Impedance spectroscopic behaviour of spark plasma sintered nanocrystalline scandia stabilized zirconia (SSZ)

Nanocrystalline scandia (Sc₂O₃) doped zirconia was prepared by dissolution and co-precipitation method. The formation of the nanostructured nearly cubic phase has been observed from transmission electron microscope and X-ray diffraction studies. Spark plasma sintering retains the nano/submicrograin structure. The frequency dependent conductivities were measured in the frequency range from 100 Hz to 1 MHz and at temperatures 300–800 K. The impedance diagram shows the grain interior and grain boundary resistance contributions. The frequency dependent conductance spectra show the DC plateau (at low frequency region) and dispersive region suggesting the correlated hopping motion of ions. The dielectric-loss spectra suggest the presence dielectric relaxation, which is related to enthalpy of ion hopping. Characteristic hopping frequencies were calculated and appear to be related to the thermally activated ion hoping process.