Effects of 42khz Ultrasonic Treatment to the Crystallite Size and Morphology of Chemically-Prepared Carbonated-Hydroxyapatite

Background: Carbonate-substituted hydroxyapatites (carbonated-hydroxyapatites) are the primary mineral constituents of human and animal bone tissues. These materials are increasingly used in medical fields due to their biocompatibility and high bioactivity to osseous tissue. Objectives: To investigate the effect of ultrasonic treatment to the composition, crystallite size and morphology of the hydroxyapatite powders obtained using Ca(OH)2 and (NH4)2HPO4 using wet chemical precipitation technique with and without post-synthesis ultrasonic (42KHz) treatment, characterized using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Results: From FTIR spectra, carbonated hydroxyapatites were depicted with A and Btype dominated carbonate substitution, and crystal sizes equal to 0.537, 0.481, 0.453 and 0.432 for 0, 20, 30, 40 minutes ultrasonic treatment, respectively. The rate of change of crystallite size with ultrasonic exposure time is 0.00267 nm/minute. From SEM images, agglomerated nano-sized particles were observed with increasing time ultrasonic treatment. Conclusions: Ultrasonically-treated for 20 to 40 minutes and untreated hydroxyapatite powders were both A and B-type carbonate-substituted hydroxyapatite with B-type dominance. These hydroxyapatite powders exhibited crystallite size that decreases linearly (R 2 =0.994) from 0.537 to 0.432 nm with agglomeration of particles with increasing ultrasonic treatment.