Solvothermal preparation of hydroxyapatite microtubes in water/N,N-dimethylformamide mixed solvents

Hydroxyapatite microtubes have been successfully prepared using CaCl2 and NaH2PO4 in mixed solvents of water/N,N-dimethylformamide (DMF) by a solvothermal method at 160 °C for 24 h. The effects of the solvothermal time and concentration of DMF on the product were investigated. When the solvothermal time was 2 h, the sample consisted of monetite with a triclinic structure. When the solvothermal time was increased to 5 h, the mixed phases of monetite and HA were obtained. A single phase of crystalline HA with a hexagonal structure was obtained for 12 h. The products were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and fourier transform infrared (FTIR).