Regensburg 2007 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 31: Nano structured materials III

MM 31.1: Vortrag

Donnerstag, 29. März 2007, 11:45–12:00, H4

Influence of Grain Size and Porosity on Electrical Conductivity of Nanocrystalline Cerium Dioxide — •Adrian Ferdinand — AG Birringer, Universität des Saarlandes

The influence of grain size and porosity on the transport properties of nanocrystalline, porous cerium dioxide was investigated by impedance spectroscopy. Magnitude and type (ionic vs. electronic) of electrical conductivity of cerium dioxide depends on parameters such as acceptor concentration, oxygen partial pressure of the surrounding gas phase and the grain size in the case of polycrystalline materials. Materials characterised by grain sizes in the nanometer regime and high porosity over the whole sample are interesting for further studies due to their high ratio of surface to overall interface area. Therefore, as a first approach, the influence of grain size and porosity on electrical conductivity was explored. A series of samples was prepared by consolidation and sintering of cerium dioxide nanoparticles with a sufficient variation in the two essential fabrication parameters, i.e. pressure and sintering temperature. Grain size was determined by X-ray diffraction and microscopy methods (REM), porosity by a density measurement based on Archimedes' principle. Furthermore, information on the samples' free surface area could be obtained by nitrogen adsorption measurement. Impedance spectroscopy was used to measure the electrical conductivity. The experimental results are discussed in terms of the space charge model for polycrystalline ionic material.