Anomalous behavior of the dielectric and electrical properties of polymeric nanodielectric poly(vinyl alcohol)-titanium dioxide films

The complex dielectric permittivity, alternating-current electrical conductivity, electric modulus, and impedance spectra of polymeric nanocomposite (PNC) films consisting of a poly(vinyl alcohol) (PVA) matrix dispersed with nanosize particles of titanium dioxide (TiO2); (i.e., PVA-x wt % TiO2, where x is 0, 1, 3, or 5) were investigated in the frequency range 20 Hz to 1 MHz at ambient temperature. A detailed analysis of the results showed that the values of the dielectric and electrical parameters of these PNC-based nanodielectric films varied anomalously with increasing TiO2 concentration. The temperature-dependent dielectric characterization of the PVA-3 wt % TiO2 film revealed that the dielectric polarization at a fixed frequency increased nonlinearly with increasing temperature. The temperature-dependent electric modulus relaxation time values of the nanodielectric film obeyed Arrhenius behavior. The X-ray diffraction study confirmed that the crystalline phase of the PVA matrix decreased with increasing TiO2 concentration; this suggested that the interaction of the TiO2 nanoparticles caused some destruction of the hydroxyl group dipolar ordering in the hydrogen-bonded crystalline structure of the pristine PVA matrix. The intensities of the diffraction peaks of the TiO2 nanofiller were enhanced as its concentration increased in these nanodielectrics; this confirmed the existence of TiO2 nanoparticles inside the crystalline phases of the PVA matrix. The surface morphology of the films was examined by the study of their scanning electron micrographs. The feasibility of using these flexible polymeric nanodielectric films as electrical insulators and dielectric substrates in low-power microelectronic devices operated at audio-and radio-frequency electric fields was explored. (C) 2016 Wiley Periodicals, Inc.