Anisotropy breaking in high level piezoelectric energy harvesting

Abstract

This study focused on mechanical energy harvesting and particularly on the difference between low and high levels of stress and electric fields. Energy conversion abilities were assessed through Ericsson cycle involving the application and release of electric field and stress at different phases of the cycle. The investigation focused on PMN-27PT single crystals known for their exceptional piezoelectric coefficient. Different crystal directions were examined through both experimentation and modeling using the Landau–Devonshire theory. Results unveiled a significant contrast between low and high-stress regimes. With low-level energy harvesting, orientation dependence of the energy density follows the $d_{33}$ piezoelectric coefficients symmetry, which is highly dependent on the crystal direction. However, our results under high levels indicated a more complex behavior caused by such conditions, yielding a more homogeneous energy distribution. Experimental assessments align well with modeling ones, confirming the unique response of ferroelectric materials when nonlinearities of polarization are involved.