Stabilization of a t-ZrO₂ polymorph in a glassy SiO₂ matrix at elevated temperatures accomplished by ceria additions

Glass-ceramic composites are considered important candidates for load bearing orthopaedic applications owing to their combined salient features of bioactivity and mechanical strength. Herein, we report the impact of ceria (CeO₂) additions on the structural and mechanical behaviour of ZrO₂-SiO₂ binary oxides as a glass-ceramic composite for hard tissue replacements. A wide range of ceria additions to the ZrO₂-SiO₂ system have been performed via sol-gel synthesis. The structural behaviour of the synthesized compositions is investigated at elevated temperatures using a combination of XRD, Raman spectroscopy, TEM and SEM. The stabilization of tetragonal zirconia (t-ZrO₂) and CeO₂ in the presence of an amorphous SiO₂ matrix under heat treatment up to 1300 °C was confirmed. The t-ZrO₂ phase is stabilised through Ce⁴⁺ substitution up to 20 wt% CeO₂ additions, and above this CeO₂ crystallization occurs in the amorphous matrix. The morphological and mechanical behaviour of the ceramic reinforced glass matrix is presented with the CeO₂ stabilised system showing mechanical properties comparable with commercial biomaterial systems.