Tetragonal to Cubic Transformation of SiO₂-Stabilized ZrO₂ Polymorph through Dysprosium Substitutions

Partially stabilized tetragonal zirconia (t-ZrO₂) is of particular interest for hard tissue replacements. Aging-related failures of the ceramic associated with the gradual transformation from t-ZrO₂ to m-ZrO₂ (monoclinic zirconia) can lead to its premature removal from the implant site. In addition, monitoring the satisfactory performance of the implant throughout its lifespan without invasive techniques is a challenging task. The magnetic resonance imaging (MRI) contrast ability of dysprosium (Dy³⁺) is well-established. To this aim, varied levels of Dy³⁺ additions in the ZrO₂-SiO₂ binary oxide system were explored. The results indicate the effective role of Dy³⁺ in the formation of thermally and mechanically stable c-ZrO₂ (cubic zirconia) phase at higher temperatures. The presence of SiO₂ influenced the t-ZrO₂ stabilization, whereas Dy³⁺ tends to occupy the ZrO₂ lattice sites to induce c-ZrO₂ transition. Magnetic and MRI tests displayed the commendable contrast ability of Dy³⁺ stabilized ZrO₂-SiO₂ binary systems. Nanoindentation results demonstrate a remarkable enhancement of the mechanical properties.