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In order to further improve the performance of 0.94[(Bi0.5Na0.5)TiO3]‐0.06BaTiO3/polyvinylidene fluoride (NBT‐BT/PVDF) flexible composite films prepared by the hot‐pressing method, the effect of surface modification of the NBT‐BT particles on the structure and properties of the films was investigated. Two coupling agents, namely, (3‐aminopropyl)triethoxysilane (APTES) and dodecyl triethoxysilane (DDTES) were added to enhance dispersion and interfacial adhesion of the active phase powder with the polymer matrix. The highest amount of the electroactive PVDF β‐phase was formed in APTES‐modified samples while in DDTES samples mainly γ‐phase was formed as shown by Fourier‐transform infrared spectroscopy analysis. Differential scanning calorimetry measurements indicated that the addition of filler particles reduced the total crystallinity degree of the PVDF. Dielectric permittivity values as well as dielectric losses decreased for silanized samples due to reduced tension at the interface between particles and polymer. Strong intermolecular interaction between the PVDF chains and the APTES‐modified particles led to enhanced breakdown strength of these samples. The highest level of agglomeration in the DDTES‐modified samples induced the deterioration of ferroelectric properties. The highest voltage output of ~15 V and 225 μW of power was obtained for the APTES‐modified harvester, evidencing their potential for energy harvesting applications. Highlights: Surface of NBT‐BT particles was successfully modified by the silanization method.NBT‐BT‐PVDF flexible lead‐free composite films were prepared by hot pressing.APTES coupling agent enabled the transformation of PVDF α‐phase into electro‐active β.APTES‐modified samples showed the highest breakdown strength.Notable properties for energy harvesting application found, up to 225 μW of generated power. [ABSTRACT FROM AUTHOR]

Multiferroic composites with general formula Ba(Ti0.95Zr0.05)O3 – Ni0.7Zn0.3Fe2O4, Ba(Ti0.95Zr0.05)O3 – CoFe2O4, Ba(Ti0.95Zr0.05)O3 – Ni0.7Cu0.01Sm0.05Zn0.29Fe1.95O4, (BTZr(95–5) – NZF, BTZr(95–5) – CF, BTZr(95–5) – NCuSmZF) were prepared by mixing chemically obtained different types of ferrites and BTZ(95–5) powders in the planetary mill for 24 h. The optimization of sintering process was performed and powders were pressed and sintered at 1300 °C for obtained composites samples. From the X-ray analysis for single phase and composites ceramics the formation of crystallized structure of ferrites and barium zirconium titanate can be noticed. SEM analyses indicated the formation of two types nanosized grains, polygonal ferromagnetic and rounded ferroelectric grains. The electrical properties of these materials were investigated using impedance spectroscopy and analysis of ferroelectric measurements. Impedance analysis of all investigated samples has shown different relaxation processes that originated from the grain and grain boundary contributions. The results of polarization vs. electric field measurements have shown the influence of magnetic phase type and its concentration on the ferroelectric properties of the composites. Due to high conductivity of ferrite phases and presence of interfacial polarization, the shapes of these curves differed from the conventional ferroelectric materials. [ABSTRACT FROM AUTHOR]