Effects of ultrasonic agitation time on wet chemical synthesis of nanohydroxyapatite

In this study, the synthesis of the nanohydroxyapatite (nHAp) powders by way of wet chemical method is reported. Calcium nitrate tetrahydrate (Ca(NO3)₂·H₂O) and dibasic ammonium phosphate ((NH4)₂HPO₄) were used as calcium and phosphorus sources, respectively. The effect of ultrasonic agitation time has been systematically studied between 30 and 150 min at the temperature of 70°C. Structural, morphological, spectroscopic and thermal analysis have been carried out by way of X-ray powder diffraction, scanning electron microscopy, Fourier-transform infrared spectroscopy and Raman spectroscopy and thermogravimetry–differential scanning calorimetry analysis. It is shown that the ultrasonic agitation conditions significantly affect the crystallite size, dislocation density and microstrain of the powders calculated by way of the Debye–Scherrer formula. Thermal analyses reveal that the ultrasonic agitation treatment has a very beneficial effect on the fabrication of the powders by the wet chemical method due to the inhibition of physisorbed and chemisorbed water and the calcium deficiency. Magnetic stirring treatment is found to lead to larger nHAp nanoparticle agglomerations due to more water absorption. The results offer a promising route towards the scalable synthesis of the pure-phase nHAp powders with controllable structural and morphological properties, which could be useful in various types of basic and applied research on HAp-based materials.