Porosity effect on the functional properties and energy harvesting performance of Ba_0.85Ca_0.15Ti_0.90Zr_0.10O₃ ceramics

Abstract

In this study, the effect of porosity on the structural and functional (dielectric, ferroelectric, nonlinear, and piezoelectric) properties in Ba0.85Ca0.15Ti0.90Zr0.10O3 ceramics was investigated. Various levels of microporosity in the range of 3% to 31 vol.% have been produced using poly(methyl methacrylate) microspheres as sacrificial templates. The structural investigation indicates a phase coexistence, as expected for this composition at room temperature. The maximum permittivity decreases with increasing porosity, from around 7000 (ceramic with 3 vol.% porosity) down to 3500 (ceramic with 31 vol.% porosity), and the Curie temperature shifts from 47 to 67°C when increasing porosity, related to the possible porosity‐induced structural and internal stress modifications. An enhanced piezoelectric response was found in the Ba0.85Ca0.15Ti0.90Zr0.10O3 ceramic with intermediate porosity around 18 vol.%, with the highest value of piezoelectric response of 470 pC/N and a figure of merit of 7.3 pm2/N. The optimum piezoelectric properties at the intermediate porosity level are related to the microstructural changes (pore shape and connectivity) and possible field‐induced structural modifications. The piezoelectric energy harvesting measurement results have shown the possibility of using Pb‐free porous ferroelectric materials in devices for energy harvesting applications.

Temperature-Dependent Ferroelectric Properties and Aging Behavior of Freeze-Cast Bismuth Ferrite–Barium Titanate Ceramics

“…The dielectric behavior aligns with that seen in dense ferroelectric ceramics albeit with slight perturbations in the Curie point. For example, an increase in the Curie point was reported in porous barium zirconium calcium titanate (BCZT) , and PZT ceramics, whereas a decrease was reported for porous 0.36BiScO 3 –0.64PbTiO 3 and barium calcium titanate. In some cases, no significant change in Curie point was observed as a function of pore fraction, e.g., in porous barium strontium titanate or barium zirconium titanate .…”