Wagner method

The extension of this Kobayashi—Wagner method to studies of heterogeneous catalysis is straightforward as suggested [54], since catalytic redox reactions can be regarded as repetitive cycles of reduction and oxidation of the surface species [64]. Examples are the studies of H2 + S2 - H2S and COS + H2 - > CO + H2S on Ag2S [57], and of CO + H20 C02 + H2 on Fe 0 [58]. This method, however, is based on the... 

Similar approaches are used for most steady-state measurement techniques developed for mixed ionic-electronic conductors (see -> conductors and -> conducting solids). These include the measurements of concentration-cell - electromotive force, experiments with ion- or electron-blocking electrodes, determination of - electrolytic permeability, and various combined techniques [ii-vii]. In all cases, the results may be affected by electrode polarization this influence should be avoided optimizing experimental procedures and/or taken into account via appropriate modeling. See also -> Wagner equation, -> Hebb-Wagner method, and -> ambipolar conductivity. 

Approaches for the description of interfacial processes involving various solid materials, particularly - ion conductors, and the theoretical background for the determination of minor contributions to the total conductivity of solids. These achievements made it possible to develop the measurement methods, which today have principal importance for the field of solid-state electrochemistry (see also -> diffusion determination in solids and - Hebb-Wagner method). 

Based on the Wagner method [16], the required character of conductivity can be achieved by the introduction of admixture into the basis oxide, which has a common anion with the basis oxide, and the cation has less valence. Type and quantity of the defects are stipulated by the admixture and its concentration. As a rule, the majority of well-known solid electrolytes with pure oxygen-ionic conductivity have a fluorite CaFj crystalUne structure [17]. 

The partial ionic or electronic currents and conductivities can also be measured by setting the driving force for the other partial current to zero. If one examines the Hebb-Wagner method, it becomes apparent that this nullification also occurs there. Because of the extreme resistance of the ion-blocking electrode to ionic current, the driving force for ionic motion in the MI EC vanishes (V/iion = 0). 

Quicker than Wagner method but otherwise the same problems. 

Jaworsky, followed by many other researchers in and outside Reformatsky s research group, applied the one-step Saytzeff-Wagner method in which zinc was replaced by magnesium ... 

The Analog of the Hebb-Wagner Method for Determining Oj Selective Probes... 

FIGURE 8.3. Cell arrangement for the measurement of the partial electronie conductivity according to the Hebb-Wagner method. Specifie example the MIEC conducts 0 ions and electrons/holes. The polarity of the... 

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