氧化對鉛奈米顆粒自發磁性之影響; The spontaneous magnetism of Pb nanoparticles by oxidation

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题名:	氧化對鉛奈米顆粒自發磁性之影響;The spontaneous magnetism of Pb nanoparticles by oxidation
作者:	黃俊瑋;Chun-Wei Huang
贡献者:	物理研究所
关键词:	自旋極化;自發磁性;奈米顆粒;鉛;spontaneous;nanoparticles;spin polarization;Pb
日期:	2010-07-16
上传时间:	2010-12-08 14:23:22 (UTC+8)
出版者:	國立中央大學
摘要:	使用熱蒸鍍法製作鉛奈米顆粒，以Pb090908表示。並利用共同體積函數擬合X光繞射圖判定粒徑為24 nm，使用GSAS分析X光繞圖，確定樣品成份皆為鉛，無氧化物或者其他元素。藉由物理特性量測系統對尚未氧化樣品進行一系列不同溫度的M-H量測，量測結果發現鉛奈米顆粒在外加磁場下有自旋極化與反磁效應的現象，並使用朗之萬函數加反磁線性項擬合之來描述其磁性。本論文更對樣品進行不同程度的氧化使其在表面產生氧化物，在M-H實驗量測發現在外加磁場為零時樣品具有自發磁性，並且隨著溫度增高以及氧化物生成量增加而導致其自發磁性也會跟著增強。並藉由擬合實驗數據發現顆粒磁矩μp在起初只有Pb與PbO成份時，會隨著PbO增厚而增加；但當有Pb3O4成份生成時，顆粒磁矩μp會達到極值而開始減弱。另外，也觀察到在只有Pb與PbO成份時，飽和磁化強度隨著PbO增厚而減弱，在有Pb3O4成份出現時，飽和磁化強度則會隨Pb3O4增厚而增強。在本文中探討鉛奈米顆粒在不同的氧化過程所生成的核殼結構對顆粒自發磁性的影響。 Pb nanoparticles were fabricated by the thermal evaporation method. X-ray diffraction patterns were performed to examine particle size and composition. X-ray diffraction patterns showed that the mean particle diameters of pure Pb nanoparticles are 24 nm. No trace of oxidation or other impurity was found. The M-H curves in difference temperatures of the Pb nanoparticles can be investigated by physical property measurement system. The result of measurement was found that Pb nanoparticles had spin polarization and diamagnetic. The M-H curves of the Pb nanoparticles can be described by the Langevin function plus the diamagnetic term. A series of oxidation dependent experiments produce the oxide compound on surface of the samples. We found that spontaneous magnetism in zero magnetic field. With the increasement of temperature and oxidation, the spontaneous magnetism was enhancement. At first, the ingredients of Pb/PbO that magnetic moment μp would be increased with the thickness of PbO is thickening; when the ingredients of Pb3O4 was appearance, the magnetic moment μp would be weakened. The saturation magnetization Ms in Pb/PbO would be weakened with the PbO is thickening. The saturation magnetization Ms in Pb/PbO/Pb3O4 would be opposite. A series of oxidation dependent on experiments reveal the influence of oxidation on spontaneous magnetism in core shell of Pb nanoparticles.
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