Piezoelectric Mimicry of Flexoelectricity
Abdollahi, Amir (Universitat Politècnica de Catalunya)
Vásquez Sancho, Fabián (Institut Català de Nanociència i Nanotecnologia)
Catalan, Gustau (Institut Català de Nanociència i Nanotecnologia)

Data:	2018
Resum:	The origin of "giant" flexoelectricity, orders of magnitude larger than theoretically predicted, yet frequently observed, is under intense scrutiny. There is mounting evidence correlating giant flexoelectriclike effects with parasitic piezoelectricity, but it is not clear how piezoelectricity (polarization generated by strain) manages to imitate flexoelectricity (polarization generated by strain gradient) in typical beam-bending experiments, since in a bent beam the net strain is zero. In addition piezoelectricity changes sign under space inversion but giant flexoelectricity is insensitive to space inversion, seemingly contradicting a piezoelectric origin. Here we show that, if a piezoelectric material has its piezoelectric coefficient asymmetrically distributed across the sample, it will generate a nonzero bending-induced polarization impossible to distinguish from true flexoelectricity even by inverting the sample. The effective flexoelectric coefficient caused by piezoelectricity is functionally identical to, and often larger than, intrinsic flexoelectricity: our calculations show that, for standard perovskite ferroelectrics, even a tiny gradient of piezoelectricity (1% variation of piezoelectric coefficient across 1 mm) is sufficient to yield a giant effective flexoelectric coefficient of 1 μC/m, three orders of magnitude larger than the intrinsic expectation value.
Ajuts:	European Commission 308023 Ministerio de Economía y Competitividad MAT2016-77100-C2-1-P Ministerio de Economía y Competitividad SEV-2013-0295
Drets:	Tots els drets reservats.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Matèria:	Expectation values ; Flexoelectric coefficients ; Flexoelectricity ; Induced polarization ; Orders of magnitude ; Piezoelectric coefficient ; Strain gradients ; Three orders of magnitude
Publicat a:	Physical review letters, Vol. 121, Issue 20 (November 2018) , art. 205502, ISSN 1079-7114

DOI: 10.1103/PhysRevLett.121.205502

5 p, 445.5 KB

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