磁性奈米線製備及其特性分析

Synthesis and Characterization of Magnetic Nanowires

辛嘉芬(Chia-Fen Hsin)

指導教授 ： 劉如熹

國立臺灣大學/理學院/化學研究所/碩士(2007年)

https://doi.org/10.6342/NTU.2007.01453

摘要

本研究第一部分證實經由電化學沈積可將鈷-鉑合金奈米線製備於多孔性鋁膜版中，且藉高溫還原過程其奈米線結構從散亂合金轉變為CoPt3(L12)穩定合金相。元素分析及晶體結構分別以能量散布X光光譜儀(EDS)與X光粉末繞射儀(XRD)鑑定，而當退火溫度達500℃時CoPt3奈米線之內部原子將形成整齊排列結構。由同步幅射X光吸收光譜(XAS)可顯示鈷鉑奈米線各階段退火溫度之原子內部電子結構與局部結構，並根據上述結果提出鈷鉑合金奈米線轉變過程之退火機制。
本研究第二部分利用陽極處理將鎳奈米線成長於陽極鋁膜模版中，且證實由此簡單方法可調節薄膜之光學特性，即金屬片表面之光學特性可藉由氧化鋁膜厚度調整，本研究將固定陽極時間以電流密度控制鋁膜厚度。穿透式電子顯微鏡(TEM)剖面影像顯示鎳奈米線成長於多孔性氧化鋁膜底部，而由於入射光與反射光之間所產生之干涉使得氧化鋁表面展現多重變化之顏色，故此一技術將可放大應用於製備金屬/氧化物奈米結構。

關鍵字

磁性奈米線 ； 鈷鉑合金 ； X光吸收光譜

並列摘要

In first part of thesis, we successfully demonstrated synthesis of Co-Pt alloy nanowire via electrochemical deposition in porous alumina templates. The Co-Pt alloy nanowires were converted from chemical disorder structure to CoPt3 (L12) through reduction process followed by alloy formation at high temperature. The elemental analysis and crystal structure analysis were carried out using energy-dispersive and X-ray diffraction method, respectively. The chemical order structure of CoPt3 nanowires was formed above annealing temperature of 500˚C. X-ray absorption spectroscopy revealed valuable information about the electronic structure and local structures at each stage. According to above results, we propose an annealing mechanism for the transformation process of CoPt nanowires.
In second part, we demonstrate a simple method to tune the optical properties of thin films of nickel nanowires grown inside an anodic alumina oxide (AAO) template by manipulating anodizing conditions. The optical properties of the metal plate can be effectively tuned by adjusting the thickness of porous alumina oxide. Under the present experimental conditions, we found that the thickness of the porous alumina oxide depends strongly on the current density because the duration of anodization was maintained constant. The transmission electron microscopic image of the cross section reveals the growth of nickel nanowires which were embedded in porous alumina oxide. Due to the interference between incident light and reflected light, the anodic alumina oxide plate exhibits a variety of color. This demonstration of tuning of optical behavior makes its usefulness in technological application possible by scaling up of the preparation of metal/oxide nanostructures exhibiting color tuning in the visible region.

並列關鍵字

Magnetic nanowires ； CoPt alloy ； X-ray absorption spectroscopy

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