Nanocrystalline ZrO2‐ and Y2O3‐powders with grain sizes from 5‐20 nm were prepared by the Inert Gas Condensation method. The powders were mixed in different fractions, pressed into green bodies and sintered to ceramic samples with 35‐49 nm average grain size. The phase, grain size and specific surface area of the powders and ceramic samples was characterized by X‐ray diffraction and nitrogen adsorption. Densities from 82 to 93% of the single crystal density were determined using the Archimedes principle. The complex conductivity was measured for frequencies ranging from 20 Hz to 3 MHz at temperatures between 80 and 1100 K. The lattice relaxation, grain boundary relaxation and the contact process could be resolved and identified. The dc‐conductivity for the lattice and the grain boundaries were deduced from the data. The activation energies for dc‐conductivity were determined for the lattice and the grain boundaries as 0.85 ± 0.05 and 1.0 ± 0.1 eV, respectively.
Impedance Spectroscopy, X-Ray Diffraction and High Resolution Scanning Electron Microscopy have been used to study the effect of extremely fine grain size on electrical properties such as dc-conductivity and activation energies in nanocrystalline Y-stabilized tetragonal zirconia. The samples were prepared from powders produced by the Inert Gas condensation method. X-Ray Diffraction was used to characterize phase and average grain size of the sample. In addition, grain size and microstructure of the sample was examined using High Resolution Scanning Electron Microscopy. With Impedance Spectroscopy relaxations of O−2-ions in the lattice and in the grain boundaries could be resolved. The dc-conductivities of the lattice and the grain boundaries were deduced from the data. The activation energies for ac- and dc-conductivity of the lattice and grain boundary relaxation are reported.
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