title: Dependence of dielectric properties on the crystallinity of ceramic/polymer composites.
abstract: Effects of ZnNb(2)O(6) content and crystallinity of polymers on the dielectric properties of ZnNb(2)O(6)/polytetrafluoroethylene (PTFE), polypropylene (PP), and polystyrene (PS) composites were investigated at microwave frequencies. With increasing ZnNb(2)O(6) content, the dielectric constant (K) of the composites increased, whereas the dielectric loss (tanδ) and temperature coefficient of resonant frequency (TCF) decreased. The tanδ of the composites with amorphous PS was lower than those of the composites with semi-crystalline PP and PTFE. For the composites with semi-crystalline PTFE and PP, the tanδ was strongly dependent on the degree of crystallinity of composites. Several types of theoretical models were applied to predict the effective dielectric properties of the composites. Typically, K of 5.73, tan δ of 1.45 x 10(-3), and TCF of 2.66 ppm/°C were obtained for the PP composites with 0.5 volume fraction V(f) of ZnNb(2)O(6).
authors.affiliation: Department of Materials Engineering, Kyonggi University, Suwon, Korea. eskim@kyonggi.ac.kr
authors.forename: Eung Soo
authors.initials: ES
authors.lastname: Kim
authors.forename: Chang Jun
authors.initials: CJ
authors.lastname: Jeon