Journal of Synchrotron Radiation

Volume 12, Part 5 (September 2005)

SXD at Mbar pressures

J. Synchrotron Rad. (2005). 12, 637-641 [ doi:10.1107/S0909049505020741 ]

X-ray emission spectroscopy with a laser-heated diamond anvil cell: a new experimental probe of the spin state of iron in the Earth's interior

J.-F. Lin, V. V. Struzhkin, S. D. Jacobsen, G. Shen, V. B. Prakapenka, H.-K. Mao and R. J. Hemley

Abstract: Synchrotron-based X-ray emission spectroscopy (XES) is well suited to probing the local electronic structure of 3d transition metals such as Fe and Mn in their host phases. The laser-heated diamond anvil cell technique is uniquely capable of generating ultra-high static pressures and temperatures in excess of 100 GPa and 3000 K. Here X-ray emission spectroscopy and X-ray diffraction have been interfaced with the laser-heated diamond cell for studying the electronic spin states of iron in magnesiowüstite-(Mg_0.75,Fe_0.25)O and its crystal structure under lower-mantle conditions. X-ray emission spectra of the ferrous iron in a single crystal of magnesiowüstite-(Mg_0.75,Fe_0.25)O indicate that a high-spin to low-spin transition of ferrous iron occurs at 54 to 67 GPa and 300 K and the ferrous iron remains in the high-spin state up to 47 GPa and 1300 K. This pilot study points to the unique capability of the synchrotron-based XES and X-ray diffraction techniques for addressing the issue of electronic spin transition or crossover in 3d transition metals and compounds under extreme high-P-T conditions.

Keywords: X-ray emission spectroscopy; laser-heated diamond cell; electronic spin state; magnesiowüstite; high pressure.