【作者】 车传强；

【导师】 李蓉萍；

【作者基本信息】 内蒙古大学 ， 物理电子学， 2004， 硕士

【摘要】 小角X射线散射（SAXS）是一种用来探测从几到几百纳米尺度范围内物质结构的实验手段。物质内部该尺度范围内电子密度不均匀性是产生小角散射现象的根本原因。近年来，纳米氧化物材料及多孔材料方面的SAXS研究已引起科研工作者的极大兴趣。 采用溶胶一凝胶法制备了纳米TiO₂及掺杂纳米TiO₂，然后利用SAXS方法以及DTA和XRD方法对体系进行了研究，对其尺寸、微观结构进行了表征，研究了这些性质之间的关系。将分形概念和SAXS中其他表征物质结构的参数有机结合，研究了散射体的相变行为；将Porod定律和与传感性能有关的比表面有机的联系了起来。类似工作所查文献中未见报道。 分析表明热处理温度是导致纳米TiO₂长大的主要原因，在相变温度附近，晶体迅速地长大，相变后增长速度下降，而无论是否掺杂。加入少量的NB₂O₅或一定量的稀土元素Ce，可以改变纳米TiO₂的相变温度，并能影响晶粒的增长。 SAXS研究表明所有锐钛矿相纳米TiO₂体系满足Porod定律；锐钛矿相纳米TiO₂体系没有分形结构的现象；无定形的TiO₂纳米颗粒及相变温度以上热处理的体系均对Porod定律呈正偏离。更多还原

【Abstract】 Small-angle X-ray scattering (SAXS) is the technique of choice for probing structure features that occur on length scales between approximately Inm and 100nm. The only requirement for SAXS is the presence of inhomogeneities in electron density. There is an increasing interest on the SAXS study of the oxide nanoparticles and porous materials in recent years.The pure nano-TiO2 and doped-TiO2 are prepared by sol-gel process. The samples were investigated by synchrotron Small-Angle X-Ray Scattering, DTA and XRD. The size and microstructure were characterized. The phase transition behavior of sample was analyzed by using SAXS fractal theory. The relationship between Porod’s law and specific surface was found first time. The average particle size increased with the annealing temperature increasing. When the temperature increased high enough, the anatase changed into rutile. A little Nb2O5or cerium doped into sample can change phase-transition temperature and influence the growth of particle. SAXS indicates that all anatase follow Porod’s law but not show any fractal structure. Other samples gave a positive deviation from Porod’s law.更多还原