Thesis (M.Sc.)--Chulalongkorn University, 2004

In this research, solid oxide fuel cell electrolytes were fabricated by aqueous tape casting technique. The basic compositions for SOFC electrolyte systems were focussed on yttiria-stabilized zirconia (YSZ) system and the preliminary investigations on the ceria-based system with Gd[subscript 2]O[subscript 3] addition was also performed. The powders used in this study were from different sources. ZrO[subscript 2]-based system doped with 3, 8, and 10 mol% of Y[subscript 2]O[subscript 3] were used in this research work, and 8YSZ electrolyte tape illustrated the desirable properties. The grain size of the sintered electrolyte tapes was in the range of 0.5-1 mm with 98-99% of theoretical density. Phase and crystal structure showed the pure cubic fluorite structure for 8-10 mol% Y[subscript 2]O[subscript 3] doped ZrO[subscript 2] and tetragonal phase for 3 mol% doped. The electrolyte tapes sintered at 1450 ํC for 4 hours had the highest ionic conductivityof 30.11 x 10[superscript -3] S/cm. The flexural strengths were in the range of 100-180 MPa for 8-10 mol% YSZ, and 400-680 MPa for 3 mol% YSZ