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Effect of sintering temperature on the microstructure and ionic conductivity of Ce0.8Sm0.1Ba0.1O2-δ electrolyte

Anwar Mustafa (Universiti Kebangsaan Malaysia, Fuel Cell Institute, UKM Bangi, Selangor Darul Ehsan, Malaysia + National University of Sciences and Technology, U.S.-Pakistan Center for Advanced Studies in Energy (USPCAS-E), Islamabad, Pakistan)
Muhammed Ali S.A. (Universiti Kebangsaan Malaysia, Fuel Cell Institute, UKM Bangi, Selangor Darul Ehsan, Malaysia)
Abdalla Abdalla M. (Universiti Brunei Darussalam, Faculty of Integrated Technologies, JalanTunku Link, Gadong, Brunei Darussalam)
Somalu Rao Mahendra (Universiti Kebangsaan Malaysia, Fuel Cell Institute, UKM Bangi, Selangor Darul Ehsan, Malaysia)
Muchtar Andanastuti (Universiti Kebangsaan Malaysia, Fuel Cell Institute, UKM Bangi, Selangor Darul Ehsan, Malaysia + Universiti Kebangsaan Malaysia, Faculty of Engineering and Built Environment, Department of Mechanical and Materials Engineering, UKM Bangi, Selangor Darul Eh)

This study investigated the effects of sintering temperature on the microstructure and ionic conductivity of codoped ceria electrolyte with barium and samarium as dopants. The electrolyte (Ce0.8Sm0.1Ba0.1O2-δ) powder was synthesized using the citric acid-nitrate combustion method and calcined at 900°C for 5 h. The calcined electrolyte exhibited a cubic fluorite crystal structure with some impurity phases. The calcined powder was then pressed into cylindrical pellets using uniaxial die-pressing. The pellets were sintered at three different temperatures, i.e., 1200, 1300 and 1400°C for 5 h. Microstructural analysis of the pellets showed that the average grain size increased with the increase in sintering temperature. The sintered densities of the pellets were measured by Archimedes’ method, and the relative density values were within the range of 78%TD to 87%TD as the sintering temperature increased from 1200 to 1400°C. Electrochemical impedance spectroscopy analysis showed that conductivity increased with the increase in sintering temperature, but no considerable change in conductivity was observed for the pellets sintered at 1300 and 1400°C. The results revealed that the electrolyte pellet sintered at 1300°C exhibited the ionic conductivity of 0.005 S/cm with lowest activation energy of 0.7275 eV.

Keywords: CeO2, doping, sintering, microstructure, ionic conductivity