Hydrothermal Synthesis And Optical Limiting Effects Of Low-dimension Sodium Titanate Materials

The optical limiting material which based on the nonlinear optical theory,have the potential for protecting optical sensors and possibly even human eyes from laser-pulse damage.Titania/titanate,as a new emerging semiconductor-based optical limiting material,has become an active and interesting subject,because of the unique phase structure and optical physical properties.Titania/titanates exhibit numerous phases,such like Na2Ti2O5,Na2Ti3O7,and TiO2(rutile,anatase,and brookite).Titania/titanate also exhibit different morphologies,such like one dimensional nanomaterials:nanotube,nanorod and two dimensional nanomaterials:nanosheet,nanoplate.Titania/titanate nanomaterials with different phases and morphologies have different optical properties.Hence,studying the optical limiting effects of Titania/titanate nanomaterials with different phases and morphologies will make a great significance to science.In this paper,titanium dioxide P25 and tetrabutyl titanate were chosen as the source of titanium.Titanates with different morphologies were prepared by the alkaline hydrothermal treatment of titanium dioxide P25 at different reaction time;titania/titanate with different phases and morphologies were prepared by acidic.post-treatment at different HC1 concentration;TiO2 nanorod array with different morphologies were prepared by acid hydrothermal treatment of FTO conductive glass.The products were characterized by X-ray diffraction,scanning electron microscopy,transmission electron microscopy and ultraviolet-visible absorbance.The influence of different factors on morphology,and phase composition of titania/titanate nanostruetures were investigated.Z-scan technology was used to study the optical limiting effects of Titania/titanate nanomaterials.The results were as follows:(1)Titanate nanobelt started split into nanowire with the increase of reaction time.Titanate nanobelt exhibited the best optical limiting effect which contained a few fragmentation nanobelts.(2)The phase and morphology of the hydrothermally prepared titanate were influenced by post?treatment HCl washing.The phase transformation rate increased with increasing HCl concentration.Titanate transformed to rutile occurred via the rearrangement of TiO6 octahedra.This was coupled with a change in morphology from nanotubes to nanosheets and nanoparticles.After treatment of 0.55 mol·L-1 HCl,the sample has the best optical limiting effect.(3)FTO conductive glass was chosen as the substrate,tetrabutyl titanate was chosen as the source of titanium.When growth was conducted by adding NaCl to the reaction solution,the alignment of the nanorod could be lowered.The addition of sodium halides salt significantly increases the ionic strength of the growth solution.The nanorod would be difficult to be assemble,which was conducive to the growth of nanorod.This gives access to the immobilization of TiO2 and their optical limiting applications.