Improvement on the phase stability, mechanical properties and thermal insulation of Y2O3-stabilized ZrO2 by Gd2O3 and Yb2O3 co-doping

Gd2O3 and Yb2O3 co-doped 3.5 mol% Y2O3–ZrO2 and conventional 3.5 mol% Y2O3–ZrO2 (YSZ) powders were synthesized by solid state reaction. The objective of this study was to improve the phase stability, mechanical properties and thermal insulation of YSZ. After heat treatment at 1500 °C for 10 h, 1 mol% Gd2O3–1 mol% Yb2O3 co-doped YSZ (1Gd1Yb-YSZ) had higher resistance to destabilization of metastable tetragonal phase than YSZ. The hardness of 5 mol% Gd2O3–1 mol% Yb2O3 co-doped YSZ (5Gd1Yb-YSZ) was higher than that of YSZ. Compared with YSZ, 1Gd1Yb-YSZ and 5Gd1Yb-YSZ exhibited lower thermal conductivity and shorter phonon mean free path. At 1300 °C, the thermal conductivity of 5Gd1Yb-YSZ was 1.23 W/m K, nearly 25% lower than that of YSZ (1.62 W/m K). Gd2O3 and Yb2O3 co-doped YSZ can be explored as a candidate material for thermal barrier coating applications.