Effect of particles size on the AC electrical behavior of iron/polystyrene composites

The AC electrical characteristics of polystyrene/Iron composites filled with iron particles of average sizes: 5, 40, 110 and 250 mu m, have been investigated. The AC electrical properties were studied in frequency range (50 kHz-1 MHz), and temperature range (30-110 A degrees C) using the impedance method. The AC-conductivity and dielectric constants were determined from the measured impedance data. It was found that the applied frequency, temperature, and iron particles size affect the electrical and dielectric properties of the composites. The AC-electrical conductivity is increasing with temperature. The dielectric constant and the dielectric loss of the composites increase with decreasing the iron particles size. The universal power-law of the electrical conductivity gives exponent with 0 < m < 1 characterizing hopping conduction. The small values of the activation energy indicate that the composite of smallest iron particle size, electrons can tunnel or hop more easily from the valence band to conduction energy band due to the reduction of interparticles separation.