本實驗由化學熱裂解法製作出二氧化鈰(CeO2)奈米粒子，摻雜元素鋁(Al)與銅(Cu)，藉由控制摻雜元素的濃度對奈米粒子的結構特性與磁性變化為研究主幹。由X光繞射(XRD)確認其製作樣品為面心立方的螢石結構，樣品中無長程有序的鋁與銅之氧化物存在，並由Scherrer equation估算製作出的晶粒大小約為8nm，經過氧氣鍛燒後增加約25nm左右。拉曼光譜確認成功摻雜元素進入二氧化鈰奈米粒子，發現隨摻雜元素濃度提高F2g mod波峰中心(Xc)有位移、半高寬增加現象，顯示晶粒經摻雜膨脹及扭曲。在X光吸收圖譜技術(XAFS)中，XANES(X-ray Absorption Near Edge Structure)顯示樣品無短程有序鋁與銅氧化物存在，發現摻雜銅5%樣品Ce(III)比例達20%；EXAFS(Extended X-Ray Absorption Fine Structure)結果得知銅為取代在二氧化鈰晶格之中。由SQUID磁性量測顯示未摻雜二氧化鈰為順磁性、經低濃度銅摻雜樣品為鐵磁性、鋁摻雜後鐵磁性有消失現象，對照XANES圖譜樣品發現銅離子”價態”有改變的趨勢。

In this thesis, we study the magnetic behaviors of Al-Cu codoped CeO2 nanocrystals. The samples were synthesized by thermal decomposition method. A variety of experimental methods such as x-ray diffraction (XRD), Raman spectroscopy, x-ray absorption fine structures (XAFS), and superconducting quantum interference device (SQUID) have been used to investigate the structures and physical properties of the materials.
Since the undoped CeO2, metallic copper (Cu) and aluminum (Al), as well as possible Cu or Al-based secondary phases, are not ferromagnetic, the appearance of ferromagnetism in the samples is a very intriguing research topic. Our x-ray diffraction (XRD) data shows only CeO2 peaks and therefore the possible formation of CuO and Al2O3 second phases can be excluded. This observation is also supported by the results of Raman spectroscopy and x-ray absorption near edge structure (XANES).
Magnetic properties of the samples were measured by the superconducting quantum interference device (SQUID) at room temperature. The 5% Cu-doped CeO2 sample exhibits room-temperature ferromagnetism while the pure CeO2 appears to be paramagnetic. However the room-temperature ferromagnetic behavior is destroyed by the addition of Al. The XANES analysis revealed that the content of Ce3+ ions in CeO2 was largely increased by incorporating 5% of Cu dopant atoms. On the other hand, addition of Al can lead to substantial decrease of Ce3+ content. By comparing the XANES spectra of doped samples with different Cu and Al concentration, we conclude that the addition of aluminum ions can effectively change the valence state of Cu and thus destroy ferromagnetism in these materials.

目錄
第一章　序論
1-1　研究動機 1
1-2　論文簡介 1
第二章　理論與文獻回顧
2-1　二氧化鈰材料介紹 2
2-2　稀磁性氧化物 4
2-3 　DMO磁性理論 5
2-3-1　超交換作用 5
2-3-2　雙交換作用 6
2-3-3　RKKY交換作用 7
2-3-4　BMP理論 8
2-3-5　CTF理論 9
2-4　奈米CeO2鐵磁性來源 11
第三章　實驗原理及方法
3-1　X光繞射(X-ray diffraction; XRD) 13
3-2　超導量子干涉(SQUID) 15
3-3　拉曼光譜(Raman spectroscopy) 16
3-4　感應耦合電漿質譜儀(Inductively Coupled Plasma Mass. Spectrometry; ICP-MS) 18
3-5　X光吸收精密結構(X-ray absorption fine structure ; XAFS) 19

第四章　實驗原理及方法
4-1　樣品製備 27
4-2　實驗藥劑 28
4-3　製備流程 28
4-4　氣氛退火 31
4-5　樣品名稱 32
第五章　實驗結果數據分析與討論
5-1　X光繞射分析(XRD) 34
5-2　拉曼光譜分析(Raman spectroscopy) 37
5-3　X光吸收精密結構分析(XAFS) 41
5-3-1　近邊 X光吸收精密結構分析(XANES) 45
5-3-2　延伸 X光吸收精密結構分析(EXAFS) 52
5-4　超導量子干涉儀分析(SQUID) 59
第六章　結果與討論 61
參考文獻 62

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