Structural stability and magnetic properties of Bi1−xLa(Pr)xFeO3 solid solutions

In this work, X-ray diffraction data taken on Bi1−xLaxFeO3 solid solutions are used to verify the following structural phase transitions: “polar rhombohedral–antipolar orthorhombic” at x≈0.16x≈0.16 and “commensurate–incommensurate” within the orthorhombic phase at x≈0.18x≈0.18. In contrast, in the Bi1−xPrxFeO3 series, the polar rhombohedral phase transforms into an antipolar orthorhombic one at x≥0.13x≥0.13. The polar rhombohedral phase near the morphotropic phase boundary exhibits an isothermal transformation into an antipolar orthorhombic phase, though the transformation occurs much faster in the case of La-doped compounds. The incommensurate structural phase was not detected in Bi1−xPrxFeO3 solid solutions. The ternary structural phase diagram is constructed for (Bi,La,Pr)FeO3 systems. In addition, the polar rhombohedral phase exhibits a magnetic field-induced transition from the modulated antiferromagnetic state into a homogeneous weak ferromagnetic state whereas the antipolar phase is a weak ferromagnetic state in the absence of an external field.

► An commensurate–incommensurate phase transition occurs in Bi0.8La0.2−xPrxFeO3 series. ► A correlation between crystal structure and magnetic properties was confirmed. ► The rhombohedral phase of the compounds is associated with a modulated antiferromagnetic structure. ► Enhanced remanent magnetization is caused by antisymmetric exchange interactions.