反应物体积分数和pH值对水热合成二氧化钛微粒的影响

Effects of the Teactant Concentration and the pH of the System on Titanium Dioxide Particles by Hydrothermal Synthesis

采用水热合成工艺,以钛酸丁酯(Ti(OC4H9)4)为前驱体,通过改变反应物的体积分数和体系的pH值,合成了不同晶型和形貌的二氧化钛(TiO2)微粒.同时,使用X射线衍射仪(XRD)和扫描电子显微镜(SEM)对此产物进行了表征.结果表明:反应物的体积分数和pH值对TiO2微粒的晶型、形貌和晶粒尺寸均有较大的影响.当Ti(OC4H9)4体积分数较大时,出现锐钛矿型晶体,但结晶不完善,微粒较大,且有团聚现象;Ti(OC4H9)4体积分数较小时,出现金红石型晶体,微粒相对较小,随着反应物体积分数的减小微粒的晶型由锐钛矿型转为金红石型,晶粒尺寸逐渐增大.在酸性溶液中,有利于形成金红石型微粒,而在碱性溶液中,有利于形成锐钛矿型微粒,随着体系的pH值增加,晶粒尺寸也逐渐增大.

Different size and morphology of titanium dioxide particles were hydrothermally prepared by using tetrabutyl titanate as precursor and characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The results show that the concentration of the reactant and the pH of the system have greatly influence on the crystalline phase, morphology and size of the particles. The anatase crystal appear in higher Ti（OC~ Hg）~ concentration, but the crystallization is not yet perfect, the Ti02 particles are large, and has the aggregate phenomenon occurrence. On the contrary, the rutile crystal appear when Ti （OC4 H0）4 concentration is low and the TiO2 particles are small. With the decrease of concentration, the crystal structure of TiO2 change from the anatase into the rutile and the grain size gradually increases. The acidic solution is favorable to the formation of the futile crystal, while the anatase crystal is easy to form in the alkaline solution, and the grain size also gradually increases with the increase of the pH value of the system.