Synthesis of Micro and Nano-Sized Hydroxyapatite Fibers Through the Microwave Assisted Hydrothermal Method

The synthesis of hydroxyapatite (HAp) fibers was performed using a microwave assisted hydrothermal methodology. The actual reaction mixture was placed in a Teflon tube inside a microwave oven at 170 °C and 80 bar. Polycrystalline hydroxyapatite nanofibers were obtained under these operating conditions. The control on heating and cooling rates inside the reactor was critical as well as the use glutamic acid to guide the crystal growth. According to the results, the nanofibers showed a preferential crystalline orientation in the [300] but they grew in the [001] with high crystallinity and good purity. These nanofibers were closed packed inside hexagonal microfibers with a singular arrangement. Additionally, structural studies were done using X-ray diffraction by powders along with the chemical composition supported by infrared spectroscopy (FTIR) analyses. The morphology and microstructure characterization as well as crystalline features of the HAp nanocrystals were done through Scanning Electron Microscopy and High Resolution Electron Microscopy.