微波水热合成法制备TiO_2纳米管的晶型和形貌研究

Influence of microwave treatment on crystal form and morphology of TiO_2 nanotube by hydrothermal synthesis

采用溶胶-凝胶法合成TiO2纳米粉,并分别在500、600和700℃进行煅烧。并以此为前驱物,采用微波水热合成法制备TiO2纳米管。用X射线衍射(XRD)、场发射扫描电镜(FESEM)和场发射透射电镜(FETEM)分别对TiO2纳米粉和纳米管进行表征。结果显示,煅烧温度影响TiO2纳米粉晶粒尺寸,微波水热合成法对TiO2纳米管的晶型和结晶度的影响明显。同时研究TiO2纳米管的晶型和结晶度的变化机制,结果表明,以600和700℃煅烧的TiO2纳米粉为前驱物经微波水热合成法合成的TiO2纳米管中部分热力学亚稳态的锐钛矿向稳定态的金红石进行转变。

TiO2nanopowders were synthesized by sol-gel method and calcined at 500℃,600℃and 700℃respectively.With the microwave-assisted hydrothermal synthesis method,the TiO2 nanotubes were successfully prepared using TiO2 nanopowders as the precursors.The crystalline structure of TiO2 nanotubes and nanopowders were characterized by X-ray diffraction（XRD）,field emission scanning electron microscope（FESEM）and the field emission transmission electron microscopy（FETEM）.The results showed that the calcined temperature affected the crystallite size of TiO2 nanopowders,and the processing of microwave-assisted hydrothermal synthesis had significantly effect on the crystallinity and crystal form of TiO2 nanotube.The mechanisms of the changes on crystal form and crystallinity had been discused.Partial thermodynamically metastable anatase was transformed to the most stable form of rutile phase in the TiO2 nanotubes,which was made by microwave-assisted hydrothermal synthesis using the TiO2 nanopowders with 600℃ calcined as the precursors.