Complex dielectric behavior of doped polyaniline conducting polymer at microwave frequencies using time domain reflectometry

Nano size Tin Oxide is prepared in the laboratory from SnCl4 and ammonia solution. The polyaniline (PAni) conducting polymer is synthesized by chemical oxidation method using ammonium persulphate as oxidizing agent. The PAni-SnO2 composite was prepared by insitu method. Scanning electron microscopy (SEM) results confirm the particle size of SnO2 in the range of 30-48 nm. Dielectric behavior of nanocomposite of PAni-SnO2 was studied in the frequency range 0.01- 20 GHz at -5,0,5,10,15,20 and 25oC. The dielectric constant (real part ε׳) and dielectric loss (imaginary part ε״) have been evaluated. The relaxation time (τ, τo, and τ1) are calculated. The relaxation time was found to be of the order of ps. The dielectric properties of the solids in the form of powders may be useful in understanding the structural behavior of particles in an alternating field. These studies may also be used to formulate models for predicting the dielectric properties. The microwave absorbing property is decided from the dielectric loss of the material. It is observed that the PAni-SnO2 composite can be a good electromagnetic shielding material.