IMPEDANCE SPECTROSCOPY OF MG-PARTIALLY STABILIZED ZIRCONIA AND CUBIC PHASE-DECOMPOSITION

Electrical conductivity measurements were carried out by impedance spe ctroscopy on nominally pure and magnesia-doped zirconia in the 3-13.7 mol% concentration range. In the partial-stabilization field, the impe dance diagram show the characteristic grain and grain boundary semicir cles, as well as an extra are at intermediate frequencies. This extra arc is interpreted as a characteristic of partial blocking of electrol yte conduction by the monoclinic grains. As usual, the resistances ass ociated with the blocking processes exhibit activation energies slight ly higher than the bulk resistance. All these activation energies incr ease with the MgO content. The cubic phase decomposition can easily an d accurately be monitored by impedance spectroscopy.