Controlled Crystallization of Calcium Phosphate Apatites

The growing necessity of biomaterials has increased the interest in calcium phosphates, particularly apatites. Small differences in stoichiometry, crystallinity, morphology, etc. could contribute to the different clinical behaviors observed, so perfect control of the synthesis parameters and their influence in the characteristics of the samples is a must. In the present work, a crystallization set able to produce massive and reproducible quantities of different calcium phosphates is presented. Apatites with different stoichiometries and morphologies are prepared, and the effects of varying synthesis conditions are analyzed. Temperatures in the range 25−37 °C are necessary to obtain apatites with crystal sizes in the range of adult human bone. Longer reaction times produce increased Ca/P ratios. Aging of the precipitated powder can lead to the incorporation of minor quantities of carbonate. It is possible to force the incorporation of carbonate ions into the apatitic structure without introducing monovalent cations.