Dependence of dielectric properties on BT particle size in EP/BT composites

The polymer-ceramic composites of epoxy resin (EP) and barium titanate (BT) were prepared. BT powders of different BT particle sizes from 100 nm to 1 mu m were used in the preparation. The dielectric properties, such as dielectric constant, dielectric loss and electrical breakdown strength, of the EP/BT composites were studied. The morphology of the composites was characterized by the means of scanning electron microscopy (SEM). The results show that the dielectric constant of the composites is much higher than the epoxy matrix at frequency range from 1 kHz to 10 MHz, and it is also obviously dependent on the size of BT particles. The electrical breakdown strength of the composites decreases with the increase of the BT content. The dependence of electrical breakdown strength on BT particle sizes was also discussed.