单分散性Fe_3O_4/CoO/SiO_2复合纳米粒子的制备与表征

采用溶剂热法,在160℃下,以聚乙烯吡咯烷酮(PVP)为表面活性剂,制备Fe3O4/CoO复合纳米粒子;然后采用St觟ber法,在35℃下,以氨水催化正硅酸乙酯(TEOS),制备Fe3O4/CoO/SiO2复合纳米粒子。考察反应物配比、氨水浓度、醇水比对Fe3O4/CoO/SiO2复合粒子磁学性能的影响。对复合纳米粒子采用X射线衍射(XRD)、透射电子显微镜(TEM)、交流梯度磁强计(VSM)、差热分析(DTA)等手段进行表征分析。结果表明:Fe3O4/CoO/SiO2复合纳米粒子晶形生长良好,粒径在20nm左右。利用CoO进行表面修饰后,提高了纳米Fe3O4粒子的饱和磁化强度,通过包覆SiO2进行表面改性后,提高了纳米Fe3O4粒子的分散性和稳定性。实验确定了Fe3O4/CoO复合粒子与TEOS的摩尔比1∶2、TEOS与氨水的摩尔比1∶3、无水乙醇与蒸馏水的体积比2∶1为最佳反应物配比。

SYNTHESIS AND CHARACTERIZATION OF MONODISPERSE Fe3O4/CoO/SiO2 CORE/SHELL NANOPARTICLES

Fe3O4/CoOCore/shell type nanoparticles were synthesized by a solvethermal method with the surfactant（PVP） at 160℃,then Fe3O4/CoO/SiO2 composite nanoparticles are prepared by a Stber method in which ammonia is a catalyst.We also studied the influencing factors of the reaction such as mixture ratios,ammonia concentration,and alcohol-water ratio.The particles were characterized by using various experimental techniques such as transmission electron microscopy（TEM）,X-ray diffraction（XRD）,Alternating gradient force magnetometer（AGM） and Differential thermal analyzer（DTA）.The grain size of Fe3O4 /CoO/SiO2 nanoparticles is about 20nm in diameter.The surface modification with CoO in nano-Fe3O4 particles increases the saturation magnetization,and Further surface modification with SiO2 can improve the dispersion and stability of nanoparticles.The best ratio of reactants in the materials reaction is following：the molar ratio of Fe3O4 /CoO with TEOS composite particles is 1：2,the amount of ammonia is 3ml,the volume ratio of ethanol with distilled water is 2：1.