Coarse 8YSZ powders destined for plasma spray deposition were obtained from
three different suppliers (Hochrhein, Magnesium Elektron, Unitec). Their i
onic conductivities were measured by impedance spectroscopy on pellets prep
ared by vacuum hot pressing. Density was adequate for one powder (Unitec, 9
5%) but poor for the other two (73-80%). For the latter samples, conductivi
ty was a factor of 1.5 below reference values for pure dense 8YSZ, owing to
their porosity. For the former samples, however, the conductivity was a fa
ctor > 3 below 8YSZ reference values. An additional resistance, responsible
for this large discrepancy, appeared in the impedance response and is ascr
ibed to the distinct microstructure at intergranular zones within these oth
erwise dense samples. (C) 2001 Published by Elsevier Science Ltd. All right
s reserved.