Processing and Properties of Scandia-doped Zirconia Electrolyte for Intermediate Temperature SOFC

Lower temperature operation of a solid oxide fuel cell (SOFC) is highly desirable for achieving lower cost because less expensive metallic materials can be used for the complete system. Towards this goal, use of a more conducting electrolyte based on scandia-doped zirconia is a promising choice of an electrolyte. A composition with 9.2 mole% Sc2O3 in ZrO2 (scandia stabilized zirconia) is studied as an electrolyte for the SOFC operation at intermediate temperature range of 600-800 degrees C. The electrolyte powder is prepared by a gel-combustion technique using citric acid as the fuel. The reaction product is calcined, tape cast, sintered, and characterized by x-ray diffraction. A single-phase cubic structure belonging to the cubic stabilized zirconia phase is obtained with a lattice parameter of a = 5.086 angstrom and coefficient of thermal expansion in the range of 9.9 to 10.2 ppm/degrees C.