Synthesis of pure hydroxyapatite by ion exchange reaction

Abstract

An ion-exchange reaction for the synthesis of hydroxyapatite (HAP) in a constant alkaline medium using preliminary dry homogenization is proposed in this work. Sodium hydrogen phosphate Na2HPO4, calcium chloride CaCl2 and calcium hydroxide Ca(OH)2 were chosen as precursors. Studies carried out by methods of X-ray phase analysis, scanning electron and transmission microscopy showed that the material obtained is a singlephase hydroxyapatite powder with a Ca/P ratio close to 1.67. It was found that the particles of HAP powder obtained as a result of synthesis with subsequent washing have the shape of needles with a thickness of 10 to 40 nm and a length of 30 to 200 nm. Annealing of the powder at a temperature of 700 °C leads to agglomeration of particles, as well as to rounding of their shape