In situ structure determination of the high-pressure phase of Fe3O4

The crystal structure of a high-pressure Fe3O4 phase was determined by in s itu X-ray diffraction measurements at high pressure and temperature, using an imaging plate detector and monochromatic synchrotron X-radiation. The hi gh-pressure phase has the Pbcm space group (CaMn2O4-type structure) with ce ll parameters a = 2.7992(3) Angstrom, b = 9.4097(15) Angstrom, and c = 9.48 32(9) Angstrom at 23.96 GPa and 823 K. Fe3+ occupies an octahedral site and Fe2+ is in an eightfold-coordinated site described as a bicapped trigonal prism. The high-pressure CaMn2O4-type Fe3O4 phase is about 6.5% more dense than the spinel form at 24 GPa.