Single-Crystal X-ray Diffraction on the Structure of (Al,Fe)-bearing Bridgmanite in the Lower Mantle

Abstract

12 Here we have performed single-crystal X-ray diffraction (SCXRD) experiments on two high-13 quality crystal platelets of (Al,Fe)-bearing bridgmanite 14 (Mg 0.88 Fe 3+0.065 Fe 2+0.035 Al 0.03 )(Al 0.11 Si 0.90 )O 3 (Fe10-Al14-Bgm) up to 64.6(6) GPa at room 15 temperature in a Boehler-Almax type diamond anvil cell. Refinements on the collected SCXRD 16 patterns reveal reliable structural information of single-crystal Fe10-Al14-Bgm, including unit-17 cell parameters, atomic coordinates, and anisotropic displacement parameters. Together with 18 Mössbauer and electron microprobe analyses, our best single-crystal refinement model indicates 19 that our sample contains ~6.5 mol% Fe 3+ , 3.5 mol% Fe 2+ , and 3 mol% Al 3+ in the large pseudo-20 dodecahedral site (A site), and ~11 mol% Al 3+ in the small octahedral site (B site). This may 21 indicate that Al 3+ in bridgmanite preferentially occupies the B site. Our results show