Conduction and relaxation mechanisms in gadolinium oxide nanoparticle doped polyvinyl alcohol films

Abstract Concentration dependent dielectric and electrical properties of PVA-Gd2O3 nanocomposite films over a wide range of frequencies (100Hz-1 MHz) and temperatures (303 K–423 K) is reported here. TEM of the Gd2O3 nanoparticles showed that they could be indexed to the cubic phase. The frequency variation of the dielectric permittivity and dielectric loss could be explained by the Maxwell Wagner Sillar’s model. The dielectric permittivity decreased in the composite films contrary to observations in other similar systems. The complex impedance showed Arrhenius behavior and the activation energies decreased monotonically with increasing concentration. However the resistivity of the nanocomposite films shows an increase with concentration, the 4 wt% film showing the highest resistivity which indicates other contributions to conductivity. The Nyquist plot could be fitted to a simple parallel RC circuit showing the presence of long range conduction in these samples. The relaxation times varied from 10−4 to 10−6s and indicated a non-Debye type of relaxation. The master curve showed good overlap indicating that the same relaxation processes were active at all temperatures. The ac conductivity obeys Jonscher’s law and the exponent shows a monotonic decrease with temperature. This indicates that Correlated Barrier Hopping is the probable mechanism for conduction in these samples.