High dielectric permittivity in semiconducting Pr0.6Ca0.4MnO3 filled polyvinylidene fluoride nanocomposites with low percolation threshold

Semiconducting Pr0.6Ca0.4MnO3 nanoparticles with width of ∼50nm and length ∼80–150nm were prepared by sol-gel method. The dielectric behavior of Pr0.6Ca0.4MnO3, polyvinylidene fluoride composites was investigated by varying the Pr0.6Ca0.4MnO3 volume fraction and frequency. The percolation threshold of the composites was found to be 0.1 and an enhanced effective dielectric permittivity of ∼700 with low dielectric loss of ∼0.3 at 103Hz near the percolation threshold was observed. The low percolation threshold was attributed to the nanosize and nonspherical shape of the filler particles, and the enhanced dielectric properties have been explained by using boundary layer capacitance effect and percolation theory.