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MM: Fachverband Metall- und Materialphysik

MM 17: Postersession I

MM 17.29: Poster

Montag, 16. März 2015, 18:00–20:00, Poster E

Pressure-induced spin transition of Fe²⁺ in siderite FeCO₃ studied by x-ray Raman scattering — •Christopher Weis¹, Christian Sternemann¹, Max Wilke², Valerio Cerantola³, Christoph J. Sahle⁴, Georg Spiekermann⁵, and Metin Tolan¹ — ¹Fakultät Physik/DELTA, Technische Universität Dortmund, 44221 Dortmund, Germany — ²Helmholtz-Zentrum Potsdam, German Research Centre for Geoscience (GFZ), 14473 — ³Bayerisches Geoinstitut, University of Bayreuth, 95440 Bayreuth, Germany — ⁴ESRF, 38043 Grenoble Cedex 9, France — ⁵Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany

Pressure-induced electronic and/or structural transitions of iron bearing compounds at conditions of the inner earth fundamentally affect the material’s properties, e.g. sound velocitiy and density. Siderite (FeCO₃) forms a complete solid solution with magnesite (MgCO₃). Owing to the low solubility of carbon in the mantle it is a candidate for carbon storage and a key mineral to understand the Earth’s carbon cycle. Lavina et al. [1] applied high-pressure x-ray diffraction to siderite and found a high-spin to low-spin transition to occur at 43-49 GPa with a sharp volume collapse of 10 % at a pressure of 44 to 45 GPa. We investigated changes in the electronic structure of a siderite single crystal for pressures up to 50 GPa using a Boehler-Almax diamond anvil cell with helium as pressure medium by x-ray Raman scattering at the iron M_2,3-edge and L_2,3-edge. The course of the spin transition up to 50 GPa is discussed by the observed spectral changes. [1] B. Lavina et al., Geophys. Res. Lett. 36, L23306 (2009)