Na1/3Ca1/3Bi1/3Cu3Ti4O12–Ni@NiO/poly(vinylidene fluoride): Three–phase polymer composites with high dielectric permittivity and low loss tangent

Abstract

High permittivity and low loss tangent polymer matrix composites containing a low loading of filler are desirable for practical applications in modern electronic devices. In this work, greatly improved dielectric properties of poly(vinylidene fluoride) (PVDF) were accomplished by incorporating high–permittivity Na1/3Ca1/3Bi1/3Cu3Ti4O12 (NCBCTO) ceramic particles with sizes of ~0.5–1.5 μm coupled with ~1.0–2.0 μm diameter core–shell Ni@NiO particles. Phase composition, crystal structures, morphology, microstructure, and dielectric properties of NCBCTO–Ni Ni@NiO/PVDF composites were investigated. A nonpolar α–phase and polar β– and γ–phases were detected in the PVDF matrix and NCBCTO–Ni/PVDF composites. Random dispersions of small clusters of NCBCTO and Ni particles were observed in the PVDF polymer matrix. Significantly enhanced dielectric permittivity, ≈279, which was higher than that of pure PVDF polymer by a factor of ≈27, was achieved. Surprisingly, the dielectric loss tangent was suppressed to a very low value of ≈0.07 at 1 kHz. The dielectric properties of the NCBCTO-Ni@NiO/PVDF composites are discussed based on the interfacial polarization at the internal interfaces.