Combustion synthesis and characterization of Cu–Sm co-doped CeO2 electrolytes

Abstract Nano-sized CSO (Ce 0.80 Sm 0.20 O 2− δ ) and CSCO (Ce 0.79 Sm 0.20 Cu 0.01 O 2− δ ) were synthesized by the PVA assisted combustion method, and then characterized by the structure of PVA–cation complexes and nano-powders, as well as mechanical and electrical performance after sintering. The results indicate that the PVA–cation complexes (PVA–(Ce 3+ ,Sm 3+ ) and PVA–(Ce 3+ ,Sm 3+ ,Cu 2+ )) were formed by coordinating metal cations to hydroxyl groups, as well as the COO −1 group derived from the oxidation of PVA with NO 3 −1 . Low temperatures (around 200 °C) caused intense combustion reactions, resulting in the direct crystallization of cubic fluorite nano-CSO (10–20 nm) and nano-CSCO (10–15 nm) crystals with homogeneous element distribution. This slight compositional modification of CSO by co-doping with 1 mol% CuO resulted in a significantly lowered densification temperature, as well as enhanced mechanical and electrical property. The strength improvement can be ascribed to the dense and fine-grained microstructure without normal grain coarsening, resulting in a transgranular-dominant fracture mode during strength testing.