Utility of Ce_(0.8)M_(0.2)O_(1.9), Ce_(0.8)M_(0.15)Y_(0.05)O_(1.9), M = Gd, Sm powders synthesized by aerosol decomposition method in solid oxide fuel cell technology

摘要

Singly-doped and co-doped ceria powders with the formula Ce_(0.8)M_(0.2)O_(1.9) or Ce_(0.8)M_(0.15)Y_(0.05)O_(1.9), M = Gd, Sm were synthesized using the spray pyrolysis method at 700℃. X-ray diffraction analysis showed that all obtained powders were pure cubic CeO_2-based solid solutions. Scanning and transmission electron microscopy were used to characterize the morphology of CeO_2-based powders. It was found that the prepared powders were composed of fully spherical particles ranging in size from ～0.1 to 1.3 μm. Additional heat treatment of these powders in the temperature range of 700-1000℃ resulted only in small increased particle size. The particles lost their spherical shape at temperatures above 1200℃. A study of sintering activity of powders prepared in this way was also performed, using the dilatometric method. Finally, CeO_2-based samples were sintered at 1500℃ in air for 2 h. The ionic conductivity of Ce_(0.8)M_(0.2)O_(1.9) and Ce_(0.8)M_(0.15)Y_(0.05)O_(1.9) M = Gd, Sm sintered samples were studied by AC impedance spectroscopy. It was found that the partial substitution of Y~(3+) for Gd~(3+) resulted in increased ionic conductivity of Ce_(0.8)M_(0.15)Y_(0.05)O_(1.9), M = Gd, Sm compared to Ce_(0.8)M_(0.2)O_(1.9), M = Gd, Sm. The possibility of using spherical CeO_2-based powders for the preparation of screen-printable paste (to be used in turn for the deposition of gas-tight electrolyte films for anode-supported solid oxide fuel cells) was also investigated. The performance of single anode supported solid oxide fuel cells, involving singly doped ceria as Ce_(0.8)Sm_(0.2)O_(1.9) or Ce_(0.8)Sm_(0.15)Y_(0.05)O_(1.9) as oxide electrolytes fueled with gaseous hydrogen, was presented and analyzed. The authors also pointed out that the co-doped ceria electrolytes Ce_(0.8)Sm_(0.15)Y_(0.05)O_(1.9), M = Gd, Sm seem to be also promising oxide electrolytes for construction solid oxide fuel cells, which utilized solid carbon as fuel.