Microstructure characterization and electrical transport properties of nanocrystalline Fe and Fe-doped cubic zirconia cermets synthesized by mechanical alloying

•The dc conductivity of the samples increases with increasing temperature.•Monoclinic phase transforms to cubic phase.•The activation energy decreases as Iron content increases in the sample.•Undoped sample shows a maximum in the temperature behavior of ‘s’.•Interfacial boundary resistances are larger than grain resistances.

Here we report the dielectric permittivity and transport mechanism of nanocrystalline metallic Fe–ZrO2 solid solution synthesized by high energy ball-milling method in the temperature range 298–523 K and in the frequency range 20 Hz–1 MHz. Formation mechanism, structural and microstructural changes of different phases and relative phase abundances have been estimated by Rietveld analysis of XRD patterns. The direct current conductivity study shows decrease in activation energy with increase in iron percentage. The adiabatic small polaron model is found to govern the dc transport process throughout the temperature range. Alternating current conductivity is found to follow the power law σ′(f,T) = fsTn. A transformation from small polaron hopping to correlated barrier hopping has been observed in undoped sample. The ac impedance study shows the grain boundary contribution to be predominating over the grain contribution.

Graphical abstractThe temperature variation of universal dielectric response parameter ‘s’ is found to obey the correlated barrier hoping model for doped samples, however a transformation from small polaron hopping to correlated barrier hoping model has been observed in undoped sample.Figure optionsDownload full-size imageDownload as PowerPoint slide