HR: 0800h
AN: MR11A-0912    [Abstracts]
TI: The Equation of State of Fe3P-iron phosphide to 54 GPa
AU: * Santillan, J D
EM: jsant@mit.edu
AF: University of California, Santa Cruz, Department of Earth Sciences 1156 High Street, Santa Cruz, CA 95064
AU: Williams, Q
EM: quentw@es.ucsc.edu
AF: University of California, Santa Cruz, Department of Earth Sciences 1156 High Street, Santa Cruz, CA 95064
AU: Scott, H P
EM: hpscott@iusb.edu
AF: Indiana University, South Bend, Department of Physics and Astronomy 345 Northside Hall, South Bend, IN 46634
AB: We have measured the volume and lattice parameters of end-member Fe3P-schreibersite in the diamond anvil cell to pressures of 54 GPa at 300 K. Samples of Fe3P were also laser heated to temperatures of ~2100 K at 50 GPa, and examined following thermal quench. No pressure-induced or quenchable temperature-induced phase transitions are observed over the conditions of this study. Our pressure-volume data were fit to a 2nd-order Birch Murnaghan equation of state, yielding a best-fit isothermal bulk modulus, K0T, of 190 ñ 5 with an assumed of 4; fit to a 3rd-order EOS yielded a K0T of 252 (ñ 15) GPa with a dK/dP of 1.0 (ñ 0.6). The wide stability range of the tetragonal Fe3P-structure and its ubiquity in iron-rich meteorites make schreibersite the most likely phase by which P was originally incorporated in deep planetary interiors. The moderately enhanced bulk modulus of this P-bearing alloy relative to pure iron could partially compensate for a bulk modulus depression induced by other possible lighter alloying components of planetary cores, such as sulfur.
DE: 3919 Equations of state
DE: 3924 High-pressure behavior
DE: 3954 X ray, neutron, and electron spectroscopy and diffraction
DE: 1015 Composition of the core
SC: Mineral and Rock Physics [MR]
MN: 2004 AGU Fall Meeting