Effect of sintering temperature on varistor and dielectric properties of Si–polymer composite films

Silicon–polyaniline–polyethylene composite films were prepared through hot pressing at a pressure of 60 MPa and different temperatures and their current–voltage characteristics were investigated. Results show that these films have varistor behavior and can be used to protect circuits from 64 V up to 80 V overvoltages. In addition, it is found that the varistor breakdown voltage decreases by increasing sintering temperature while the corresponding nonlinear coefficient increases. Dielectric properties of the films vary as a function of frequency in such a way that, at low frequencies, capacitance, relative permittivity and loss coefficient of the samples, as well as their fluctuations, are high. By increasing frequency, both dielectric properties of the films and their reduction rate decrease. On the other hand, by increasing sintering temperature, capacitance and relative permittivity of the varistors tend to increase at a constant frequency whereas their loss coefficient decreases.