Conductivity of Beta‐Alumina Highly Doped with Iron

Complex plane impedance diagrams were used to determine the ionic conductivity of Fe‐doped β‐alumina over the composition range (10% Fe by weight) to (30% Fe by weight). The influence of starting material [ , , , ] upon grain boundary and bulk properties was studied. The ionic conductivity of all doped materials increased over that of undoped β‐alumina. The best materials obtained resulted from doping with . At the 10% doping level, bulk conductivity reached a maximum coinciding with a minimum in activation energy. Electronic conductivity was investigated by a "floating" blocking technique. The electronic conductivity was small at the 15% dopant level, representing <10 −3 % of the total conductivity, but increased rapidly and at the 30% dopant level was ∼0.1% of the total conductivity. Preliminary Mössbauer studies showed a steady increase in the Fe(III)/ Fe(II) ratio as dopant levels increased.