Influence of process conditions on hydroxyapatite crystallinity obtained by direct crystallization

Crystallization from solutions was applied to produce stoichiometric and crystalline hydroxyapatite (HAP) suitable for use as a biomaterial. This was accomplished by keeping a low supersaturation through the following procedure: semi-continuous operating mode, slow reactant addition rate and addition of a calcium complexing agent. A high temperature (90 °C) and probably carbonate incorporation also favored the formation of a well crystallized material. A qualitative correlation was found between the supersaturation and HAP properties such as crystallinity and particle size
Near-stoichiometric and well crystallized hydroxyapatite was obtained by means of a semi-continuous procedure. Changes in crystallinity and particle size due to varying reagent addition rate, base concentration and pH were consistent with the corresponding changes in the su- Financiadora de Estudos e Projetos do Ministério de Ciência e Tecnologia, Brazil - and CYTED - Programa Iberoamericano de Ciencia y Tecnologia para el Desarollo, proj. VIII.6, Spain - for the financial support.