Study on La and Y co-doped ceria-based electrolyte materials

摘要

Co-doped ceria electrolytes of Ce_(0.8)La_(0.2-x)Y_xO_(1.9) (x=0.02, 0.06, 0.10, 0.14, 0.20) fine powders were prepared with the sol-gel method. The results of X-ray diffraction and Raman spectroscopy showed that all powders crystallite calcined at 800 deg C were single phase with cubic fluorite structure, the average crystallite sizes calculated by the Scherrer formula were between 27 and 34 nm, which was in good agreement with the results of TEM and particle size distribution measurements. The thermal expansion curves of Ce_(0.8)La_(0.2-x)Y_xO_(1.9) were measured and the thermal expansion coefficients (TEC) between 100 and 800 deg C were calculated. For the samples of Ce_(0.8)La_(0.2-x)Y_xO_(1.9) in the temperature range of 700-850 deg C, when x=0.06, 0.10 and 0.14, much higher ionic conductivity was observed than those of the singly doped ceria with same dopant concentration (20 percent trivalent rare earth) and when ;t=0.06, maximal conductivity is obtained. It suggested that co-doping with appropriate ratio of lanthanum and yttrium can further improve the electrical performance of ceria-based electrolytes, and these co-doped samples may be the better electrolytes for intermediate-temperature solid oxide fuel cells.