Electrical properties of poly aniline nickel nanocomposites prepared by ball milling method

Search for efficient thermoelectric materials for waste heat management, power generation and other purposes has been gaining interest in recent times. Conventional thermoelectric materials are fragile in nature and cannot be shaped easily. We have chosen PolyAniline (PANI) as our base material because it is a well known conducting polymer and one can prepare flexible films out of it. To have an efficient thermoelectric material, its thermoelectric figure of merit should be high which is given by the expression: ZT = S²σT/κ Where, S is the Seebeck coefficient, σ is the conductivity, T and κ represents the absolute temperature and thermal conductivity, respectively. It is fact that to have high value of ZT we need to enhance electrical conductivity and decrease the thermal conductivity. Incorporation of metal nanoparticles into polymer matrix may increase its electrical conductivity and reduce the thermal conductivity by means of phonon scatterings. Nickel is our preferred metal for synthesis nanocomposites because it is cost effective and more stable within polymer matrix. Here, we have synthesized nanocomposite of HCl doped PANI and Ni with different weight percentages (5%, 10%) by planetary ball milling technique. The nanoparticles have been characterized by XRD, UV-Vis and FTIR Spectra. Frequency dependent dielectric measurements have been carried out at room temperature. The real part of impedance decreases with increase in frequency which may be due to combined effect of dipolar, electronic and orientation polarization. The frequency dependent AC conductivity curve reveals enhancement in conductivity by the order of almost 10⁵ of magnitude by incorporating Ni nanoparticles. At higher frequency, conductivity becomes more disperse due to the increment of unsuccessful hoping. (author)