A Facile One-Step Surfactant-Free and Low-Temperature Hydrothermal Method to Prepare Uniform 3D Structured Carbonated Apatite Flowers

In the absence of any surfactants, template supporting and structure-directing reagents, uniform 3D structured carbonated apatite flowers with exclusively nanosheet-constructed network morphology were synthesized via a low-temperature hydrothermal process, using Ca(NO3)2 and NH4H2PO4 as Ca and P sources, respectively, and urea as the homogeneous precipitation reagent. The as-obtained products were characterized by the X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), field emission transmission electron microscopy (FETEM) and Fourier transform infrared spectroscopy (FTIR). The results show that the as-obtained apatite flowers consisted of two-dimensional nanosheets with thickness about 75 nm, widths 200−1000 nm and lengths 1−5 μm, and the selected area electron diffraction (SAED) pattern reveals that the nanosheets in apatite are single crystalline. The uniform in size distribution and shape of the apatite flowers was probably attributed to the homogeneous precipitation effects, and the high crystallization of the products was attributed to the hydrothermal treatment. A possible self-assembled mechanism was preliminarily proposed for the formation of the novel 3D structures.