We present a critical review that encompasses the fundamentals and state-of-the-art knowledge of barium titanate-based piezoelectrics. First, the essential crystallography, thermodynamic relations, and concepts necessary to understand piezoelectricity and ferroelectricity in barium titanate are discussed. Strategies to optimize piezoelectric properties through microstructure control and chemical modification are also introduced. Thereafter, we systematically review the synthesis, microstructure, and phase diagrams of barium titanate-based piezoelectrics and provide a detailed compilation of their functional and mechanical properties. The most salient materials treated include the (Ba,Ca)(Zr,Ti)O3, (Ba,Ca)(Sn,Ti)O3, and (Ba,Ca)(Hf,Ti)O3 solid solution systems. The technological relevance of barium titanate-based piezoelectrics is also discussed and some potential market indicators are outlined. Finally, perspectives on productive lines of future research and promising areas for the applications of these ma...

BaTiO3-based piezoelectrics: Fundamentals, current status, and perspectives

Enhancing breakdown strength and energy storage performance of PVDF-based nanocomposites by adding exfoliated boron nitride

A simple and low cost in situ process has been developed to synthesize Fe2O3-Co3O4 nanoparticles (NPs) loaded poly(vinylidene fluoride) (PVDF) thin films. The electroactive β phase nucleation mechanism and the dielectric properties of the films have been investigated by X-ray diffraction spectroscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry and using an LCR meter. Results confirmed that the electroactive β phase crystallization in the PVDF matrix is due to the fast nucleating or catalytic effect of the in situ NPs. Homogenous dispersion of in situ Fe2O3-Co3O4 NPs in the polymer matrix leads to strong interfacial interaction between the NPs and the polymer resulting in enhanced β phase nucleation in PVDF and a large dielectric constant of the thin films. The observed variation in the electroactive β phase nucleation by NPs (Fe2O3-Co3O4) and the dielectric properties of the thin films have been explained on the basis of surface charge, size, geometrical shape and extent of agglomeration of the NPs in the polymer matrix.

Effect of in situ synthesized Fe2O3 and Co3O4 nanoparticles on electroactive β phase crystallization and dielectric properties of poly(vinylidene fluoride) thin films.

Lead-free piezoelectric compositions based on (Ba,Ca)(Zr,Ti)O3 have been reported to exhibit many piezoelectric properties similar to the conventionally used Pb(Zr,Ti)O3 materials, and have thus been attracting much attention as potential replacements for lead-based piezoceramics. However, there appears quite a wide variation in the reported piezoelectric properties of the BCZT ceramics, indicating that such properties may be sensitive to fabrication and processing methods. This paper reports an investigation of a wide range of processing factors, including composition (e.g. ratio of Ba(Zr,Ti)O3 to (Ba,Ca)TiO3), sintering conditions (temperature and cooling rate), particle size of the calcined ceramic powder, structure and microstructure (e.g. phase, lattice parameters, density and grain size), and their effect on the piezoelectric properties. For individual compositions, lattice constants and grain size, which are themselves dependent on the ceramic powder particle size and sintering conditions, have been shown to be very important in terms of optimising piezoelectric properties in these materials.

https://research.birmingham.ac.uk/portal/files/31757862/_BaCa_ZrTi_O3_Lead_free_Piezoelectric_Ceramics_The_Critical_Role_of_Processing_on_Properties_revised.pdf

(Ba,Ca)(Zr,Ti)O3 lead-free piezoelectric ceramics—The critical role of processing on properties

The search for electroceramic materials with enhanced ferro-pyro-piezoelectric properties and revealing the perovskite type structure has been the objective of a significant number of manuscripts reported in the literature. This has been usually carried out by proposing the synthesis and processing of new compounds and solid solution series. In this work, several methods to obtain ferro-pyro-piezoelectric families of materials featuring the well-known ABO3 perovskite structure (or related) such as BaTiO3, Ba1–xCaxTi1–yZryO3, (Bi0.5Na0.5)TiO3, (K0.5Na0.5)NbO3 and their solid solutions with different cations either in the A or B positions, are presented. For this kind of materials, the challenge for obtaining a single phase compound with a specific grain size and morphology and, most importantly, with the adequate stoichiometry, will also be discussed. The results reviewed herein will be discussed in terms of the tendency of working with softer conditions, i.e., lower temperature and shorter reaction times, also referred to as soft-chemistry.

/pdf/towards-lead-free-piezoceramics-facing-a-synthesis-challenge-2h9wxkplkp.pdf

Towards Lead-Free Piezoceramics: Facing a Synthesis Challenge

Effect of sintering temperature on dielectric, piezoelectric and ferroelectric properties of BZT–BCT 50/50 ceramics

Dielectric properties of 0.25(BZT–BCT)–0.75[(1 − x)PVDF–xCCTO] (x = 0.02, 0.04, 0.06, 0.08 and 0.1) composites for embedded capacitor applications

Enhanced dielectric and piezoelectric properties of BZT–BCT system near MPB

Enhancement of dielectric properties of 0.2[BZT-BCT]–0.8[(1 − x)epoxy–xCCTO] (x = 0.02, 0.04, 0.06, 0.08 & 0.1) composites for embedded capacitor and energy harvesting applications

P. Mishra

Papers

Effect of sintering temperature on dielectric, piezoelectric and ferroelectric properties of BZT–BCT 50/50 ceramics

Dielectric properties of 0.25(BZT–BCT)–0.75[(1 − x)PVDF–xCCTO] (x = 0.02, 0.04, 0.06, 0.08 and 0.1) composites for embedded capacitor applications

Enhanced dielectric and piezoelectric properties of BZT–BCT system near MPB

Enhancement of dielectric properties of 0.2[BZT-BCT]–0.8[(1 − x)epoxy–xCCTO] (x = 0.02, 0.04, 0.06, 0.08 & 0.1) composites for embedded capacitor and energy harvesting applications

Structural, dielectric and optical properties of [(BZT–BCT)-(epoxy-CCTO)] composites