Atypical dielectric behavior in sol–gel derived fine grain PZT/CeO2 nanocomposites

We present here dielectric and electrical modulus studies of sol–gel derived fine grain (100−x)PZT/xCeO2 nanocomposites. Dielectric response shows superimposed local maxima(s) in high frequency regimes, which, in low frequency regions seems to be overshadowed by high conductivity. Observed local maxima(s) were found to be in concurrence with the nadir(s) observed in the imaginary part of electrical modulus plotted on the temperature plane. In addition to this, calculated bulk and grain boundary capacitance exhibit maxima(s) in the measured temperature range displaying the existence of both bulk and grain boundary transition in nanocomposite formation. Therefore, a collective effect of these two processes has been thought to be a plausible mechanism for observed dielectric behavior of nanocomposites. Anomalous increase in bulk transition temperature of 2 wt% ceria substituted nanocomposite was also observed. Possibilities of increase in transition temperature have also been discussed taking in to account the extrinsic size effect.

► Ceria helped in achieving fine grain microstructure in PZT–CeO2 nanocomposites. ► Dielectric vs. temperature profile shows local maxima(s) in high frequency regime. ► Existence of both bulk and grain boundary transition in fine grain nanocomposites. ► Tetragonality does not correlate with anomalous increase in transition temperature.