Dielectric and optical properties of PVA/PAN doped TiO2 NPs

Titanium dioxide nanoparticles (TiO2 NPs) were prepared by sol–gel method. The effect of TiO2 NPs on structure, dielectric and optical properties of PVA/PAN films was reported. The X-ray diffraction (XRD) and high resolution scanning electron microscopy (HR-SEM) it were used to characterize the prepared samples. The XRD result shows the phase formation of TiO2 as anatase, with average crystal size of about 50 nm. PVA/PAN-TiO2 nanocomposite films have an amorphous nature. In addition, the dielectric constant ε′, the electric modulus M″ and the ac conductivity (σac) were studied also. It was found that ε′ increases with temperature, dielectric relaxation observed by electric modulus M″, which may be associated with Micro-Brownian motion of the main PVA/PAN chains. The ac conductivity supports hopping mechanism for the nanocomposite films. The optical investigations show that, increasing TiO2 content of the samples results in a decrease of the optical band gap accompanied with an increase of the refractive index and electric susceptibility of the nanocomposite films