Superior dielectric properties in Na0.35%Ba99.65%Ti99.65%Nb0.35%O3/PVDF composites

In this paper, the recently developed environmentally friendly lead-free ferroelectric Na0.35%Ba99.65%Ti99.65%Nb0.35%O3 (NNBT) was firstly used as filler to synthesize ceramic-polymer composites using polyvinylidene fluoride (PVDF) as martix. The composites PVDF-xNNBT with different volume fractions of x = 0, 0.1, 0.2, 0.3, 0.4, and 0.5, were prepared via solution mixing and hot pressing method. Dielectric properties were investigated in the temperature range from room temperature to 250 °C and frequency range of 102-106 Hz. All the investigated composites show high dielectric constant (>100) and low loss tangent (<5%). The best dielectric properties were found in PVDF-0.5NNBT, which shows weakly frequency and temperature dependent dielectric constant of 220 and low loss tangent of 0.037 at 1 kHz. Interfacial relaxation arising from the ceramic-polymer interfaces was suggested to be the main reason of the superior dielectric properties.