Study of the B-site ion behaviour in the multiferroic perovskite bismuth iron chromium oxide

A simple, near-ambient pressure solid-state method was developed to nominally synthesize BiFe0.5Cr0.5O3. The procedure allowed the gram-scale production of multiferroic samples with appreciable purity and large amounts of Cr incorporation that were suitable for systematic structural investigation by neutron, X-ray, and electron diffraction in tandem with physical characterization of magnetic and ferroelectric properties. The rhombohedrally distorted perovskite phase was assigned to the space group R3c by way of X-ray and neutron powder diffraction analysis. Through a combination of magnetometry and muon spin relaxation, it is evident that there is magnetic ordering in the BFCO phase consistent with G-type antiferromagnetism and a TN ∼ 400 K. There is no clear evidence for chemical ordering of Fe and Cr in the B-site of the perovskite structure and this result is rationalized by density functional theory and bond valence simulations that show a lowered energy associated with a B-site disordered structure. ...