DENSIFICATION OF YTTRIA-STABILIZED ZIRCONIA - IMPEDANCE SPECTROSCOPY ANALYSIS

Yttria-stabilized-zirconia samples with fairly narrow pore size distri butions give well-defined microstructure impedance semicircles which c an be characterized by a blocking factor alpha(R), a capacitance ratio alpha(C), and a frequency ratio alpha(F). On an alpha(R) vs. alpha(C) diagram, the regimes where either the pores or the grain boundaries a re dominant are clearly separated. As expected from the reference mode l, the alpha(R) alpha(F) product was found proportional to porosity. T he fairly continuous variations of alpha(F) from the densification to the grain growth regime revealed that voids remained present along the grain boundaries. Comparison of different results shows a remarkable constancy of the average thickness of the grain-boundary blockers in t he samples sintered at high temperature. The electrical bulk propertie s obey simple laws as functions of porosity, which allows us to correc t the conductivity and dielectric-constant data obtained with imperfec tly densified materials.