Ce0.8(Sm1-xSrx)0.2O2-δ electrolyte preparation and properties
Sr and Sm co-doped Ce0.8(Sm1-xSrx)0.2O2-δ electrolyte powders were prepared by precipitation method.The roasted powders were moulded and then sintered in air at 1 500℃for 5 h to obtain ceramic samples.The thermal decomposition process of the precursors was investigated by thermogravimetric analysis(TG-DSC).X-ray diffractometer(XRD),scanning electron microscope(SEM),alternating current impedance spectroscopy(AC),and thermal expansion meter were used to characterise the crystal structure,micro-morphology,electrical properties,and thermal expansion coefficient(TEC)of the samples.The results show that the calcination temperature of Ce0.8(Sm1-xSrx)0.2O2-δ precursor is determined to be 650℃by TG-DSC analysis respectively.The Ce0.8(Sm1-xSrx)0.2O2-δ powder calcined at 650℃for 2 h has a single cubic fluorite structure.The samples are denser after sintering at 1 500℃,with a few pores on the surface of the samples and overfiring,and their relative densities are all higher than 92% .The sample with composition Ce0.8(Sm0.8Sr0.2)0.2O2-δ has a maximum conductivity of 5.4×10-2 S/cm at 700℃.With the increase of Sr2+doping,the thermal expansion coefficient of the sample increases and then decreases,with the thermal expansion coefficient of(10.16-11.38)×10-6 K-1.Ce0.8(Sm0.8Sr0.2)0.2O2-δ is expected to be used as an electrolyte for intermediate-temperature SOFC.
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