Synthesis of Polythiophene-BaTiO3 Nanocomposite in aqueous media and Electrophoretic Deposition of Composite Thin Film for Dielectric Applications

Abstract

Processibility and dielectric properties of Barium Titanate (BaTiO3), which is an excellent dielectric material, were enhanced by preparing its composite with conducting polythiophene(PTh) polymer. Composite, possessing polythiophene encapsulated Barium Titanate nanoparticles was prepared via heterogeneous oxidative polymerization of thiophene by copper (II) Sulphate in presence of BaTiO3 nanoparticles with average size of 60nm. The purpose of using BaTiO3 nanoparticles of 60nm size was to increase BaTiO3-Pth interphase and reduce number of voids and pores to get uniform dielectric behavior. The morphology of the Composite was studied by SEM, proving the presence of Core-shell structures. FTIR and XRD confirmed the formation of composite. Dielectric loss and dielectric constant of pressed pellets of composites with different BaTiO3-PTh ratios were measured by LCR meter. Coating of polythiophene on BaTiO3 nanoparticles decreased the dielectric loss from 0.04 for pure BaTiO3 up to 0.008 with 40% PTh at 1.2 MHz. Maximum Dielectric constant of 30 at low frequency for 20%polythiophene and 80% BaTiO3 was observed. Moreover, the resultant composite shows quite stability in dielectric properties in the range of 10 GHz to 15GHz. Electrophoretic deposition technique was employed to form thin films of polythiophene coated BaTiO3 nanoparticles on conducting substrates (ITO, Cu, Stainless steel). Uniform films with average roughness of 9 nm by AFM and thickness of 360 nm by SEM and AFM were observed. Chemical nature of films was confirmed by FTIR and EDS