Nano-to-micro polarization switching and electromechanical mechanisms in lead-free bismuth ferrite have shown opportunities in nonvolatile logic and optoelectronic applications. This report highlights improved ferroelectric polarization switching and electromechanical responses in (Nd, Mn) co-doped BiFeO3 ceramics via modulation of the B-site Mn substitution. The out-of-plane piezoresponse hysteresis loops reveals enhanced local polarization and electromechanical strain with increasing B-site Mn substitution. The B-site Mn substitution increases lattice distortion (or octahedral tilt) in rhombohedral R3c unit cell, confirmed by the enhanced ½(000)c superlattice electron diffraction. Average size of polar nano-regions (PNRs) and dielectric permittivity were also increased as Mn content increases. The synchrotron X-ray absorption spectra reveal a Mn3+ → Mn4+ valence shift and modulated orbital hybridizations between the O 2p and cation's orbitals (Fe 3d and Bi 6 s(p)), which are critical factors for the improved polarization and dielectric responses.
|Number of pages||11|
|Journal||Materials Science and Engineering B: Advanced Functional Solid-state Materials|
|Publication status||Published - Jul 2021|
- Dielectric permittivity
- Orbital hybridization
- Polar nano-regions
- Polarization switching