Enhanced ferroelectric and piezoelectric properties of LaxBi(1−x)FeO3 ceramics studied by impedance spectroscopy

Multiferroic bismuth ferrite (BiFeO3, BFO) is one of the most promising high-temperature ferroelectric and piezoelectric materials due to a high Curie temperature (TC∼830 °C) if the enhancement of ferroelectricity and piezoelectricity can be realized. In this work, we introduced La (x=0.05-0.30) to BFO to change its crystal structure and obtained an enhanced Rhombohedral structure. The high pure LaxBi(1−x)FeO3 (LBFO) powders with refined grain size were prepared by microwave hydrothermal method, then the ceramics were sintered under microwave condition. The enhanced piezoelectric property results (d33=55-62pC·N−1) showed that La3+ could not only stable the Rhombohedral structure and form Metastable phase contributing to the piezoelectric effects at a special range of doping contents. The figure of dielectric property versus frequency indicated La3+ doped BFO ceramics could increase dielectric constant and reduce the loss. The values of bulk resistance (Rb) obtained from the intercept of semicircular arcs on the real axis (Z) at different temperatures decrease with the increasing of the doping contents. The Pr increased which could be ascribed to that the introduction of La could lead to the distortion of the crystal structure of BFO ceramics and the formation of more dipoles or short-range charge carriers. Finally, the M-H loops suggested that the Saturation magnetization and Coercive magnetic field LBFO ceramics was improved with increasing La contents.