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 approximate to 0.16 and "commensurate-incommensurate" within the orthorhombic phase at x approximate to 0.18. In contrast, in the Bi1-xPrxFeO3 series, the polar rhombohedral phase transforms into an antipolar orthorhombic one at x >= 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. (C) 2011 Elsevier Ltd. All rights reserved.