Gadolinium Doping in Zirconia-Toughened Alumina Systems and Their Structural, Mechanical, and Aging Behavior...

A series of Gd³⁺ dopings in zirconia-toughened alumina (ZTA) systems were undertaken to explore the resultant structural, morphological, hydrothermal aging, and mechanical behavior and imaging contrast abilities. The results from the characterization techniques demonstrate the significance of Gd³⁺ in preserving the structural stability of ZTA systems. ZTA undergoes phase degradation with 10 wt % Gd³⁺ at 1400 °C, while the 100 wt % Gd³⁺ yields GdAlO₃ even at 1200 °C. Gd³⁺ doping at the intermediate level preserves the structural stability of ZTA systems until 1400 °C. Gd³⁺ occupies the ZrO₂ lattice, and its gradual accumulation induces tetragonal ZrO₂ (t-ZrO₂) to cubic ZrO₂ (c-ZrO₂) phase transition. α-Al₂O₃ crystallizes at 1200 °C and remains unperturbed except for its reaction with the free Gd³⁺ ions to yield GdAlO₃. Aging studies and mechanical tests signify the impeccable role of Gd³⁺ in ZTA systems to resist phase degradation. Further, the imaging contrast ability of ZTA systems due to Gd³⁺ doping is verified from the in vitro magnetic resonance imaging (MRI) tests.