EFFECT OF INTERGRANULAR GLASS-FILMS ON THE ELECTRICAL-CONDUCTIVITY OF 3Y-TZP

The electrical conductivity of 3Y-TZP ceramics containing SiO2 and Al2O3 has been investigated by complex impedance spectroscopy between 500 and 1270 K. At low temperatures, the total electrical conductivity is suppressed by the grain boundary glass films. The equilibrium thickness of intergranular films is 1-2 nm, as derived using the ''brick-layer'' model and measured by HRTEM. A change in the slope of the conductivity Arrhenius plots occurs at the characteristic temperature T(b) at which the macroscopic grain boundary resistivity has the same value as the resistivity of the grains. The temperature dependence of the conductivity is discussed in terms of a series combination of RC elements.