Effective electromechanical properties and energy harvesting response in PMN-0.3PT/PDMS flexible piezoelectric composites: a combined experimental and theoretical study

In this work, lead magnesium niobate-lead titanate (PMN-0.3PT) and polydimethylsiloxane (PDMS)-based flexible piezoelectric-polymer composites are designd and developd for efficient mechanical energy harvesting through a combined experimental-theoretical approach. A solid-state reaction method was employed to synthesize PMN-0.3PT piezo-ceramic, which was subsequently used for the fabrication of v(r)-PMN-0.3PT/PDMS piezoelectric-polymer 0-3 composite with different volume fractions, v(r) = 0.03, 0.25, and 0.50 of PMN-0.3PT reinforcement. Uniformly distributed PMN-0.3PT particles were found to retain their structural symmetry across the volume fractions and are well adhered to the PDMS matrix. The effective electromechanical properties of the composites were measured and compared with model predictions employing the finite element method and Eshelby-Mori-Tanaka-based micromechanical models. Considering that flexibility is a critical design parameter, we propose a new figure-of-merit term that would consider both electromechanical conversion as well as the mechanical flexibility of the material. We show that at v(r) = 0.5, PMN-0.3PT/PDMS 0-3 composite yields an optimum combination of energy harvesting performance and flexibility. Our study further demonstrates that the orientation of the PMN-0.3PT particles does not significantly influence the effective elastic and dielectric properties at low and moderate PMN-PT content, attributed to the lower aspect ratio of the reinforcement particles. The piezoelectric charge coefficient showed small yet finite change with increasing reinforcement content. A maximum current density, 35 nA cm(-2), and electric field, 90 V cm(-1), was obtained with a cyclic compressive stress of 0.22 MPa (force, 50 N) at 5 Hz, in a piezoelectric generator, based on v(r) = 0.5.