-1205-9_17
Publisher Name: Springer, Boston, MA
Print ISBN: 978-1-4613-5440-6
Online ISBN: 978-1-4615-1205-9
eBook Packages: Springer Book Archive