模板法制备一维铁氧体纳米线（管）及其磁性能研究

发布时间：2018-04-26 08:35

本文选题：多孔氧化铝膜 + 纳米线(管)阵列　；参考：《沈阳理工大学》2010年硕士论文

【摘要】： 本论文采用阳极氧化法制备了多孔氧化铝膜(AAO),再以所制备的AAO为模板,运用溶胶/凝胶法制备了钴铁氧体纳米线/管和钡铁氧体纳米线。经XRD、SEM、VSM等表征手段,研究了AAO的制备影响因素、铁氧体纳米线/管的制备影响因素及磁性能。 AAO制备影响因素研究结果表明:电压对AAO纳米孔道影响显著,升高氧化电压引起孔径增大且孔排列有序程度增加,但电压过高会因氧化反应过于激烈而不利于纳米孔道的形成;二次阳极氧化较一次阳极氧化所得到的孔的空隙率提高,孔间距减小,且孔更接近正六边形;在一定浓度范围内,草酸电解液浓度对阳极氧化过程无明显影响;适当提高扩孔温度和延长扩孔时间能增大孔径;随着氧化时间延长,膜厚度呈现“先迅速增长、再缓慢增加、然后平稳”的变化趋势;氧化温度较高易引起酸性电解液对孔洞和阻挡层的腐蚀作用加剧,不利于AAO的制备。钴铁氧体纳米线/管制备影响因素研究结果表明:沉积时间和沉积次数影响铁氧体前驱体在AAO孔道中的填充程度,进而影响纳米线长度或线状、管状形貌的形成;溶胶pH值的减小会引起AAO腐蚀,因而要制备更长的纳米线需提高溶胶pH值;延长煅烧时间引起钴铁氧体纳米线结晶有序程度提高;升高煅烧温度不但使钴铁氧体纳米线的结晶有序程度显著提高,且部分Al~(3+)取代了Fe~(3+),进而使得钴铁氧体晶胞参数减小。钴铁氧体纳米线/管磁性能研究结果表明:纳米线长径比的提高有利于钴铁氧体纳米线的饱和磁化强度M_s、剩余磁化强度M_r、矫顽力H_c、矩形比P的增加;直径相近条件下,钴铁氧体纳米管的磁性能优于纳米线;煅烧时间和煅烧温度对钴铁氧体纳米线的M_s、M_r、H_c和P也存在明显影响。延长煅烧时间引起M_s、M_r、H_c和P均有所增加,升高煅烧温度则使M_s、M_r、H_c和P均显著增加。这主要归因于延长煅烧时间或提高煅烧温度导致钴铁氧体纳米线的结晶度提高或显著提高,且增加煅烧温度使部分Fe~(3+)被Al~(3+)取代,进而提高了铁氧体纳米线的磁性能。前述结果暗示,当磁晶各向异性固定于一定程度时,形状各向异性对钴铁氧体磁性能的影响不容忽视;再者,基于钴铁氧体纳米线的磁性能与其长径比、线或管状形貌及结晶有序程度的内在联系,可通过制备条件对钴铁氧体纳米线的长径比、线或管状形貌或结晶有序程度的影响,实现对钴铁氧体纳米线磁性能的控制。
[Abstract]:In this paper, the porous alumina membrane (AAO) was prepared by anodic oxidation, and the prepared AAO was used as a template. The nanowire / tube and barium ferrite nanowires were prepared by the sol / gel method. The influencing factors of preparation of AAO, the influencing factors and magnetic properties of the preparation of ferrite nanowires / tubes were studied by means of XRD, SEM and VSM.
The influence factors of the AAO preparation show that the voltage has a significant effect on the nano channel of AAO, the increase of the oxidation voltage and the increase in the order of the pore arrangement, but the excessive voltage will not help the formation of the nanoscale through the excessive oxidation reaction, and the porosity of the hole obtained by the two anodization is higher than that of the first anodic oxidation. In a certain concentration range, the concentration of oxalic acid has no obvious effect on the anodic oxidation process, and the pore size can be increased by increasing the reaming temperature and prolonging the reaming time. With the prolonged oxidation time, the film thickness presents a "first rapid growth, then slow increase, and then smooth" change trend. The higher temperature causes the corrosion of acidic electrolyte to the pores and barrier layers, which is not conducive to the preparation of AAO.
The study results of cobalt ferrite nanowires / control factors show that deposition time and deposition times affect the filling degree of ferrite precursor in the AAO channel, and then influence the length or line shape of nanowires and the formation of tubular morphology; the decrease of the sol pH value will cause AAO corrosion, because the preparation of longer nanowires needs to increase the sol pH value; The crystallization order of cobalt ferrite nanowires is increased by long calcining time, and the increase of calcining temperature not only improves the crystallization order of the cobalt ferrite nanowires, but also the partial Al~ (3+) is replaced by Fe~ (3+), which makes the co ferrite crystal cell parameters decrease.
The study results of cobalt ferrite nanowires / magnetic properties show that the increase of the length to diameter ratio of nanowire is beneficial to the saturation magnetization of cobalt ferrite nanowires M_s, the residual magnetization M_r, coercive force H_c, and the increase of the rectangular ratio P; the magnetic properties of cobalt ferrite nanotubes are better than the nanowires under the same diameter; calcining time and calcining temperature have a good effect on cobalt iron. The M_s, M_r, H_c and P of the oxygen nanowires also have obvious influence. The prolongation of calcining time increases M_s, M_r, H_c and P. The increase of calcination temperature makes M_s, M_r, H_c and P significantly increase. This is mainly attributed to the prolongation of calcining time or the increase of calcining temperature to increase or significantly increase the crystallinity of cobalt ferrite nanowires, and increase calcination. The temperature makes some Fe~ (3+) replaced by Al~ (3+), and then increases the magnetic properties of the ferrite nanowires. The results suggest that the influence of the shape anisotropy on the magnetic properties of cobalt ferrite can not be ignored when the magnetocrystalline anisotropy is fixed to a certain extent; moreover, the magnetic properties of the cobalt ferrite nanowires are compared with the length to diameter ratio, line or tubular morphology and the shape of the magnetic properties of the cobalt ferrite nanowires. The intrinsic relationship between the degree of crystallization and the degree of crystallization can be used to control the magnetic properties of cobalt ferrite nanowires by the influence of the preparation conditions on the length to diameter ratio, line or tubular morphology or the degree of crystal order of the cobalt ferrite nanowires.

【学位授予单位】：沈阳理工大学
【学位级别】：硕士
【学位授予年份】：2010
【分类号】：TB383.1

【参考文献】