Effects of Fe 3d–O 2p and Bi 6sp–O 2p orbital hybridizations in Nd doped BiFeO3 ceramics

Abstract

Abstract This study highlights the importance of electronic hybridizations in the FeO6 octahedral distortion, structural evolution, magnetization, oxidation state and atomic bonding covalency in multiferroic (Bi1−xNdx)FeO3 (x = 0–0.10) ceramics as the system approaches the morphotropic phase boundary (MPB). The Rietveld-refinement analysis reveals reductions of bismuth deficiency, oxygen vacancies, and nonpolar Bi2Fe4O9 phase as Nd increases. The piezoresponse domain switching reveals a coexistence of polar ferroelectric rhombohedral and minor orthorhombic (nonpolar) phases. The piezoresponse ferroelectric polarization hysteresis loops are attributed to the reduced leaky conductivity in the Nd-doped compositions. The Fe K- and L2,3-edges synchrotron X-ray absorptions suggest a mixture of Fe3+ and Fe4+ valence states and reduction of the FeO6 octahedral distortion by the A-site Nd substitution. The oxygen K-edge synchrotron X-ray absorptions reveal that the hybridizations of the O 2p–Fe 3d and the O 2p–Bi 6sp orbitals were decreased with increasing Nd content.