Achieving Large Switchable Polarization and Enhanced Piezoelectric Response in BiFeO3-PbTiO3 Solid Solution Ceramics

Perovskite materials based on BiFeO3-PbTiO3 (BFPT) solid solutions are promising for various applications thanks to the extremely large spontaneous polarization (P-s) and existence of multiferroic morphotropic phase boundary. For applications in piezoelectric and memory devices, complete switching of P-s is needed, which is hard to achieve practically. In this work, a simple modified mixed-oxide reaction method is developed allowing to prepare Dy- and Sm-modified BFPT ceramics with significantly improved properties. The MPB compositions demonstrate well-saturated ferroelectric hysteresis loops with large switchable remanent polarization of 60 mu C cm(-2) and enhanced piezoelectric properties with a large-signal piezoelectric coefficient d(33)* = 214 pm V-1 and a direct piezoelectric coefficient d(33) = 128 pC N-1, which is one and a half times larger than the best d(33) value reported for the BFPT ceramics so far. The Curie temperature reaches 539 degrees C, suggesting a potential for high-temperature applications. The domain structure is studied by piezoresponse force microscopy. It is found that the enhanced dielectric/piezoelectric properties are mainly due to polarization rotation/extension (intrinsic) mechanism, while the extrinsic contributions of the interphase and domain walls are virtually absent. The strategies for improvement of properties of BFPT and related materials are proposed.

Automated summary

A simple modified mixed-oxide reaction method was developed to prepare Dy- and Sm-modified BFPT ceramics with significantly improved properties, showing well-saturated ferroelectric hysteresis loops and enhanced piezoelectric properties suitable for high-temperature applications. The enhanced dielectric/piezoelectric properties were mainly attributed to intrinsic mechanisms of polarization rotation/extension, with minimal extrinsic contributions from interphase and domain walls.