Regensburg 2016 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 21: Microstructure and Phase Transformations I
MM 21.4: Vortrag
Dienstag, 8. März 2016, 12:30–12:45, H38
Pressure-induced spin transition of Fe2+ in magnesio-siderite solid solution and siderite studied by x-ray Raman scattering — •Christopher Weis1, Christian Sternemann1, Max Wilke2,3, Valerio Cerantola4, Christoph J. Sahle5, Georg Spiekermann2,6, Yury Forov1, Hendrik Rahmann1, and Metin Tolan1 — 1Fakultät Physik/DELTA, Technische Universität Dortmund, 44221 Dortmund, GER — 2GeoForschungsZentrum(GFZ), 14473 Potsdam, GER — 3Universität Potsdam, 14469 Potsdam, GER — 4Bayerisches Geoinstitut, 95440 Bayreuth, GER — 5ESRF, 38043 Grenoble Cedex 9, FRA — 6DESY, 22607 Hamburg, GER
Owing to the low solubility of carbon in Earth mantle silicate phases, carbonate minerals may form as evidenced by inclusions found in diamonds formed in the Earth’s mantle. Here, Siderite (FeCO3) forms a complete solid solution with magnesite (MgCO3). Pressure-induced high-spin (HS) to low-spin (LS) transitions of such carbonates at conditions of the inner Earth and the associated change of its magnetic properties largely influences the materials characteristics such as sound velocity and density. In contrast to diffraction experiments, high-pressure optical Raman studies found indication for the coexistence of HS and LS state in a transition range in siderite as well as in the solid solutions. We investigated the spin transition of a siderite and magnesio-siderite single crystal for pressures up to 50 GPa using diamond anvil cell by x-ray Raman scattering at the iron M2,3-edge and L2,3-edge. The course of the spin transition will be discussed and confronted with optical Raman, x-ray emission and Mössbauer studies.