Highly porous Sr-doped TiO2 ceramics maintain compressive strength after grain boundary corrosion

Abstract

Maintaining sufficient mechanical support during bone healing is an essential property for ceramic bone scaffolds. However, grain boundary (GB) dissolution may compromise the mechanical strength of polycrystalline ceramics in the physiological environment. Therefore, we investigated the GB formation and its impact on the compressive strength and corrosion behavior in TiO2 scaffolds doped with calcium and strontium. To alter the GB composition and densification process, sintering conditions were altered. Prolonged sintering times and increased sintering temperature led to improved densification and increased strength in Ca-doped scaffolds. However, dissolution of the resulting amorphous GBs caused a significant loss of compressive strength when exposed to an acidic environment. In contrast, a crystalline SrTiO3 GB phase present in Sr-doped scaffolds, for which increased sintering temperature combined with rapid cooling led to a significantly improved compressive strength. Formation of SrTiO3 crystals in the GBs maintained the strength for over 4 weeks in an acidic environment.