Forming Mechanism of TiO_2 Nanofibres Prepared by Hydrothermal Method

The TiO_2 nanofibres with the diameter ofφ20-30nm and the length of micron-dimension were successfully synthesized by hydrothermal method.Their crystalline structure,morphology and chemical composition were characterized by the transmission electron microscope(TEM),X-ray dif- fraction patterns(XRD),infrared spectrum(IR),etc.The forming mechanism of the TiO_2 nanofibres and the effects of pH value in the process of washing on the nanofibres structure were investigated and analyzed,respectively.The results indicate that the forming mechanism of the TiO_2 nanofibres can be described as following: K_2Ti_6O_(13)nanoparticles are initially formed in alkaline solution using anatase nanoparticles as raw materials,and then gradually grown to nanofibres along a certain crystalline axis obeyed the dissolution-growth mechanism.The pH value of washing solution has a significant influence on the structure and composition of the products.The nanofibres of K_2Ti_6O_(13),H_2Ti_3O_7 and TiO_2 can be obtained by the controlling of the pH value of washing solutions and heat-treatment temperature. The products,washed in solution with pH=7 and dried at 80℃,form the nanofibres of H_2Ti_3O_7,which is subsequently calcined to form TiO_2 nanofibres at 400℃.