空心Fe_3O_4纳米微球的制备及生长机制分析

Preparation and Growth Mechanism of Hollow Fe_3O_4 Nano-microspheres

采用控制变量法,探讨了水热法合成Fe_3O_4时,不同实验参数对其形貌、尺寸、分散性的影响。用x射线衍射仪(XRD)、扫描电子显微镜(SEM)对样品的结构和形貌进行表征,并分析Fe3O4纳米微球的生长机制。实验结果表明:以FeCl_3?6H_2O 0.27 g、柠檬酸三钠0.88 g和尿素(Urea)0.36g为原料,聚丙烯酰胺(PAM)0.35 g为稳定剂,200℃下反应12 h制备得到了具有尖晶石结构的Fe3O4,形貌为疏松多孔的空心球状结构,具有粒径分布均匀、分散性良好和无毒的特点。Fe3O4纳米微球尺寸约160 nm,具有独特的分等级结构,即整个微球由粒径18 nm左右的初级晶粒自组装堆叠而成,其形成过程可以用Ostwald Ripening(OR)熟化机制进行解释,即内部晶粒的再溶解和外部晶粒的再长大,最终形成这种特殊的疏松多孔空心结构。

Using the control variable method, Spherical Fe3O4 particles with mesoporous hollow structure were synthesized by hy-drothermal method from 0.27 g of FeCl3 ？ 6H2O, 0.88 g of Sodium Citrate, 0.36g of Urea, and0.35 g of polyacrylamide （PAM） as addi？tive, the reaction temperature is 200℃ and reaction time is 12 hours. The structure and morphology of Fe3O4 nano-microspheres werecharacterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）. The achievements are as bellow： The hollow Fe3O4particles possess hierarchical structure, in which large particles （160nm） are assembled by 18nm and smaller primary Fe3O4 crystals.The formation of hierarchical hollow structure can be explained by the Ostwald ripening process. The samples are dispersed, water-sol？uble, homogeneous in particle diameter and super paramagnetic, finally, this special porous hollow structure is formed.