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The total and partial electronic conductivities of gadolinium doped ceria (Ce 0.95 Gd 0.1 O 1.95− δ : GDC) with nanometer grain size have been evaluated in an attempt to identify the nanosize effect in heavily doped ceria. Nanocrystalline GDC bulk specimens with relatively high densities (≥96% of theoretical density) and various grain sizes (70, 100, 170 nm) were successfully fabricated by a conventional solid-state sintering method. According to the measurements of total and partial electronic conductivity via AC-impedance and DC polarization methods, respectively, no significant grain size dependence appeared for either type of conductivity. Furthermore, both total and partial electronic conductivity were not significantly different from those of microcrystalline GDC, which indicated that, upon nanostructuring within the examined grain size range, nanostructured bulk GDC was not affected by any nanosize effect: either space charge layer effect or grain boundary blocking effect. |
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