Low temperature fabrication of dense gadolinia-doped ceria electrolyte with enhanced electrical conductivity

By combination of supercritical drying route and coprecipitation synthesis method, ultrafine Ce0.8Gd0.2O1.9 (GDC20) nano-powders are successfully prepared using (NH4)2CO3 as the precipitant. The as-synthesized powder has a specific surface area of 113.4 m2 g−1 and an average crystalline size of ∼6 nm after calcination at 400 °C, together with other favorable properties like high dispersibility, weak agglomeration and remarkable flowability. The powder shows high sintering activity, where the relative density reaches ∼99.9% with an average grain size of ∼100 nm after sintered at 900 °C for 4 h. Low temperature sintering not only suppresses grain growth but also improves electrical performance of the electrolyte. The sample sintered at 900 °C exhibits high electrical conductivity of 5.39 S m−1 at 700 °C, which is superior to most of the reported ceria-based electrolyte.