Crystal structure and magnetic properties of Bi1-xSmxFeO3 ceramics across the phase boundary: effect of high pressure

Abstract

The solid solutions Bi_1-xSm_xFeO₃ with chemical composition across the morphotropic phase boundary region specific for rhombohedral - orthorhombic structural transition were investigated by X-ray diffraction, electron microscopy and magnetometry. Structural measurements showed a concentration driven transition from the single phase rhombohedral structure to the single phase nonpolar orthorhombic structure through the formation of antipolar orthorhombic phase which coexists with the rhombohedral phase in the compounds with x < 0.15 followed by a coexistence with nonpolar orthorhombic phase in the compounds with x <= 0.18. Application external pressure provides a stabilization of the orthorhombic phase, viz. the polar rhombohedral phase diminishes and transforms to the anti-polar orthorhombic phase, while the anti-polar orthorhombic phase transforms to the non-polar orthorhombic phase. Magnetic properties of the compounds subjected to external pressure demonstrate an increase in the magnetization of the compounds having dominant rhombohedral phase, wherein coercivity significantly increases, while the spontaneous magnetization remains nearly constant.