Crystal Structure and Magnetic Properties of BiMn1 – xFexO3 (x ≤ 0.4) Solid Solution

Abstract

The crystal structure and magnetic properties of BiMn_1–xFe_xO₃ (x ≤ 0.4) solid solutions obtained by solid-phase reactions under high pressure have been studied by neutron and X-ray diffraction and magnetometry methods. The substitution of manganese ions with iron ions is shown to lead to a concentration phase transition from a monoclinic (C2/c space group) to an orthorhombic (Pnma space group) structure; the region of the two-phase structural state corresponds to the concentration range 0.2 ≤ x ≤ 0.4. Solid solutions with chemical compositions corresponding to the morphotropic phase boundary are characterized by the absence of long-range magnetic ordering, while at temperatures below ~80 K spontaneous magnetization is observed, reaching ~10–20 electromagnetic units/g at T = 5 K. The nature of the ferromagnetic component of the magnetic structure in compositions with a two-phase structural state is discussed along with the relationship between the structural state of solid solutions in the region of the morphotropic phase boundary and their magnetic properties.