A systematic examination of the morphology of hydroxyapatite in the presence of citrate

In this paper, a systematic study of the influence of various experimental parameters on morphology and size of hydroxyapatite (HAp) was investigated under hydrothermal conditions in the presence of sodium citrate. The Ca/citrate ratio, the pH value and the reaction temperature were important factors for the morphologenesis of HAp. The morphologies of the products were transformed from nanoparticles (plate, rod) to microparticles (dumbbell, flower and sphere like particle) accompanied with the alteration of experimental conditions. The interaction between citrate and HAp crystals was carefully demonstrated, and a possible formation mechanism of different nanostructures was proposed.