Piezoelectric composite based on the enhanced flexoelectric effects

In this study, a piezoelectric composite is fabricated from a Ba0.67Sr0.33TiO3 (BST) composition and air, and measured at room temperature (24 degrees C) where the BST is in its paraelectric centric phase. The charge separation mechanism is flexoelectricity, driven by the strain gradient introduced by the pyramidal boundary shapes of each BST building unit of the composite. In spite of the macro (millimeter) dimensions of the building units that inhibit a steep strain gradient, the composite is sufficiently active to be measured by using a conventional Berlincourt d(33) meter. The measured values are in good agreement with expectation from the earlier measured flexoelectric coefficient mu(11) of the BST and the finite element simulation results of the strain gradient in the pyramid BST units.