Carbonate hydroxyapatite and silicon-substituted carbonate hydroxyapatite: Synthesis, mechanical properties, and solubility evaluations

Abstract

The present study investigates the chemical composition, solubility, and physical and mechanical properties of carbonate hydroxyapatite (COp) and silicon-substituted carbonate hydroxyapatite (Si-COp) which have been prepared by a simple precipitation method. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray fluorescence (XRF) spectroscopy, and inductively coupled plasma (ICP) techniques were used to characterize the formation of COp and Si-COp. The results revealed that the silicate (SiO44-) and carbonate (CO32-) ions competed to occupy the phosphate (PO43-) site and also entered simultaneously into the hydroxyapatite structure. The Si-substituted COp reduced the powder crystallinity and promoted ion release which resulted in a better solubility compared to that of Si-free COp. The mean particle size of Si-COp was much finer than that of COp. At 750°C heat-treatment temperature, the diametral tensile strengths (DTS) of Si-COp and COp were about 10.8±0.3 and 11.8±0.4 MPa, respectively. © 2014 L. T. Bang et al.