Effect of titania concentration on the grain boundary conductivity of Ce0.8Gd0.2O1.9 electrolyte

The effect of titania (TiO2) addition on the densification, crystal structure and electrical property of Ce0.8Gd0.2O1.9 (GDC) are examined. TiO2 addition reduces GDC sintering temperature by ∼200 °C and considerably improves grain boundary conduction. The minimum grain boundary resistivity is obtained at 0.8 mol% TiO2 concentration. XRD analysis suggests that the solubility limit of TiO2 in GDC is ∼0.6 mol%. The optimum doping level (0.8 mol%) is slightly higher than the solubility limit (0.6 mol%), which implies that a small amounts of TiO2 (∼0.2 mol%) at the grain boundaries benefits the grain–boundary conduction.

► TiO2 addition reduces the sintering temperature of Ce0.8Gd0.2O1.9 (GDC) by ∼200 °C.
► TiO2 addition improves the grain boundary conduction of GDC significantly.
► The optimum doping level of TiO2 in GDC is 0.8 mol%.
► The solubility limit of TiO2 in GDC is ∼0.6 mol% at 1400 °C.
► The optimum concentration of TiO2 exists at grain boundaries of GDC is ∼0.2 mol%.