Neutron-powder-diffraction study of the structure and magnetic properties of Nd2Fe14Si3

The crystal and magnetic structures of Nd2Fe14Si3 at room temperature were refined by Rietveld analysis of neutron-powder-diffraction data. It was found that silicon atoms occupy preferentially both 18 h and 18 f of Th2Zn17-type structure with occupancies 0.36 and 0.14, respectively. The Fe-Fe bond-lengths computed with the refined crystallographic parameters have optimum values, as compared with those of Nd2Fe17 compounds, which can explain well why the Curie temperature rises strongly when the unit cell volume reduces with the substitution of silicon for iron in Nd2Fe17.