Fe3+ -hosting carbon phases in the deep Earth

High-efficiency X-ray emission spectroscopy of cold-compressed Fe2O3and laser-heated pressurized FeCO3using a von Hámos spectrometer

“…In situ spin-state imaging of laser-heated FeCO 3 shows a spatially separated spin-state distribution of LS in the unheated and HS in the heated area of the sample, likely due to a decomposition of FeCO 3 into Fe 4 C 3 O 12 and Fe 4 C 4 O 13 . 29 The spin-state development of Fe 2 O 3 shows a decrease in IAD value in the z-phase with a signicant further drop at 75 GPa, i.e., in the Q-phase. The IAD value in the z-phase of 40% of the a-phase's value is likely based on a symmetry reduction from octahedral to trigonal-prismatic coordination on the HS site.…”

“…At 57 GPa the maxima of the pre-edge region are almost completely dispersing with the incident energy, except for a small energy region at the onset of the pre-edge region. Recently Albers et al 29 and Kaa et al 30 have shown experimentally, that both phases are in HS state. The ndings in this study are in accordance with the spin changes for laser-heated FeCO 3 .…”

“…Spin-state imaging 29 was performed in situ on laser-heated FeCO 3 at 75 GPa. The sample was heated to 2800 ± 300 K on one side.…”

“…21,[35][36][37][38][39][40][41] Recently, it has been shown experimentally that in both phases iron is in HS state at lower mantle pressure and temperature. 29,30 Fe 2 O 3 is an ideal showcase to discuss the capabilities of this setup for samples under cold compression. While Badro et al 26 presented the rst measurements of Kb 1,3 and vtc emission from Fe 2 O 3 under pressure, nding a HS to LS transition and a bond length change indicated by Kb ′′ intensity, more detailed studies are scarce.…”

“…21,35–41 Recently, it has been shown experimentally that in both phases iron is in HS state at lower mantle pressure and temperature. 29,30…”