@article{Li2026, 
author = {Zhanpeng Li and Yangda Dong and Qihang Tang and Ting Zheng and Jiagang Wu},
title = {Defect-engineered internal bias field enables highly efficient strain enhancement in lead-free BF-BT ferroelectric ceramics},
year = {2026},
journal = {Journal of Materiomics},
volume = {12},
number = {4},
keywords = {Defect engineering, Bismuth ferrite–barium titanate, Internal bias field electric-field-induced strain},
url = {https://www.sciopen.com/article/10.1016/j.jmat.2026.101220},
doi = {10.1016/j.jmat.2026.101220},
abstract = {Defect engineering has been widely explored as an effective route to modulate the electromechanical response of piezoelectric ceramics. However, achieving a high strain gain per defect design is often constrained by the competition between bias enhancement and defect-induced pinning. Here, we systematically investigate the defect-mediated electromechanical behavior of Mn-doped BiFeO3–BaTiO3-based ceramics with controlled defect concentrations. It is demonstrated that introducing an appropriate level of B-site aliovalent Mn dopants effectively amplifies the internal bias field while preserving ferroelectric switch ability leading to a pronounced bias-assisted strain amplification. In the optimal composition (x = 0.005), the strain increases from 0.02% to 0.23% at 3 kV/mm and from 0.06% to 0.36% at 4 kV/mm, corresponding to ~1050% and ~500% enhancements, respectively and a high large-signal piezoelectric coefficient d33* ≈ 900 pm/V. Structural and electrical analyses reveal that low Mn doping promotes the formation of dense nanodomains and facilitates the aging-induced ordering of defect dipoles, whereas excessive Mn incorporation induces strong lattice disorder and defect pinning, suppressing bias-field formation and strain response. These findings establish an effective defect–structure–bias-field design principle for enhancing electromechanical strain and strain-amplification efficiency in lead-free ferroelectric ceramics.}
}