Influence of carbonate ion in the crystallization medium on the formation and chemical composition of CaHA–SrHA solid solutions

• The CaHA–SrHA solid solutions were synthesized by precipitation at 90 °C.
• Synthesis was carried out from water solutions with atomic C/P = 0; 0.05 and 0.1.
• Precipitates were studied by XRD, IRS and different chemical analyses.
• Presence of CO32− ions in solution promotes the incorporation of Sr in the apatite.
• (Ca,Sr)HAs are more defective than mainly calcium or mainly strontium apatites.

The study of the influence of carbonate ions in a solution to Sr-distribution in system «solution–crystal» and to ion substitutions and the non-stoichiometry of formed CaHA–SrHA solid solutions was carried out. The CaHA–SrHA solid solutions were synthesized by precipitation from aqueous solutions with the atomic C/P ratio equal to 0, 0.05 and 0.1 at T = 90 °C. Resulting precipitates were studied using various methods including X-ray powder diffraction, infrared spectroscopy and different chemical analyses.The results of the study have shown that in the range of values of (Ca + Sr)/P in the water solution from 40% to 85%, the presence of carbonate ions (C/P = 0.05–0.1) promotes the incorporation of strontium in the apatite. Crystalline apatite solid solutions formed from water solutions of such composition are more defective compared to apatites that are mainly calcium or strontium. They are characterized by a smaller size coherence scattering domain length along [0 0 1] direction and a greater number of carbonate ions, water molecules and vacancies at the Ca-sites.