調控鎳奈米微粒粉末的磁化強度

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/7477

Title:	調控鎳奈米微粒粉末的磁化強度
Authors:	陳志瑋;Zhi-Wei Chen
Contributors:	物理研究所
Keywords:	鎳;奈米微粒;磁化強度;magnetization;nanoparticle;Ni
Date:	2006-06-16
Issue Date:	2009-09-22 10:58:33 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	為了觀察鎳奈米微粒間交互作用對其磁特性的影響，我們對樣品做壓合的動作，以調控微粒間的距離，而聚合密度（CD）的範圍大約從1 %到70 %。在實驗中我們觀察到了兩個現象，首先在8 nm及9 nm的鎳奈米微粒中，由樣品的飽和磁化強度（Ms）值與CD間的關係圖中，我們看到了Ms隨著CD增加而增加，到了某個CD值會開始減弱，此現象主要來自於微粒間的交互作用，而此交互作用的形式是磁偶極間交互作用。第二個現象是樣品的磁滯曲線與Langevin function的擬合曲線會有一段差異產生，此現象只在低溫下發生，而且在不同CD下皆有。我們推測這個差異發生的原因可能與微粒間交互作用、熱能量、各向異性及微粒磁矩分佈有關。 In studying the influence of interparticle interaction on the magnetic characters of Ni nanoparticle. We controled the distance among particles by means of pressing the very loosely packed nanoparticle powder samples, characterized by the compacting density (CD) of the samples that ranging from 1 % to 70 % of the density of bulk Ni. Two main phenomena were observed. First, the saturation magnetization (Ms) of the sample increases as CD is increased up to a certain CD value, it then decreasing with the further increasing of CD. This behavior mainly associated with the interparticle interactions, which may take the form of magnetic dipole-dipole interaction. Second, there are noticeable deviations between the hysteresis curve and the Langevin behavior. The deviations only were cleanly revealed at low temperatures. The interparticle interaction, thermal energy, anisotropy, and size distribution can all be responsible for the occurrence of non-Langevin behavior.
Appears in Collections:	[Graduate Institute of Physics] Electronic Thesis & Dissertation

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