Characteristics impedance spectroscopy: Tool to characterize ion-blocking phenomena

Scandia (Sc₂O₃) doped nano-crystalline zirconia powder was prepared by dissolution and co-precipitation method. Bulk specimens were prepared by sintering nano-powders at various temperatures. The characteristics admittance diagrams obtained from impedance spectroscopic measurement revealed the grain interior, defect (blocker) and grain boundary conductance. The ion-blocking model stressed the role played by the distribution of the current lines around the blockers and by the dielectric properties of these blockers. With temperature, no variation of the blocking factor was observed. This model is consistent as per similarity between the bulk and blocked conductance activation energies are concerned. The admittance diagram parameters were correlated to the geometrical parameters of the blockers.