| 准一维铁的氧化物有序阵列的制备与性质 |
| Alternative Title | fabrication and study of quasi-one-dimensional iron oxides ordered arrays
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| 张丽英 |
| Thesis Advisor | 薛德胜
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| 2005-05-31
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| Degree Grantor | 兰州大学
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| Place of Conferral | 兰州
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| Degree Name | 博士
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| Keyword | 铁的氧化物
纳米线阵列
磁性
穆斯堡尔效应
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| Abstract | "近年来，准一维纳米材料由于在电学、光学、磁学、力学和热学方面展现出优异的特性，从而在纳米器件、传感器、激光器等方面具有应用前景而倍受关注。准一维磁性纳米有序阵列是实现超高密度垂直磁记录比较理想的纳米结构，目前，许多金属和合金等磁性纳米线阵列已经被合成，然而，作为重要磁记录材料的铁氧体其准一维结构却很少研究。本论文的主要工作是通过在AAO模板中先沉积b-FeOOH纳米线阵列，再对其进行热处理的方法合成铁的氧化物纳米线阵列，并研究了这些纳米线阵列的性质。主要内容和创新点如下：
一、首次制备了不同直径的b-FeOOH纳米线阵列，研究了纳米线阵列的热稳定性和磁性。发现奈尔温度远小于块体材料；在低温下出现自旋“冻结”现象，而且ZFC曲线的最大值随直径和外加磁场变化。这些反常磁性主要与纳米线的非晶结构有关。
二、制备了不同直径的a-Fe2O3纳米线阵列，首次用低温穆斯堡尔谱研究了纳米线阵列的Morin相变，并估算了超顺磁阻截温度、德拜温度和磁晶各向异性常数。同时发现纳米线阵列的穆斯堡尔效应具有明显的尺寸效应。
三、首次制备了不同直径和长短的Fe3O4纳米线阵列，找出了适合超高密度磁记录即具有垂直磁各向异性的纳米线阵列；研究了纳米线阵列的Verwey相变及其尺寸效应；低温下纳米线阵列出现自旋“冻结”现象，ZFC曲线的最大值随直径和外加磁场变化；研究了纳米线阵列中的微观磁结构，并用微磁学方法模拟了磁矩的静态分布。
四、首次制备了不同直径的g-Fe2O3纳米线阵列；研究了纳米线阵列的微观磁结构，估计了磁矩取向、阻截温度和磁晶各向异性常数；研究了室温磁性及其尺寸效应。
" |
| Other Abstract | "In recent years, quasi-one-dimensional nanomaterials have been attracted much attention due to their superior electrical, optical, magnetic, mechanical and thermal properties, as well as their potential applications in nanodevices, sensors, and lasers. Quasi-one-dimensional magnetic ordered arrays have been considered promising candidates for high-density perpendicular magnetic recording, and the electrodeposition based on anodic aluminum oxide (AAO) template is a main method to prepare these nanoarrays. So far, a lot of metal and alloy nanowire arrays have been successfully prepared. However, as a very important class of magnetic recording material, there is little report on quasi-one-dimensional ferrite nanomaterials. This paper is aim to fabricate iron oxides nanowire arrays by electrodepositing b-FeOOH nanowires in AAO templates, followed by a heat-treating process. The properties of these nanowire arrays have also been studied. Some main contents and innovations in this paper are listed in the following:
I. Different diameters of b-FeOOH nanowires have been fabricated for the first time. Their thermal stability and magnetic properties have been studied. The Neel temperatures of these nanowire arrays are much lower than that of bulk materials. At low temperature a “spin-freezing” has been observed in ZFC curves, and the temperature corresponding to the maximum value of ZFC curves increases (decreases) with increasing diameter (increasing applied fields). These abnormal magnetic properties are associated with their amorphous structures.
II. Different diameters of a-Fe2O3 nanowires have been fabricated. Low temperature Mössbauer spectra were firstly used to investigate the Morin transition. The Blocking temperature, Debye temperature and the magnetic anisotropy constant were also evaluated. In addition, size effect on Mössbauer effect was also investigated.
III. For the first time, different diameters and lengths of Fe3O4 nanowires have been fabricated. The perpendicular magnetic anisotropy which is suitable for high-density magnetic recording has been found. The Verwey transition and its size effect of these nanowire arrays were also studied. At low temperature, the “spin-freezing” was observed, and the temperature corresponding to the maximum value of ZFC curves varies with diameter and the applied field. In addition, the orientation of the magnetic moments was also studied and the static distribution of the magnetic moment was s... |
| URL | 查看原文
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| Language | 中文
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| Document Type | 学位论文
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| Identifier | https://ir.lzu.edu.cn/handle/262010/228996
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| Collection | 物理科学与技术学院
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Recommended Citation
GB/T 7714 |
张丽英. 准一维铁的氧化物有序阵列的制备与性质[D]. 兰州. 兰州大学,2005.
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