Sintering behavior of samarium doped ceria under DC electrical field

Samarium doped ceria (Ce0.8Sm0.2O1.9) can be sintered to a dense state at low temperatures under the DC electric field. It was shown that the flash onset furnace temperature decreased from 756 degrees C to 578 degrees C under the electric field ranging from 60 to 120 V cm(-1). Specimens under different current densities and electrical fields were obtained during a controlled flash sintering process, the current density increased stepwise by 2.5 A cm(-2) per step with an interval of 1 min in this process. The microstructural analysis suggested that the current density has a great influence on controlling the final density of sintered bodies and the grain size of the flash sintered specimens which is much smaller than that obtained via conventional sintering routes. The specimen temperature was estimated by means of black-body radiation model and the feedback loop during flash sintering was found. More importantly, the finite element simulation results indicated a significant thermal gradient between the surface and interior of the sample. Consequently, the temperature gradient, density gradient and particle size gradient were observed in sintered bodies.