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Synthesis of Hydroxylapatite from Sand Dollar and β-Tricalcium Phosphate by Solid-State Method

Abstract Synthesis of porous hydroxylapatite from the sand dollar (Mellita eduardobarrosoi sp. nov.) and β-tricalcium phosphate (β-TCP) by solid-state reaction was performed. Reaction conditions were explored at different molar ratios of the precursors and at different temperatures. X-ray diffraction was used to determine the crystalline structure of the sample at molar ratio of 1.25 TCP : 1 sand dollar at 1473 K. The morphology of the product obtained under these conditions is a porous structure, which is a requirement for better clinical application of the hydroxylapatite as a biomaterial. Chemical analysis carried out by energy-dispersive spectroscopy on the product presented a molar ratio of Ca/P closer to the stoichiometric molar ratio of the pure hydroxylapatite. This crystalline structure was analyzed by transmission electron microscopy, and large single hydroxylapatite crystals were observed. Electron diffraction patterns in different directions are discussed.