||Determination of absolute charge
carrier densities in catalysts under reaction conditions
The goal of this project is the development
of a technique for the quantitative determination of charge carrier
densities and Hall mobilities in powder catalysts under reaction
conditions. In general, the electrical conductivity s is given by
the product of the elementary charge e, the charge carrier density
N and the Hall mobility µ : σ = e N µ.
As a consequence, the absolute charge carrier density can be deduced
by measuring the Hall mobility and conductivity. Since 4-contact
Hall effect measurements of powders are very difficult due to erroneous
contact resistances, Hall mobilities are to be measured with the
contactless microwave cavity perturbation technique. For this purpose,
we are developing bimodal microwave resonators that enable the investigation
of microwave Hall mobilities of powders in a static magnetic field.
The measurements are to be performed in a quartz reactor connected
to a gas delivery manifold and gas analytics in order to study simultaneously
the catalytic performance of the investigated catalyst.