Synthesis of stoichiometric hydroxyapatite nanoparticles via aqueous solution-precipitation at 37 °C

Abstract

Stoichiometric hydroxyapatite (HAp) nanoparticles were prepared by the solution-precipitation method at 37 °C. During the 72-h maturation period, the Ca/P molar ratio first rapidly increased to >1.6, and then reached 1.67 relatively slowly. The crystallite sizes of the stoichiometric HAp nanoparticles were estimated to be 11.0(3) and 25.7(3) nm from 300 and 002 diffractions, respectively. The crystallite size in the [001] direction continued to increase after the 72-h maturation period at a constant Ca/P molar ratio of 1.67. The obtained stoichiometric HAp nanoparticles also exhibited higher thermal stability than commercially available HAP-100 and prevented grain growth during sintering. This material is suitable for use in various sintering methods.