Effect of interparticle distance and interfacial area on the properties of insulator –conductor composites

Abstract

The influence of conducting phase characteristics on dielectric properties of insulator-conductor composites was demonstrated by studying composites of polytetrafluoroethylene and different volume fractions ofLa0.5Sr0.5CoO3-y (LSCO). LSCO was prepared as coarse grained powder by solid state reaction and as fine powder by citrate gel method. The composites with fine powderof LSCO showed a rapid increase in dielectric constant and conductivity at 30%, while the corresponding value for coarse powder was 50%. The oeercikative behavior was found when the interparticle distance reduced to ~250 nm in both cases. The permitivity and conductivity of the composites were found to increase with the interfacial area.