Ionic conductivity studies on neodymium doped ceria in different atmospheres
TL;DR: In this article, nano-crystalline 10 and 20 mol% neodymium (Nd) doped ceria powders were prepared by gel-combustion synthesis.
Abstract: Nano-crystalline 10 and 20 mol% neodymium (Nd) doped ceria powders were prepared by gel-combustion synthesis. The single-phase nature of the nano powder has been confirmed by X-ray diffraction. These sinter-active nano powders resulted in dense products, as the sintered densities were found to be ∼90% of theoretical densities. Ionic conductivity studies were carried out in air, hydrogen and oxygen atmospheres. The samples showed ionic conductivity of 1.3 × 10−2 S cm−1 at 650°C, and the activation energy values obtained in this system were in the range of 0.7-1.0 eV. These studies also revealed that no electronic conduction was observed, as the ionic conductivity values were almost similar in different environments.
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TL;DR: In this paper, a gel combustion method using urea-formaldehyde as fuel for Nd doping was used to synthesize nanocrystalline neodymium-doped ceria solid solutions with Nd3+ concentrations varying from 4 to 20 mol pct.
Abstract: Nanocrystalline neodymium-doped ceria solid solutions with Nd3+ concentrations varying from 4 to 20 mol pct have been synthesized by gel combustion method, using urea-formaldehyde as fuel for Nd doping. The combustion reaction is explained through differential scanning calorimetry (DSC)-differential thermogravimetric analysis (TGA), whereas the synthesized materials are characterized through X-ray diffractometry (XRD), field-emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). The phase obtained from the exothermic reaction contains Nd-substituted CeO2. The deviation of the lattice parameter from Vegard’s law and the decrease in crystallite size with dopant concentration has been explained. The as-synthesized particles are largely nanoporous single crystallites, existing in loosely held spherical-shaped agglomerates. The size of the agglomerates increases with increasing dopant content. High-resolution TEM (HRTEM) reveals the fact that the unit cells are strained.
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