Piezoelectric Actuation Mechanism Involving Extrinsic Nano-domain Dynamics in Lead-free Piezoelectrics.

Piezoelectric materials play a key role in applications, while there are physically open questions. The physical origin of piezoelectricity is understood as the sum of contributions from intrinsic effects on lattice dynamics and those from extrinsic effects on ferroic-domain dynamics, but there is an incomplete understanding that all but intrinsic effects are classified as extrinsic effects. Therefore, the accurate classification of extrinsic effects is important to understand the physical origin of piezoelectricity. BiFeO 3 -BaTiO 3 are considered promising alternative lead-based materials. In this work, we utilize high-energy synchrotron X-ray diffraction to measure the response of BiFeO 3 -BaTiO 3 piezoelectrics and intrinsic/extrinsic contribution to electric fields. It is found to crystal structure and intrinsic/extrinsic contribution using the analysis involving structure refinement with various structural model and micromechanics-based calculations that Bi 3+ ion disordering at A-site in BiFeO 3 -BaTiO 3 system are important for realization of piezoelectricity and nano-domains. Here, we have suggested that the extrinsic effect on the rearrangement of nano-domains. The nano-domains, which is formed by locally distorted structure around A-site by Bi ion disordering, can significantly deform the material in BiFeO 3 -BaTiO 3 system, which contributes to the piezoelectric actuation mechanism apart from the extrinsic effect on ferroic-domain dynamics. Bi ion disordering plays an important role in realizing piezoelectricity and nano-domains and can provide essential material design clues to develop next-generation Bi-based lead-free piezoelectric ceramics using the control of disordered direction or off-centering displacement. This article is protected by copyright. All rights reserved.