2014/11/17 by Alberto Biancoli, Chris M. Fancher, Jacob L. Jones +1 · 1 citation
Engineering · Materials Science · Physics and Astronomy · #Composite Material Mechanics #Dielectric #Dielectric response #Ferroelectric and Piezoelectric Materials #Ferroelectricity #Flexoelectricity #Metamaterial #Nanoscopic scale #Nonlocal and gradient elasticity in micro/nano structures #Piezoelectricity #Polarization (electrochemistry) #Symmetry breaking #cond-mat.mtrl-sci
paper · pdf · doi:10.1038/nmat4139
published as Nat Mater, vol. 14, p. 224, 2015 · typo corrected
openalex publication_date 2014/11/17 · openalex created_date 2016/06/24 · arxiv created 2017/07/16 · arxiv updated 2017/07/18 · openalex updated_date 2026/08/05
A centrosymmetric stress cannot induce a polar response in centric materials, piezoelectricity is, for example, possible only in non-centrosymmetric structures. An exception is meta-materials with shape asymmetry, which may be polarized by stress even when the material is centric. In this case the mechanism is flexoelectricity, which relates polarization to a strain gradient. The flexoelectric response scales inversely with size, thus a large effect is expected in nanoscale materials. Recent experiments in polycrystalline, centrosymmetric perovskites [e.g., (Ba,Sr)TiO3] have indicated values of flexoelectric coefficients that are orders of magnitude higher than theoretically predicted, promising practical applications based on bulk materials. We show that materials with unexpectedly large flexoelectric response exhibit breaking of the macroscopic centric symmetry through inhomogeneity induced by the high temperature processing. The emerging electro-mechanical coupling is significant and may help to resolve the controversy surrounding the large apparent flexoelectric coefficients in this class of materials.