TY - JOUR
T1 - Solid solubility and transport properties of Ce1-xNdxO2-δ nanocrystalline solid solutions by a sol-gel route
AU - Li, Liping
AU - Lin, Xiaomin
AU - Li, Guangshe
AU - Inomata, Hiroshi
N1 - Funding Information:
This project was financially supported by a fund of the National Natural Science Foundation of China (NSFC) (No. 19804005) (L.L.). The authors thank the Japanese Ministry of Education, Science, Sports, and Culture for meeting the publication charge of this work.
PY - 2001/11
Y1 - 2001/11
N2 - Ce1-xNdxO2-δ (x = 0.05 to 0.55) nanocrystalline solid solutions were prepared by a sol-gel route. X-ray diffraction analysis showed that Ce1-xNdxO2-δ crystallized in a cubic fluorite structure. The lattice parameter for the solid solutions increased linearly with the dopant content. The solid solubility of Nd3+ in ceria lattice was determined to be about x = 0.40 in terms of the nearly constant lattice parameters at a dopant level larger than x = 0.40. First-order Raman spectra for Ce1-xNdxO2-δ at a lower dopant content exhibited one band associated with the F2g mode. At higher dopant contents, F2g mode became broadened and asymmetric, and a new broad band appeared at the higher frequency side of the F2g mode. This new band was assigned to the oxygen vacancies. The electron paramagnetic resonance spectrum for x = 0.05 showed the presence of O2- adsorbed on sample surface at g = 2.02 and 2.00 and of Ce3+ with a lower symmetry at g = 1.97 and 1.94. Further increasing dopant content led to the disappearance of the signals for O2-. Impedance spectra showed the bulk and grain boundary conduction in the solid solutions. The bulk conduction exhibited a conductivity maximum and an activation energy minimum with increasing dopant content. Ce0.80Nd0.20O2-δ was determined to give promising conduction properties such as a relatively high conductivity of σ700 °C = 2.44 × 10-2 S cm-1 and moderate activation energy of Ea = 0.802 eV. The variations of conductivity and activation energy were explained in terms of relative content of oxygen vacancies VÖ and defect associations (CeCe'VÖ)/(NdCe'VÖ).
AB - Ce1-xNdxO2-δ (x = 0.05 to 0.55) nanocrystalline solid solutions were prepared by a sol-gel route. X-ray diffraction analysis showed that Ce1-xNdxO2-δ crystallized in a cubic fluorite structure. The lattice parameter for the solid solutions increased linearly with the dopant content. The solid solubility of Nd3+ in ceria lattice was determined to be about x = 0.40 in terms of the nearly constant lattice parameters at a dopant level larger than x = 0.40. First-order Raman spectra for Ce1-xNdxO2-δ at a lower dopant content exhibited one band associated with the F2g mode. At higher dopant contents, F2g mode became broadened and asymmetric, and a new broad band appeared at the higher frequency side of the F2g mode. This new band was assigned to the oxygen vacancies. The electron paramagnetic resonance spectrum for x = 0.05 showed the presence of O2- adsorbed on sample surface at g = 2.02 and 2.00 and of Ce3+ with a lower symmetry at g = 1.97 and 1.94. Further increasing dopant content led to the disappearance of the signals for O2-. Impedance spectra showed the bulk and grain boundary conduction in the solid solutions. The bulk conduction exhibited a conductivity maximum and an activation energy minimum with increasing dopant content. Ce0.80Nd0.20O2-δ was determined to give promising conduction properties such as a relatively high conductivity of σ700 °C = 2.44 × 10-2 S cm-1 and moderate activation energy of Ea = 0.802 eV. The variations of conductivity and activation energy were explained in terms of relative content of oxygen vacancies VÖ and defect associations (CeCe'VÖ)/(NdCe'VÖ).
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U2 - 10.1557/JMR.2001.0442
DO - 10.1557/JMR.2001.0442
M3 - Article
AN - SCOPUS:0035521917
VL - 16
SP - 3207
EP - 3213
JO - Journal of Materials Research
JF - Journal of Materials Research
SN - 0884-2914
IS - 11
ER -