A.C. conductivity measurements of promoted nickel catalysts used for heavy water production

The a.c. conductivity of nickel catalysts promoted with Cr2 O3, Fe2 O3, Mn O and Co O was examined using a conductivity bridge and applying the complex impedance method. The obtained semicircles permitted calculation of the electrical conductance for the examined samples. The results show that they have an electronic nature. The electrical properties of catalysts depend on their structure and composition. Their resistance may be a combination of bulk crystal resistance and grain boundary one. The variation of conductivity with temperature for the examined catalytic systems shows an increase of resistance with decreasing temperature, indicating an activated conduction and semiconductor nature. 1 fig, 1 tab