An electron density residual study of α-ferric oxide

The residual electron density distribution in α-ferric oxide (Fe203; natural hematite) has been studied with single-crystal X-ray diffraction methods. A residual electron density double peak of 0.55 Å height is situated along the c-axis between face-sharing Feʹs, indicating metal-metal interaction. Residuals suggesting d-electrons were found around Fe. There are also interstitial residuals arranged around Fe hexagonally in a plane perpendicular to the c-axis. These features conform rather to directions related to the Fe neighbors than the coordinated oxygens. [393 equivalent-averaged reflexions, R values; conventional refinement with harmonic parameters: 0.0088, with scattering factor refinement: 0.0069; incorporation of anharmonic parameters did not lower the R value significantly.]