水热条件对板钛矿相二氧化钛微结构的影响

Effect of Hydrothermal Conditions on the Microstructure of Brookite Titanium Dioxide

以四氯化钛和氢氧化钠为原料制备TiO2前驱体,通过水热法合成了不同形貌板钛矿相TiO2,利用X射线衍射和透射电镜对所得样品进行了表征。研究了反应初始pH值、水热反应温度和水热反应时间对TiO2形貌、物相和晶粒尺寸的影响。结果表明,pHinitial是决定TiO2粉体物相、粒径和形貌的主要因素。随着水热反应温度的升高和水热反应时间的延长,板钛矿相TiO2的晶粒逐渐长大。pHinitial的增大,导致无定形TiO2转化成板钛矿相所需的水热温度升高,水热时间变长;同时,所形成板钛矿相TiO2的晶粒尺寸和颗粒粒径也较大。XRD和TEM结果表明,板钛矿相TiO2颗粒是由多个纳米微晶组成的聚集体。当pHinitial为9.00-12.00时,200℃下水热反应24h合成了纯板钛矿相TiO2。

The brookite TiO2 with different morphologies was prepared by hydrothermal method using TiCl4 and NaOH as the starting material. The prepared samples were characterized by XRD and TEM. The effects of pHinitial value, hydrothermal temperature and hydrothermal time on the morphology, crystal phase and crystallite size of TiO2 powder were investigated. The results showed that pHinitial value was the key factor in determining the crystal phase, particle size and morphology of TiO2 powder. With the increase in hydrothermal temperature and hy- drothermal time, the crystallite size of brookite TiO2 increased accordingly. The increase of pHinitial value resulted in the rise of hydrothermal temperature and the increase of hydrothermal time needed in the transformation of amorphous TiO2 to brookite phase, at the same time, the crystallite size and particle size became larger. XRD and TEM revealed that the particles of brookite TiO2 were composite particles assembled or combined by nanocrys- talline. When pHinitial=9.00-12.00, the brookite TiO2 with single phase was obtained at 200 ℃ for 24 h.