Electron density distribution in the alloy Mn5Si3

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Abstract
The electron density distribution in the intermetallic compound Mn5Si3 has been investigated by using integrated intensity measurements of about 72% of all Bragg reflections with sin θ/λ less than 1·26 Å−1. The reflections were measured using an automatic diffractometer and monochromatic AgKå radiation. The intensities were put on an absolute scale with respect to the absolute values of the (h0.0) scattering amplitudes which were measured with a large crystal in the symmetrical Bragg position. The absorption and extinction are both small because of the short wavelength and quantitative corrections have been made. The spherical and aspherical parts of the electron density distributions have been analysed separately and it is shown that the radial parts of the electron density around the two non-equivalent manganese sites differ significantly. The distributions around both the Mn11 and Si sites show significant departures from spherical symmetry which can be satisfactorily accounted for in terms of anisotropic thermal vibrations. The anisotropic temperature factors deduced are shown to agree within experimental error with those obtained for the nuclear vibrations from a limited neutron diffraction investigation.