纳米二氧化钛颗粒的超临界水热合成

摘要

利用四氯化钛溶液通过超临界水热合成法制备了纳米二氧化钛颗粒,采用X射线衍射(XRD),透射式电子显微镜(TEM)等手段表征了产物的大小、结晶度及形貌.研究了初始反应物浓度、初始溶液pH值对二氧化钛颗粒的大小、结晶度和形貌的影响,并对影响机理进行了讨论.结果表明:在所有的试验中均获得了纳米级的二氧化钛颗粒;在反应温度400℃、压力30 MPa、反应时间5 rmin、初始四氯化钛溶液浓度为0.05 mol/L的超临界水热合成条件下,合成了平均颗粒粒径为20 nm左右且结晶良好的二氧化钛颗粒,颗粒成椭球形或四边形;当四氯化钛溶液浓度由0.05 mol/L增加到0.1 mol/L,合成的二氧化钛颗粒尺寸变大,且椭球形颗粒数量减小,棒状的颗粒增加;当钛离子和氢氧根离子的浓度比[Ti4+]/[OH-]由1∶0变为1∶3,即pH值增加时,颗粒的粒径减小,颗粒的结晶度下降.%Titania nanoparticles are prepared by supercritical hydrothermal synthesis technology using TiCl4 solution as precursor.The particle size,morphology and crystallinity of the particles are characterized by XRD and TEM.The effects of initial concentration of reactants and pH on the particle size,morphology and crystallinity of the particles are studied and the effect mechanism is investigated.The present results indicate that nano-sized TiO2 are obtained in all the researched parameter ranges.Ellipsoid or quadrangle TiO2 nanoparticles with average size of 20 nm and high crystallinty degree are obtained under the reaction temperature of 200 ℃,reaction pressure of 30 MPa,and reaction time of 5 min.The experimental results show that the number of rob-shaped particles increases and the average particle size increases as the concentration of Ti4 + increases from 0.05 mol/L to 0.1 mol/L.When the concentration ratio of titanium ion and hydroxide changes from 1 ∶ 0 to 1 ∶3,the particle size decreases and the crystallinty degree becomes lower.