Preparation and characteristics of nanosized carbonated apatite by urea addition with coprecipitation method

Nanosized carbonated apatites (CAp) were prepared by coprecipitation method with urea addition at pH 8 and pH 12 with 12 hours aging, which resulted in needle-like and rod-like structures, respectively. From examining the XRD patterns, it was determined that the as-prepared powders contained no crystalline phase other than CAp. However, the powder prepared at pH 8 partially transforms to beta-tricalcium phosphate (beta-TCP) after heat treatment at 900 degrees C. Under beat treatment, powder prepared at pH 12 is more stable than powder prepared at pH 8. In addition, the as-prepared powders at pH 8 with 12 hours aging yield needle-like calcium deficient apatite (CDA) with substitution of CO32- for PO43- in low content. Their particle size is about 20 nm in width and 200-300 nm in length. The as-prepared powders at pH 12 for 12 hours aging result in rod-like nanostructures about 50 nm in diameter and 300 nm in length with 8.2 wt.% CO32-, which is similar 3 to human bone composition. Various characteristic analyses of CAp have been employed including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), and transmission electron microscopy (TEM). (c) 2008 Elsevier B.V. All rights reserved.