Phase transition in ceria alumina |
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Authors: | Saba Beg Sadaf Haneef |
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Institution: | 1.Physical Chemistry Division, Department of Chemistry,Aligarh Muslim University,Aligarh,India |
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Abstract: | Al-doped CeO2 samples were prepared by conventional solid state reaction. The electrical conductivity of CeO2 doped with Al2O3 has been studied at different temperatures for various molar ratios. The isothermal conductivity increases with dopant concentration
due to the vacancy migration phenomenon induced by doping. It has been found that the conductivity increases and shows a jump
from 450 to 520°C due to the phase transition of ceria from cubic to orthorhombic type. A slight deflection is seen for 0.5
and 0.6 moles of alumina at about 250°C due to its phase transition from γ to α type. AC impedance measurements proved that
the oxide ion conductivity predominantly arises from the grain and grain boundary contribution as two well defined semi-circles
are clearly seen. The sample characterization and the study of phase transition changes were done by using X-ray diffraction
analysis, Fourier transform infrared spectral and differential scanning calorimetry (DSC) measurements. On increasing the
concentration of dopant, the transition temperature shifts towards lower side which is confirmed by DSC as well as conductivity
measurements. |
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