Influence of Ferroelectric Filler Size and Clustering on the Electrical Properties of (Ag-BaTiO)-PVDF Sub-Percolative Hybrid Composites.

The paper presents a study concerning the role of ferroelectric filler size and clustering in the dielectric properties of 20%BaTiO-80%PVDF and of 20% (2%Ag-98%BaTiO)-PVDF hybrid nanocomposites. By finite element calculations, it was shown that using fillers with ε > 10 does not provide a permittivity rise in the composites and the effective dielectric constant tends to saturate to specific values determined by the filler size and agglomeration degree. Irrespective of the ferroelectric filler sizes, the addition of metallic ultrafine nanoparticles (Ag) results in permittivity intensification and the effect is even stronger if the metallic nanoparticles are connected to a higher degree with the ferroelectric particles' surfaces.

Optimization of Processing Steps for Superior Functional Properties of (Ba, Ca)(Zr, Ti)O Ceramics.

Lead-free piezoelectric ceramics with nominal composition at morphotropic phase boundary BaCaTiZrO (BCTZ) prepared by different processing routes and sintered either by conventional solid-state reaction or by spark plasma sintering (SPS) techniques were comparatively investigated to observe the role of structural modifications and of microstructures on the dielectric, ferroelectric, piezoelectric and electrocaloric responses. The ceramics presented relative densities from 75% to 97% and showed variations in their phase composition as a result of variable mixing and different synthesis and sintering parameters providing local compositional heterogeneity. As result, all of the ceramics showed diffuse phase transition and ferroelectric switching responses, with parameters affected mostly by density ( between 3.

Role of Density and Grain Size on the Electrocaloric Effect in BaCaTiO Ceramics.

Pure perovskite Ba0.90Ca0.10TiO3 ceramics, with a relative density of between 79 and 98% and grain sizes larger than 1 µm, were prepared by solid-state reaction.

Scale-Dependent Dielectric Properties in BaZrTiO Ceramics.

In the present work, BaZrTiO ceramics with grain sizes between 0.45 and 135 µm were prepared by solid-state reaction and classical sintering. The effect of grain size on dielectric properties was systematically explored, and it was found that dielectric permittivity reaches a maximum value for grain sizes between 1.

Effect of Porosity on Functional Properties of Lead-Free Piezoelectric BaZrTiO Porous Ceramics.

The present paper reports the dependence of dielectric, ferroelectric and piezoelectric properties on the porosity level in BaZrTiO ceramics with porosity from 5% to 21%. Microporosity with 0-3 connectivity has been produced using PMMA microspheres as a sacrificial template. The functional properties (dielectric, ferroelectric and piezoelectric effect) are mostly affected by the "dilution effect": permittivity decreases by 40% when porosity increases by 21%, and P decreases from 13 to 5 µC/cm while the P is in the range of (2-8) µC/cm.