摘要
采用化学络合溶胶-凝胶法，结合自蔓燃合成工艺制备了结构可控、分散性良好的 TiO_2纳米粉体．考察了原料组成、凝胶膨胀程度和温度机制对粉体结构、分散性的影响，用漫反射光谱测试了所制备粉体的光吸收性能，结果表明，将原料中氧化剂与还原剂的摩尔比从2增加到7，在600℃的煅烧温度下可以得到金红石含量在25%～68.2%之间的 TiO_2，这些结构不同的粉体粒度为30nm 左右；凝胶前驱体经过150℃充分膨胀炭化，能有效阻止胶粒间氢键的形成，并且能够防止因毛细管作用而导致的凝胶网络坍塌，从而得到单分散无团聚粉体：提高煅烧温度，金红石含量增多、颗粒粒度增大，800℃时出现团聚体；用该工艺制备的粉体的光吸收范围发生明显红移，与市售金红石型 TiO_2相比，反光率下降10%以上；金红石含量为55.5%的混晶型粉体显示出最好的光吸收性能。
Highly dispersed TiO2 nanometer powders with controlled structure were synthesized by chemical complex sol-gel auto-igniting process. The initial oxidant/reductant molar ratio, swelling of gel and temperature schedule were chosen as key variables for the controlled synthesis: by changing the initial oxidant/ reductant molar ratio from 2 to 7, TiO2 having a particle size about 30 nm was obtained at 600 degreesC with a mass fraction of rutile ranging from 25% to 68.2%; sufficient swelling and carbonizing of the gels at 150 degreesC removed non-bridging hydroxyl groups and broke down the hydrogen bonds between particles, so the formation of hard agglomerates was avoided; the mass fraction of rutile and particle size of TiO2 increased with increasing of calcination temperature; agglomerates of TiO2 Were formed at 800 degreesC. The optical absorption edges significantly shifted to longer wavelengths in the UV-Vis diffuse reflectance spectra of the as-prepared TiO2, and the reflectivity was about 10% lower than that of commercial TiO2. It was found that the as-prepared TiO2 with the optimal rutile fraction of 55.5% achieved the best optical absorption.
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
2005年第1期57-62,共6页
Acta Physico-Chimica Sinica
关键词
Sol—gel自蔓燃
二氧化钛
纳米粉体
控制合成
sol-gel auto-igniting process
titanium dioxide
nanometer powder
controlled synthesis
