Densification and Grain Growth during Early-stage Sintering of Ce0.9Gd0.1O1.95-δ in Reducing Atmosphere

The present work investigates the processes of densification and grain growth of Ce0.9Gd0.1O1.95-δ (CGO10) during sintering in reducing atmosphere. Sintering variables were experimentally characterized and analyzed using defect chemistry and sintering constitutive laws. Based on the achieved results, the grain size-relative density trajectory, the densification rate, and the grain-growth rate were determined.

The activation energies for densification and grain growth were evaluated, and the dominant densification mechanism was clarified. For comparison, the densification behavior of CGO10 during air-sintering was also studied. Accelerated densification was found in earlystage reducing-sintering of CGO10.

This might be attributed to the oxygen vacancies generated by the reduction of Ce4+ to Ce3+ in reducing atmosphere, which facilitates the diffusion of ions through the lattice. The densification activation energy of CGO10 in reducing-sintering was evaluated as 290±20 KJ/mol in the relative density range of 0.64 to 0.82, which was much smaller than that of air-sintering (770±40 KJ/mol).

The grain-growth activation energy of CGO10 in reducing-sintering was evaluated as 280±20 KJ/mol in the grain size range of 0.34 to 0.70 μm. The present work describes a systematic investigation of reducing-sintering behavior of CGO10, which contributes to the first known determination of the fundamental parameters associated with densification and grain growth during early-stage sintering of CGO10 in reducing atmosphere.