Impedance spectroscopic estimation of inter-granular phase distribution in 15 mol% calcia-stabilized zirconia/alumina composites

The distribution of inter-granular glass phase in 15 mol% calcia-stabilized zirconia containing 0.3 or 10 μm size Al2O3 was estimated using a series of complex impedance spectra attained by successive removal of outer layers and subsequent measurements. For the instance of fine Al2O3 addition, the grain boundary at the near-surface region became more resistive than that at the center when sintered at T⩾1550°C, which emanated from the outward expelling of inter-granular phase during grain growth. In comparison, the coarse Al2O3 addition showed the homogeneous distribution of grain-boundary resistivity (ρgb). The ρgb as a function of sample depth could be an effective and sensitive index for determining the distribution of inter-granular phase.