Porous sandwich structures based on BaZrTiO3–BaCaTiO3 ceramics for piezoelectric energy harvesting

Abstract

Abstract In this study, porous sandwich structures based on barium zirconate titanate–barium calcium titanate (BZT–BCT) ceramics are investigated for energy harvesting applications. To improve the piezoelectric energy harvesting performance, porous sandwich structures based on the BZT–BCT ceramics produced by the tape casting method are designed to be optimum materials with high piezoelectric charge coefficient and low dielectric constant. The dense and porous layer are made of BZT–BCT ceramic sheets and a mixture of BZT–BCT ceramic and polyvinylidene fluoride (PVDF), respectively. Here, the PVDF is a sacrificial material that is volatilized in the burnout process, which results in the formation of pores within the microstructure. Depending on the volume fraction of the porous layer, the BZT–BCT ceramics are manufactured in proportions ranging from 0% to 100 vol%. The 20 vol% of the porous layer exhibits the highest figure of merit (FOM) of 4.53 p.m.2/N. When the volume fraction of the porous layer exceeds 20 vol%, the FOM sharply decreases. The stored energy is calculated by measuring the output voltage on the external capacitor (1 μF) through the full-bridge circuit connected to the specimen. The energy density is calculated by dividing the stored energy by the sample area. The sample with a 20 vol% of the porous layer has an energy density of 7.29 μJ/cm2, which is the highest value attained.