Flexure mode flexoelectric piezoelectric composites

We present a flexure mode composite design to generate steep transverse strain gradient to exploit large flexoelectric coefficient mu(1122) of (Ba, Sr)TiO3 (BST) ceramics. Very strong direct piezoelectric effect was observed in composites due to the flexoelectricity. In a single unit composite, sharp low frequency (<300 Hz) mechanical resonance leads to high effective d(33) > 2000 pC/N as the result of enhancement of strain gradient at resonance. Giant nonresonance d(33) well beyond piezoelectric single crystal about 4350 pC/N was measured at a temperature around Curie temperature of BST ceramic in a six unit three layer composite. (C) 2009 American Institute of Physics. [doi: 10.1063/1.3262495]