Effect of zinc oxide doping on the grain boundary conductivity of Ce0.8Ln0.2O1.9 ceramics (Ln = Y, Sm, Gd)

► The addition of 1 mol% ZnO significantly increases both the apparent and specific grain boundary conductivities of Ce0.8Ln0.2O1.9 (Ln = Y, Sm, Gd). ► The phenomenon of Si-enrichment was observed on the surfaces of some ZnO-added samples. ► 1 mol% ZnO-doping promotes densification, and reduces the sintering temperature for 200 °C.