BiFeO3 perovskites: theoretical and experimental investigations

Abstract

Bismuth ferrite (BiFeO3) is one of the most studied multiferroic system. BiFeO3 has been synthesized by controlled hydrothermal process, where the particles of small sizes and with high purity were obtained. Structural analysis showed that nonannealed powder can be perfectly fitted to rhombohedral space group R3c as αBiFeO3 phase. In addition, a structure prediction has been performed and 11 additional BiFeO3 modifications have been proposed. In the next phase, an ab initio optimization of predicted structures has been performed and the structure of the γphase has been elucidated. In addition, electronic and magnetic properties of BiFeO3 were investigated using combination of experimental and theoretical methods. Theoretical studies were performed using a full potential linearized augmented plane-waves plus local orbital (FP(L)APW+lo) method, based on density functional theory (DFT). HRTEM analysis confirmed existence of twin stacking faults, which are responsible for enhanced magnetic properties. EPR measurements suggested existence of electrons trapped by vacancies or defects, while magnetic behavior of synthesized material was investigated by SQUID.