Complex plane analysis of the impedance and admittance of polycrystalline sodium-β-alumina doped with transition metal ions

The bulk and grain boundary conductivities of undoped and doped β-alumina have been analyzed using complex plane techniques. Dopants included iron, chromium, cobalt, manganese and nickel. Except for chromium which is present as Cr(IV) all dopants increased the bulk conductivity. In nearly all cases an increase in sodium content was also observed in the doped samples and was a significant factor in the observed conductivity increase.The grain boundary conductivity did not show any marked change with doping although high doping levels of iron (8%) and manganese (4%) showed a large decrease in grain boundary conductivity.