Peroxide-doped apatites: Preparation and effect of synthesis parameters

This contribution focused on the preparation of peroxide-doped calcium phosphate apatites — in view of potential uses as bioactive bioceramics with antimicrobial functions, and on their main physico-chemical characteristics. Two synthesis routes were investigated. First, the hydrolysis of β-TCP in the presence of H2O2 was followed. However, only elevated concentrations in H2O2 in the medium or temperatures around 150 °C allowed us to reach the complete β-TCP-to-apatite hydrolysis process, and the obtained samples exhibited a high crystallinity state with no non-apatitic chemical environments. The second protocol tested consisted in the direct apatite precipitation in the presence of H2O2 in the medium (at room temperature). This protocol led to single-phased nanocrystalline apatites, and our data indicate that part of the apatitic OH− ions were substituted by oxygenated species, and typically by peroxide ions (quantified). Physico-chemical modifications in the form of an improvement in crystallinity state, an increase in unit cell volume, and the presence of additional Raman bands were noticed and discussed.