Ferroelectrics as Smart Mechanical Materials.

Cordero-Edwards, Kumara; Domingo, Neus; Abdollahi, Amir; Sort, Jordi; Catalan, Gustau · Adv Mater · 2017

basic_science · Level V

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Abstract

The mechanical properties of materials are insensitive to space inversion, even when they are crystallographically asymmetric. In practice, this means that turning a piezoelectric crystal upside down or switching the polarization of a ferroelectric should not change its mechanical response. Strain gradients, however, introduce an additional source of asymmetry that has mechanical consequences. Using nanoindentation and contact-resonance force microscopy, this study demonstrates that the mechanical response to indentation of a uniaxial ferroelectric (LiNbO<sub>3</sub> ) does change when its polarity is switched, and use this mechanical asymmetry both to quantify its flexoelectricity and to mechanically read the sign of its ferroelectric domains.