Wagner-Hebb

Figure 42. Steady-state results of a Wagner-Hebb polarization of Y-doped Z1O2 or TI1O2 with the aid of the cell 0N2, Pt YSZ or YST air, Pt (left, current-voltage curve for Tho.9Yo.1Ch 95 (YST), right partial conductivities for Zro.9Yo.1O1.95 (YSZ)).232 Reprinted from L.D. Burke, H. Rickert, and R. Steiner, Z Phys. Chem. N.F., 74 (1971) 146-167. Copyright 1971 with permission from Oldenbourg Verlagsgruppe.

Figure 42 depicts steady-state results of a Wagner-Hebb polarization of (Y203-doped) Zr02 and Th02 for which the ideal Wagner-Hebb relation is valid.232... 

The analogous conclusions are arrived at for the ionic conductivity in the case of cell 5. The blocking technique can be extended in order to de-convolute ionic and electronic conductivities for a grain boundary of a bicrystal (see Figure 43)236 or even in composites.240 In both the cases, the relations are substantially more complicated because of local inhomogeneities. Some of the pitfalls of the Wagner-Hebb technique have been described by Riess.241... 

The steady-state result (Eq. (77)) can be directly used to separate ionic and electronic conductivities the disadvantage of the technique is that it presupposes gas-separation. If not special measures are taken, it becomes unreliable for the ionic transport number less than 1%. Thus, this method well complements the Wagner-Hebb method which is very sensitive to small transference numbers. The partial conductivities of PbO shown in Figure 48 have been de-convoluted by the emf technique just described.3... 

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