Dielectric and piezoelectric properties of porous lead-free 0.5Ba(Ca0.8Zr0.2)O3-0.5(Ba0.7Ca 0.3)TiO3 ceramics

Abstract

Porous barium calcium zirconate titanate 0.5Ba(Ca0.8Zr0.2)O3-0.5(Ba0.7Ca0.3)TiO3 (BCZT) lead-free ferroelectric ceramics were fabricated via a burnt polymer spheres (BURPS) technique by introducing corn starch as the pore-forming agent. The effect of porosity on the microstructure, dielectric, and piezoelectric properties of the porous materials were investigated. An increase in porosity from 10 % to 25 % resulted in an increase in the hydrostatic charge coefficient (dh), which was 140 to 560 % higher than that of the dense BCZT material. An increase in porosity from 10 % to 25 % also lead to a decrease in relative permittivity that was 16.7% to 60.4% lower than the dense material. These two changes in properties provided a significant enhancement of the hydrostatic figure of merit (dh•gh) for the porous ceramic; for example the dh•gh of the 25 vol.% porous BCZT ceramic was 158 times more than the dense ceramic and demonstrates the potential of porous lead-free ferroelectrics for piezoelectric transducer devices. Reasons for the significant enhancement in piezoelectric performance of the porous ceramics are discussed. Highlights:ü Porous lead-free piezo-ceramics were fabricated by introducing pore-forming agents. ü An increase in porosity increased hydrostatic charge coefficient and decreased permittivity. ü Hydrostatic parameters gh and dh•gh of the porous ceramic were 140% to 560% higher than the dense material.

Porous ferroelectric materials for energy technologies: current status and future perspectives

“…6a, the TC increased slightly with an increase in porosity, which was attributed to stress relaxation near the pores. 122 A similar trend was also observed in freeze-cast porous PZT ceramics, 88 as shown in Fig. 6b.…”

“…The decrease in the piezoelectric coefficients can be ascribed to the reduced efficiency of the poling process, which leads to a reduced piezoelectric response 122 ; this stems from a decrease in the remnant polarization since due to the complex electric field distribution on porous ferroelectrics. The piezoelectric dij coefficients of porous ferroelectric ceramics are therefore usually lower than dense materials.…”

Factors affecting the piezoelectric performance of ceramic-polymer composites: A comprehensive review

“…Moreover, Zhang et al, [102] investigated the piezoelectric and dielectric properties of lead-free porous 0.5Ba(Ca0.8Zr0.2)O3-0.5(Ba0.7Ca0.3)TiO3 (BCZT) ceramics. They reported that the porosity decreased the relative permittivity while a denser material increased the permittivity.…”

Numerical investigation of sensing and energy harvesting performance of 0-3 and triply periodic minimal surface-based K0.475Na0.475Li0.05(Nb0.92Ta0.05Sb0.03)O3 and polyethylene piezocomposite: A comparative study

“…Lead is toxic and detrimental both to humans as well as to the environment, the use of lead-based piezoelectric material is discouraged these days, and search for several lead-free alternative materials is encouraged (Vaish, 2013;Vaish, 2013, 2014). Several lead-free piezoelectric materials, which are poled ferroelectric ceramics, have been reported in the literature such as (Maeder et al, 2004;Zhang et al, 2019). KNLNTS, due to its higher piezoelectric strain coefficient, is a promising lead-free piezoelectric material that can be used as an alternative to lead-based piezoelectric materials (Berger et al, 2005;Kwok et al, 2010) for sensing and energy harvesting applications.…”