Influence of Y2O3 and Ta2O5 Co-doping on Microstructure and Thermal Conductivity of Gd2Zr2O7 Ceramics

Rare earth zirconates (RE2Zr2O7) are considered as a class of potential high-temperature structural materials. In this paper, a series of Y2O3 and Ta2O5 co-doped Gd2Zr2O7 [(Gd1−xYx)2(Zr1−xTax)2O7+x, x = 0, 0.1, 0.2, 0.3, 0.4] ceramics were prepared by solid-state reaction sintering in order to clarify the influence of Y2O3 and Ta2O5 co-doped on microstructure, Young’s modulus and thermal conductivity. The results showed that Y2O3 and Ta2O5 co-doped Gd2Zr2O7 exhibited a single pyrochlore structure, and a small amount of Y3+ ions were doped into the Zr4+ ions lattice. The Young’s moduli of doped Gd2Zr2O7 ceramics slightly change with the increase in Y2O3 and Ta2O5 doping concentration. The minimum thermal conductivities of the specimens were obtained at 800 °C. The thermal conductivity of doped Gd2Zr2O7 with x = 0.3 is lower than that of others among the doped specimens, which is around 1.41 W m−1 K−1 at 800 °C. In addition, (Gd0.7Y0.3)2(Zr0.7Ta0.3)2O7.3 ceramic exhibits excellent phase stability from room temperature to 1550 °C.