Fabrication and Dielectric Properties of Ba_0.6Sr_0.4TiO₃/Poly(vinylidene fluoride)-Poly(methyl methacrylate) Composites

Ba_0.6Sr_0.4TiO₃ (BST)/poly(vinylidene fluoride) (PVDF)-poly(methyl methacrylate) (PMMA) composite films were prepared by tape casting and hot pressing. The effects of PMMA content on the phase structure and electrical properties of the composites were studied. The results showed that the BST phase was uniformly dispersed in the polymer matrix. The interface between the two polymers is not clear, which is attributed to the good compatibility between PMMA and PVDF. With the increase of PMMA content, the dielectric constant of the composites is negatively correlated with the breakdown strength and dielectric tunability. BST/PVDF-PMMA15 composite with PMMA content (volume fraction) of 15% showed the best dielectric properties with the dielectric constant of 23.2, the dielectric loss of 0.07, the breakdown strength of 1 412 kV·cm^-1, and the dielectric tunability was 26.2% under the DC bias of 550 kV·cm^-1.