Study of dielectric constants of binary composites at microwave frequency by mixture laws derived from three basic particle shapes

Powder mixture rules derived from the filler particles with the shapes of sphere, cylinder or rod, and lamella or disk with random distributions are studied in this paper. Three ceramic powders of fillers with dielectric constants of 10, 20, and 36, respectively, are adopted. The experimentaldielectric constantsof ceramicdispersions in thepolyethylenematrix atmicrowave frequency are compared to those obtained by using different mixing laws. The mixing rules are also adopted to estimate the dielectric constants of pure ceramics from the measureddielectric constants of compositeswithvarious concentrations. The theory for the error of estimation is studied. In contrast to the traditional concept of obtaining the best curve fitting ofmixture rulewith theexperimental data, this studyconclude avery important concept on the powdermixture rule, that is, themost adequatemixture law for estimating the dielectric constants of pure ceramics requires both good curve fitting and potential of less error. 2008 Elsevier Ltd. All rights reserved.