Study Of Structural Ferroelectric And Storage Energy Density Properties Of Pvdf Bczt Nanocomposites

Abstract

Among the various lead-free ferro/piezoelectric ceramics, the calcium and zirconium doped barium titanate (BCZT) has been widely explored for its relaxor-type ferroelectric properties. The high value of Curie temperature, a high relative permittivity with low loss, good polarization, and large recoverable energy density in BCZT ceramics make these materials suitable for their use in dielectric energy storage capacitors. The BCZT ceramics in composition Ba(Zr0.2Ti0.8)O3-(Ba0.7Ca0.3)TiO3 are reported to show large piezoelectric properties, comparable to lead zirconium titanate (PZT) system. Piezoelectricity in polycrystalline ceramics was first observed in ferroelectric barium titanate (BT). After the discovery of key role of phase boundaries, morphotropic phase boundaries (MPB) and polymorphic phase transitions (PPT) in enhanced piezoelectric properties the different Ca+/Ba+ and Zr+/Ti+ ratios in BCZT were studied to investigate the morphotropic phase boundary (MPB) formation in crystal. The high permittivity and excellent ferro/piezoelectric properties of BCZT were obtained in the vicinity of MPB. The introduction of defect dipoles with Ca+ and Zr+ ions doping in the unit cell of BT inherit the structural and charge inhomogeneities which resulted in the formation of polar nanoregions (PNRs) in the crystal by interrupting the normal long range ferroelectric domain ordering. The formation of PNRs in BCZT leads to relaxor behavior in its ferroelectric properties which is characterized by slim ferroelectric PE hysteresis loop. The relaxor ferroelectrics due to their low hysteresis loss as indicated by small area under the slim PE loop are advantageous for applications in dielectric energy storage devices.