Effect of TiO₂ addition on phase stability and sintering behavior of 1 mol%La₂O₃ -2 mol%Gd₂O₃-2 mol%Yb₂O₃-6 mol%Y₂O₃ co-doped ZrO₂

In this study, 1 mol%La2O3-2 mol%Gd2O3-2 mol%Yb2O3-6 mol%Y2O3 co-doped ZrO2 (LGYYSZ) with 0 mol%, 5 mol% and 10 mol% TiO2 additions were synthesised by solid-state reactions. The effect of TiO2 addition on the phase stability of LGYYSZ and its sintering behaviour at 1500 °C were investigated using XRD, SEM and EDS. The results show that the eutectic temperature of LGYYSZ decreases with increasing TiO2 content. SEM, EDS and XRD results show that the TiO2 addition is reacted with the La2O3 in LGYYSZ to form a orthorhombic La2Ti2O7 phase. When held at 1500 °C, La2Ti2O7 is precipitated on the surface of the samples by evaporation-condensation mechanism. This resulted in the anti-sintering properties of LGYYSZ at 1500 °C decreasing with increasing TiO2 content.