HR: 1340h
AN: MR23B-0059    [Abstracts]
TI: New experimental evidence for simple phase behavior of iron and perovskite.
AU: * Boehler, R
EM: boe@mpch-mainz.mpg.de
AF: Max-Planck-Institut f.Chemie, Postfach 3060, Mainz Germany, 55020 Germany
AU: Japel, S L
EM: japel@mpch-mainz.mpg.de
AF: Max-Planck-Institut f.Chemie, Postfach 3060, Mainz Germany, 55020 Germany
AU: Errandonea, D
EM: daniel.errandonea@uv.es
AF: ICMUV, Universitat de Valencia, Moliner 50, Valencia, 46100 Spain
AU: Mezouar, M
EM: mezouar@esrf.fr
AF: ESRF, BP 220, Grenoble, 38043 France
AU: Benedetti, L R
EM: boe@mpch-mainz.mpg.de
AF: ESRF, BP 220, Grenoble, 38043 France
AB: Several recent X-ray measurements on heated iron have shown signs of new phases leading to a rather complicated phase diagram. It was suspected that the differences in the results were due to different experimental conditions. We measured X-ray diffraction patterns of laser heated iron under inert and hydrostatic conditions to 114 GPa and above its melting temperature. Only the fcc and hcp phases were observed. Fcc iron is stable to at least 68 GPa leading to a higher fcc-hcp-liquid triple point than previously reported from non-hydrostatic measurements. At higher pressures only hcp was observed making this phase again the strongest candidate for the solid-inner core. Natural enstatite-(Mg0.9Fe0.1)SiO3, heated at 107 GPa for 10 min. to 2000 K for the first time without a metal absorber and in an inert argon pressure medium yielded only the orthorhombic, well known perovskite structure. This pressure, not corrected for thermal pressure increase is higher that that reported in some studies where a phase change to the post-perovskite phase was observed for similar starting materials but under different experimental conditions.
DE: 3924 High-pressure behavior
DE: 3954 X-ray, neutron, and electron spectroscopy and diffraction
DE: 3994 Instruments and techniques
SC: Mineral and Rock Physics [MR]
MN: Fall Meeting 2005