Greatly enhanced dielectric permittivity in La1.7Sr0.3NiO4/poly(vinylidene fluoride) nanocomposites that retained a low loss tangent

Abstract

The effect of La1.7Sr0.3NiO4 nanoparticles (LSNO-NPs) on the dielectric properties of LSNO-NPs/polyvinylidene fluoride (LSNO-NPs/PVDF) composites is presented. LSNO-NPs/PVDF composites fabricated via a liquid-phase assisted dispersion and hot-pressing methods showed a homogeneous dispersion of LSNO-NPs in a PVDF polymer matrix. The dielectric permittivity (epsilon') continuously increased with increasing volume fraction of LSNO-NPs from f(LSNO) = 0-0.20, following the effective medium theory and Lichtenecker's logarithmic models. This result was intrinsically caused by a very large epsilon' approximate to 10(5) of LSNO-NPs ceramic particles. At f(LSNO) = 0.25, 30 epsilon' deviated from the conventional mixed models, indicating a dominant extrinsic effect. A rapid change in epsilon' of LSNO-NPs/PVDF composites was observed when f(LSNO) > 0.3. A largely enhanced dielectric response with epsilon' z 3285 at 1 kHz was obtained at f(LSNO) > 0.35, while the loss tangent was still low (approximate to 0.83). This extremely enhanced epsilon' value is attributed to the large interfacial areas and very short interparticle distances between LSNO-NPs (z20-30 nm) separated by a thin layer of PVDF, forming highly effective microcapacitors. The overall 30 values are well described by the combination model of effective medium percolation theory.