Ba3Fe2WO9−δ: Effect of oxygen non-stoichiometry on structural and magnetic properties

The magnetic and structural properties of oxygen-deficient perovskites with composition Ba3Fe2WO9−δ   (BFWO) have been systematically studied for two different oxygen contents corresponding to δ=0.00δ=0.00 and 0.550.55 in the chemical formula in order to determine and correlate their chemical composition, structural and magnetic properties. The evolution of nuclear and magnetic structures with temperature has been investigated by neutron powder diffraction. It was shown that at room temperature the stoichiometric compound (δ=0.00δ=0.00) adopts a hexagonal 6H-perovskite structure (space group P63/mmcP63/mmc). This phase, when heated at high temperature under a stream of Ar gas, transforms to an oxygen-deficient phase δ=0.55δ=0.55), which is an ordered cubic perovskite structure (space group Fm–3mFm–3m). The crystallographic and magnetic properties of the obtained phases are compared, and it is clear that the magnetic properties are significantly affected by oxygen non-stoichiometry. These changes of magnetic properties for such a slight decrease in oxygen content are interpreted as a result of structural transformations. Together with the experimental results based on neutron powder diffraction data a discussion of some aspects of the structural transformation (P63/mmc→Fm–3m) is presented.

Magnetic structure of the oxygen-deficient perovskite Ba3Fe2WO8.45.Figure optionsDownload as PowerPoint slide