Effect of Y doping on microstructure and thermophysical properties of yttria stabilized hafnia ceramics

Abstract A series of Y 2 O 3 -doped HfO 2 ceramics (Hf 1 -x Y x O 2-0.5 × , x = 0, 0.04, 0.08, 0.12, 0.16 and 0.2) were synthesized by solid-state reaction at 1600 °C. The microstructure, thermophysical properties and phase stability were investigated. Hf 1 -x Y x O 2–0.5 x ceramics were comprised of monoclinic (M) phase and cubic (C) phase when Y 3+ ion concentration ranged from 0.04 to 0.16. The thermal conductivity of Hf 1 -x Y x O 2–0.5 x ceramic decreased as Y 3+ ion concentration increased and Hf 0.8 Y 0.2 O 1.9 ceramic revealed the lowest thermal conductivity of ~ 1.8 W/m*K at 1200 °C. The average thermal expansion coefficient (TEC) of Hf 1 -x Y x O 2–0.5 x between 200 °C and 1300 °C increased with the Y 3+ ion concentration. Hf 0.8 Y 0.2 O 1.9 yielded the highest TEC of ~ 10.4 × 10 −6 K −1 while keeping good phase stability between room temperature and 1600 °C.