Vat photopolymerization of Nb₂O₅-Doped 3Y-TZP ceramics: Correlation between microstructure, mechanical properties,...

In this study, 3 mol% yttria-stabilized tetragonal zirconia polycrystals (3Y-TZP) ceramics with four levels of Niobium pentoxide (Nb₂O₅) doping (0, 0.3, 0.6, and 1.2 wt%) were fabricated using vat photopolymerization (VPP) and subsequently sintered at 1500 °C. The influence of Nb₂O₅ doping on the phase composition, microstructure, mechanical properties, and hydrothermal aging behavior of the ceramics was investigated. All ceramic pastes showed similar rheological behavior, and no significant difference were observed in shrinkage during sintering. X-ray diffraction revealed an increase in monoclinic phase content with increasing Nb₂O₅ doping (from 1.03 wt% to 37.60 wt% m-ZrO₂). SEM analysis showed grain growth from 0.433 to 0.558 μm with increasing dopant content. Mechanical testing revealed that low Nb₂O₅ doping (0.3 wt%) significantly improved fracture toughness (from 4.36 to 7.52 MPa m¹/²), while higher doping levels led to a decline in flexural strength (from 999.68 to 380.23 MPa) and hardness (from 12.71 to 9.51 GPa). Accelerated aging tests (134 °C/0.2 MPa, for up to 50 h) demonstrated that Nb₂O₅ addition promoted t→m transformation, increasing monoclinic content and surface roughness, ultimately reduced aging stability. These results highlight a trade-off between improved toughness and hydrothermal degradation in Nb₂O₅-doped 3Y-TZP ceramics prepared by VPP.