Na1/3Ca1/3Bi1/3Cu3Ti4O12/poly(vinylidene fluoride) composites with high dielectric permittivity and low dielectric loss

Polymer matrix composites of Na1/3Ca1/3Bi1/3Cu3Ti4O12/PVDF with various volume fractions of filler were fabricated. Na1/3Ca1/3Bi1/3Cu3Ti4O12 powders synthesized using a conventional mixed-oxide method were used to incorporate in a PVDF polymer for increasing the dielectric permittivity (epsilon'). The phase formation and morphologies of the composites were characterized. Na1/3Ca1/3Bi1/3Cu3Ti4O12 particles were found randomly distributed and quite good dispersed in the PVDF polymer. The polar beta- and gamma-PVDF phases as well as the nonpolar alpha-PVDF phase were confirmed to exist in the polymer composites. Interestingly, a low loss tangent (tan delta similar to 0.075) and greatly enhanced epsilon' similar to 156 with low temperature coefficient (Delta epsilon' similar to 8.65%) at 150 degrees C were obtained in Na1/3Ca1/3Bi1/3Cu3Ti4O12/PVDF composites with 50 vol% filler. Theoretical prediction of the effective epsilon' of composites was performed to clarify the origins of the improved dielectric properties. Accordingly, the largely enhanced epsilon(') resulted from the high-permittivity of Na1/3Ca1/3Bi1/3Cu3Ti4O12 particles used and from interfacial polarization in the composites, while the low value of tand was due to the initially low tand values of filler ceramics particles.