Influence of synthesis on the grain size distribution of Ca5GeP2O12

Modern implants are often based on silicon-doped hydroxyapatite for enhanced biological activity. Such materials still have drawbacks, such as high probability of bacterial infections on their surface during surgery. In this work, we obtained germanium-substituted calcium phosphates, which are isostructural to silicon-substituted hydroxyapatite and whitlockite. Additionally, they potentially possess antibacterial properties. We obtained Ge-substituted phosphate composition Ca5GeP2O12 by solid-state, sol-gel, and combustion synthesis. The samples were analyzed using powder X-ray diffraction. Solid-phase synthesis leads to the formation of whitlockite, whereas synthesis in solution leads to the formation of hydroxyapatite. The calculation of the grain size distribution shows that the smallest particles are formed when combustion synthesis is used, and the largest particles are obtained during solid-phase synthesis. This is correlated with the expected influence of stirring and temperature factors on the reaction path.