化学气相沉积法制备金属铁磁性纳米线及其性能研究

发布时间：2018-04-28 11:13

本文选题：化学气相沉积法 + 纳米线　；参考：《浙江工业大学》2015年硕士论文

【摘要】：金属磁性纳米线具有的诸多独特的物理化学特性主要来源于其特殊的显微组织结构,而显微组织结构取决于纳米线的制备工艺。在众多纳米线的制备方法中,化学气相沉积法(CVD)是一类可大量获取纳米线,并已部分实现商业化应用的制备工艺。然而,由于金属材料极高的气化温度,因此,CVD法常被用于制备各类氧化物或半导体纳米线。然而CVD法制备金属磁性纳米线未见有研究报道。故本文拟以具有低气化温度的二茂铁为原材料,采用纳米金颗粒作为催化剂,通过CVD法制备铁磁性纳米线。首先,作为纳米线的前驱体必须具备下述条件:较低的气化温度;分解温度适当高于气化温度;气化温度与分解温度相接近。通过TG分析测试表明二茂铁的具有较低的气化温度且分解温度大于气化温度,本文选取二茂铁(FeC10H10)作为前驱体,并采用粒径纳米金颗粒作为催化剂。沉积温度被设定为500°C,550°C,600°C,650°C,700°C,750°C;沉积时间设定为1h,1.5h,2h,2.5h;载体流速设定为25sccm,50sccm,70sccm,100sccm;沉积模板选择蓝宝石和硅片。文章研究了制备工艺参数对纳米线的组织形貌的影响,通过优化工艺参数,在沉积温度为600°C,沉积时间为2h,载体流速为70sccm的条件下,在蓝宝石基板上获得大量的直径和长度分别在125nm和2um左右的纳米线,并通过XRD,SEM,TEM等手段确定了所获得的纳米线为单晶铁纳米线。其次,本文进一步探讨了金属纳米线的生长机制,揭示了其生长过程可分为四个阶段:1.固态二茂铁气化,气态二茂铁跟随载体输送到沉积室中,在沉积室中发生分解反应,在600°C下,二茂铁分解为Fe和双戊二烯;2.分解的Fe原子被模板上的Au纳米吸附,形成Fe-Au合金;3.Fe-Au合金作为结核点进一步吸附大量的Fe原子;4.单晶Fe纳米线以结核点为晶核定向生长从而形成纳米线。通过TEM、EDS检测可以说明,单晶Fe纳米线的生长机理是气-固(Vapor-Solid)生长机理。最后,本文采用振动样品磁强计(VSM)沿平行和垂直纳米线轴向方向分别测试了纳米线的磁滞回线。测试结果表明:平行于纳米线轴向方向为易磁化方向,然而两个方向的各向异性能相差不显著,其原因在于纳米线的各向异性主要由形状各向异性和磁晶各向异性决定,而两者存在相互竞争关系,且本文制备的纳米线中形状各向异性Ed=1.8×104 J/m3要略微大于磁晶各向异性Ea=1.2×104 J/m3,从而表现出上述低的剩磁比为0.37。
[Abstract]:Many unique physical and chemical properties of metallic magnetic nanowires are mainly derived from their special microstructure, and the microstructure depends on the preparation process of nanowires. Among the many preparation methods of nanowires, chemical vapor deposition (CVD) is a kind of preparation process which can obtain nanowires in large quantities and has been partially commercialized. However, due to the extremely high gasification temperature of metal materials, chemical vapor deposition (CVD) is often used to prepare various oxide or semiconductor nanowires. However, the preparation of metal magnetic nanowires by CVD method has not been reported. Therefore, ferrocene with low gasification temperature was used as raw material and gold nanoparticles were used as catalyst to prepare ferromagnetic nanowires by CVD method. First of all, the precursor of nanowires must have the following conditions: lower gasification temperature, higher decomposition temperature than gasification temperature, and close gasification temperature to decomposition temperature. TG analysis shows that ferrocene has a lower gasification temperature and decomposition temperature is higher than the gasification temperature. In this paper, ferrocene ferrocene (FeC10H10) is chosen as the precursor, and the particle size of gold nanoparticles is used as the catalyst. The deposition temperature was set to 500 掳C, 550 掳C, 600 掳C, 600 掳C, and 650 掳C, 700 掳C, 700 掳C, 750 掳C, the deposition time was 1 h, 1.5 h and 2 h, the carrier velocity was set at 25 sccm, 50 sccm, 70 sccm, 100 sccm, and sapphire and silicon wafer were selected for the deposition template. The effect of preparation process parameters on the morphology of nanowires was studied. By optimizing the process parameters, the deposition temperature was 600 掳C, the deposition time was 2 h, and the carrier flow rate was 70sccm. A large number of nanowires with diameters and lengths of about 125nm and 2um were obtained on sapphire substrates. The nanowires were determined to be single crystal iron nanowires by means of XRD-SEMT-TEM. Secondly, the growth mechanism of metal nanowires is further discussed, and the growth process can be divided into four stages: 1: 1. In solid ferrocene gasification, gaseous ferrocene was transported to the deposition chamber with the carrier, and decomposition reaction occurred in the deposition chamber. At 600 掳C, ferrocene was decomposed into Fe and dipentadiene 2. The decomposed Fe atoms were adsorbed by au nanoparticles on the template to form Fe-Au alloy 3.Fe-Au alloy as the nodule point for further adsorption of a large number of Fe atoms. Monocrystalline Fe nanowires form nanowires by directional growth with nodule as nucleus. The growth mechanism of single crystal Fe nanowires is gas-solid Vapor-Solid- solid. Finally, the hysteresis loops of the nanowires were measured by vibrating sample magnetometer (VSM) along the axial direction of parallel and vertical nanowires, respectively. The results show that the anisotropy energy of nanowires is easy to be magnetized parallel to the axial direction of nanowires, but the anisotropy energy of the two directions is not significant. The reason is that the anisotropy of nanowires is mainly determined by shape anisotropy and magnetocrystalline anisotropy. Moreover, the shape anisotropic Ed=1.8 脳 10 ~ 4 J/m3 in the nanowires is slightly larger than the magnetocrystalline anisotropy Ea=1.2 脳 10 ~ 4 J / m ~ (3), which shows that the low remanence ratio is 0.37.
【学位授予单位】：浙江工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.1

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