A comparative study of field-induced domain switching and lattice strain was carried out by in situ electric-field-dependent high-energy synchrotron x-ray diffraction on a morphotropic phase boundary (MPB) and a near-MPB rhombohedral/pseudomonoclinic composition of a high-performance piezoelectric alloy $(1-x)\mathrm{PbTi}{\mathrm{O}}_3-\left(x\right)\mathrm{BiSc}{\mathrm{O}}_3$. It is demonstrated that the MPB composition showing large $d_{33}\sim 425pC/N$ exhibits significantly reduced propensity of field-induced domain switching as compared to the non-MPB rhombohedral composition $(d_{33}\sim 260pC/N)$. These experimental observations contradict the basic premise of the martensitic-theory-based explanation which emphasizes on enhanced domain wall motion as the primary factor for the anomalous piezoelectric response in MPB piezoelectrics. Our results favor field-induced structural transformation to be the primary mechanism contributing to the large piezoresponse of the critical MPB composition of this system.

• Received 5 June 2015
• Revised 4 February 2016

DOI:https://doi.org/10.1103/PhysRevB.93.104103