Dependence of dielectric properties on the crystallinity of ceramic/polymer composites

摘要

Effects of ZnNb2O6 content and crystallinity of polymers on the dielectric properties of ZnNb2O6/polytetrafluoroethylene (PTFE), polypropylene (PP), and polystyrene (PS) composites were investigated at microwave frequencies. With increasing ZnNb2O6 content, the dielectric constant (K) of the composites increased, whereas the dielectric loss (tan;4;) and temperature coefficient of resonant frequency (TCF) decreased. The tan;4; 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 tan;4; 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 ;4; of 1.45 x 10-3, and TCF of 2.66 ppm/u000b0;C were obtained for the PP composites with 0.5 volume fraction Vf of ZnNb2O6.