近年來，氧化鐵奈米顆粒作為軟磁性材料被應用在相當多的領域當中，如生醫領域、電子工業及半導體工業中。因其在奈米尺度下具有高磁飽和、高磁導率以及相當低的矯頑力，呈現超順磁性之特性。然而受限於氧化鐵之化學組成及晶體結構，其磁性質的加強，諸如提高磁飽和、進一步降低矯頑力，都受到一定的限制。雖然在Vestal等人的研究中，有利用表面修飾強化磁性質的方法。但使用二元元素置換氧化鐵顆粒中的鐵元素以及討論反應時的酸鹼環境對磁性質之影響，卻相對稀少。因此本研究主要目的為使用共沉析法製備及分析Fe3O4, MnxFe3-xO4, ZnyFe3-yO4奈米顆粒之基本性質，與不同比例之MnxZnyFe3-x-yO4奈米顆粒的晶體結構、化學組成及磁性質等的探討。
本論文實驗結果與討論將分成三大部分，第一部分為製備Fe3O4奈米顆粒，前驅物為溶解氯化鐵及氯化亞鐵之水溶液進行共沉析合成法，透過改變前驅物二價及三價鐵離子之比例及反應環境酸鹼值控制顆粒尺寸、晶體結構及組成比例，並測試其磁性質。第二部分為單一元素置換之MnxFe3-xO4及ZnyFe3-yO4奈米顆粒，控制前驅物中錳或鋅的比例，合成出不同置換程度之氧化鐵奈米顆粒。第三部分為同時添加錳及鋅置換之MnxZnyFe3-x-yO4之合成與分析，透過不同比例之錳、鋅離子置換奈米顆粒中的二、三價鐵離子，合成出具較佳磁性質之MnxZnyFe3-x-yO4奈米顆粒。錳離子對鐵的置換降低了晶體結構中的(311)及(440)的平面距離，並使晶粒尺寸增加，使四面體格隙與八面體格隙以及八面體格隙與八面體格隙之間之超互換交互作用加強，進而提升整體的磁矩飽和。此外，透過以鋅離子取代部份八面體格隙中的鐵，造成八面體格隙間的磁偶極矩交互作之不對稱性增加，以降低反向偶極矩的作用，達成提昇磁飽和極降低矯頑力之目的。本實驗使用超導量子干涉儀分析其磁性質，電子能譜儀分析化學組成、鍵結結構，X射線繞射儀、場發掃描式電子顯微鏡與穿透式電子顯微鏡分析其晶體結構、表面形貌。

(Mn, Zn) ions were doped into Fe3O4 nanoparticles to enhance the magnetic property of MnxZnyFe3-x-yO4 nanoparticles, by adding the (Mn, Zn) ion into the precursor solution. Nanoparticles are synthesized through an easy, one-step and quick aqueous co-precipitation method. Iron(III) chloride [FeCl3⋅6H2O], manganese(II) chloride [MnCl2·4H2O], and zinc chloride [ZnCl2] were dissolved into hydrochloric acid to form the precursor solution with surfactant adding. NH4OH was then added into the precursor solution as reagent and control to a certain pH value. After vigorous agitation, precipitates were collected. To investigate the microstructure, chemical composition and magnetic properties, the obtained powders were characterized using field emission scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffractometry, Electron Spectroscopy for Chemical Analysisand and superconducting quantum interference measurement device. The effects and mechanism of Mn and Zn ion additions on the chemical composition and magnetic properties are presented and discussed.

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