Low temperature processing of dense nanocrystalline scandia-doped zirconia (ScSZ) ceramics

Nanocrystalline scandia-doped zirconia (ScSZ) ceramics with a relative density of above 96% and an average grain size of ∼80 nm were prepared via pressureless sintering at 900 °C for 4 h in air. The starting powder synthesized by co-precipitation combined with supercritical fluid drying route is highly homogeneous and weakly agglomerated with crystallite size about 3 nm and specific surface area of 378 m2/g, and can be uniaxially pressed into highly homogeneous compacts. The excellent sinterability achieved in this work is mainly attributed to the small crystallite size with high surface area and the weak agglomeration. The very low sintering temperature achieved in the present work is of practical significance for suppressing the cubic phase to β-phase transition to some degree, eliminating the discontinuity in electrical conductivity and facilitating co-firing the ZrO2-based electrolytes with other SOFCs (solid oxide fuel cells) components.