TiO_2超细微粒的有序组装

ORDER-ASSEMBLY OF TiO_2 ULTRAFINE PARTICLES

将水解法制备的ＴｉＯ＿２超细微粒溶胶液滴于水平放置的高取向热解石墨（ＨＯＰＧ）基底上，可形成一定面积的有序性排列较好的二维结构。基底ＨＯＰＧ具有原子级粗糙度表面。沿液膜铺展方向取点进行原子力显微镜观察，证实在扩展液膜边缘的ＴｉＯ＿２超细微粒有序性最好，而且粒径最小；靠近落滴位置处，粒子多聚集成一定的畴结构，粒子的粒径也增大。此外，对比观察了落滴于水平云母基底上形成膜的表面形貌，进行了相应的讨论。

The morphology of TiO_2 thin films has been observed by means of an atomicforce microscope(AFM).This kind of uItrafine particles(UFP)film was pre-pared with TiO_2 sol liguid filmsspreading and thinning on a horizontal substratewhich is made of high orientation pyrolytic graphite(HOPG).Surface roughnessof the substrate is at atomic level.The observational results on several points se-lected along the direction of colloidal dispersion reveal that good quality of thetwo-dimensional(2D)nanometer-sized TiO_2 UFP array has been formed on thespreading edge. The average diameters of TiO_2 UFP are increasing with AFMscanning from the spreading edge to the central part of the liquid layer containingthe particles. A universal phenomenon of stratified and domain structures leftover by the process of the liquid films thinning in a stepwise fashion. Somemenisci formed around or between the particles could be found. It turns out thatthe main factors governing the ordering are the attractive capillary forces and theconvective transport of UFP toward this region.