Flash sintering of variously doped-ceria materials

To obtain fully densified ceria-based materials a field-assisted sintering method was used thus allowing the consolidation at reduced temperature and shorter times. Variously-doped (Gd, Sm and Co/Gd) ceria powders were synthesized by co-precipitation method, shaped into pellets and sintered under the application of an electrical field in the range 25-250 V/cm within a specifically modified dilatometer. Morphological (SEM) and electrical (EIS spectroscopy) investigations were performed. Sintering under the effect of an electrical field allowed to obtain nearly fully dense pellets with nanometric grain size in the temperature range 450-600°C. In most cases a sudden Flash-Sintering phenomenon was revealed, it being strongly dependent on the electrical field intensity and dopant concentration. Field-assisted sintering is an effective method to produce fully dense doped ceria pellets at reduced temperature and very short time. Gd-doped ceria materials, sintered at 75 V/cm, show the best sintering behavior reaching 99.5% relative density which accounts for very high electrical conductivity (> 10-2 S/cm at 600°C).