Untersuchungen zur kristallstruktur und magnetischen struktur des ferberits FeWO4

Abstract

The structure parameters of ferberite FeWO4 were determined from x-ray and neutron-diffraction measurements. The least-squares refinement method was used to refine the parameters obtained from a three-dimensional difference Fourier synthesis. The metal ions (Fe2+ and W6+) occupy one half of the octahedral holes in a slightly deformed hexagonal closest-packed lattice of oxygen atoms. This structure is identical to the structure of NiW04 other than for small parameter variations. It was shown by the neutron-diffraction measurements at liquid helium temperature (4.2°K) that the ferromagnetically planes (100) were antiferro-magnetically ordered parallel along the x axis. All of the moments lie parallel in the plane (010). They build an angle of 29° with the x axis and are not perpendicular to any of the octahedral faces. The magnitude of the moment (2.19 μB) for a Fe2+ ion corresponds approximately to the four unpaired electrons of the Fe2+ ions when one considers only the spin components. The antiferromagnetic transition temperature was found to be 66°K for ferberite. © 1967, Walter de Gruyter. Alle Rechte vorbehalten.