Fast mass interdiffusion in ceria/alumina composite

Gadolinium-doped ceria (CGO) presents unique processes at low oxygen partial pressure (pO(2) < 10(-12) atm) and low temperatures (T > 800 degrees C) such as faster mass diffusion, which are not observed in conventional sintering under ambient air conditions. In CGO/Al2O3 composites the resulting effects driven by such mass diffusion are low viscosity flows and high reactivity between phases, indicated by the formation of CeAlO3. This reaction is promoted by the high content of oxygen defects and the chemical reduction of Ce4+ cations to Ce3+ in CGO/Al2O3 composites under low temperature and low pO(2). In this work, a comparison is made between sintering CGO/Al2O3 under ambient air conditions and under low pO(2), focusing on densification, viscosity and the evolution of the microstructure