Sintering behavior and thermal conductivity of Y2O3 fully stabilized HfO2 ceramics

Abstract

A series of Y2O3 fully stabilized HfO2 ceramics (Hf1−xYxO2−0.5x, x = 0.20, 0.24, 0.28, 0.32, 0.36 and 0.40) were synthesized by solid-state reaction at 1500 °C. The phase composition, thermal conductivity and sintering behavior at 1400 °C of the ceramic bulks were studied. The Hf1−xYxO2−0.5x ceramics were comprised of pure cubic phase with disordered fluorite structure. No phase transformation occurred in the ceramics with Y3+ doping concentration ranging from 0.24 to 0.36. Both Hf0.64Y0.36O1.82 and Hf0.6Y0.4O1.8 samples revealed the lowest grain growth rate when sintered at 1400 °C, indicating good resistance to sintering. However, the Vicker’s hardness and Young’s modulus after annealed for 96 h at 1400 °C for the Hf0.64Y0.36O1.82 sample were 8.97 and 200 GPa, respectively, much lower than those of the Hf0.6Y0.4O1.8 (14.51 and 237 GPa, respectively). The thermal conductivity of Hf1−xYxO2−0.5x first decreased and then increased slowly as the Y3+ content increased, and the associated mechanism was discussed.