Fast mass interdiffusion in ceria/alumina composite

Abstract

Gadolinium-doped ceria (CGO) presents unique processes at low oxygen partial pressure (pO₂ < 10⁻¹² atm) and low temperatures (T > 800 °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 pO₂. In this work, a comparison is made between sintering CGO/Al₂O₃ under ambient air conditions and under low pO₂, focusing on densification, viscosity and the evolution of the microstructure.