Abstract
Achieving simultaneous enhancement of Vickers hardness and fracture toughness remains a critical challenge in designing oxide ceramic materials due to their partially antagonistic nature. In this study, we address this trade-off by tailoring the microstructure of zirconia (ZrO(2)) ceramics through Y(2)O(3) doping and high-pressure high-temperature (HPHT) sintering. Nanostructured composites were synthesized using 50 nm monoclinic ZrO(2) and varying Y(2)O(3) contents (3, 5, and 7 mol%) under 5 GPa at temperatures ranging from 400 to 2000 °C. Among them, 3 mol% Y(2)O(3)-doped zirconia (3Y-PSZ) sintered at 1200 °C achieved a well-balanced mechanical performance, with a Vickers hardness of 11.6 GPa and a fracture toughness of 9.26 MPa·m(1/2). These results demonstrate that it is feasible to retain a high hardness while significantly enhancing toughness by controlling phase composition and grain refinement under HPHT conditions. This work offers valuable insights into microstructural optimization strategies for zirconia-based ceramics aiming to overcome the conventional hardness-toughness trade-off.