我們透過溶膠-凝膠法，成功地在二氧化矽基板中嵌入過渡金屬氧化物奈米粒子，其中嵌入濃度為0.5莫耳%、燒結溫度在700 °C~1150 °C之間，奈米粒子尺寸隨著退火溫度越高而越大。首先是氧化鐵系統，從介電係數的研究中觀察到在室溫區有一個巨大且寬廣的峰值(擴散相變)，研判是由於熱活化氧空缺效應造成的，並且在低溫區(接近65 K)發現有一個類似鐵電性的行為。從極化率的研究中也在65 K附近發現有一個相變點。感興趣的是，我們從非晶態的材料中發現了多鐵性的現象。另一方面，從磁電耦合的研究中，系統顯示出負的磁介電效應，研判是由磁場改變氧化鐵奈米粒子的電阻造成的的磁阻效應。不同尺寸磁性奈米粒子的特性，則分別透過各種實驗來鑑定，如:X光繞射儀、穿透式電子顯微鏡、X光吸收光譜作定性及定量分析。再來是氧化銅系統，從磁性與介電性的研究中發現其相變溫度都在250 K附近。我們推測這個現象的成因是由於氧化銅的多鐵性現象造成的，最後從磁電耦合的研究中，可得知此系統也顯示出負的磁介電效應。

Transitional metal oxide nanoparticles (doping 0.5 mole %) embedded in a silica glass using the sol-gel method with different annealing temperatures. For iron-oxide nanoparticles system. An interesting colossal enhancement of dielectric constant is observed around room temperature with diffuse phase transition due to the thermally activated oxygen vacancies. In addition, there is a feature observed near 65 K due to ferroelectric effect. The magnetodielectric effect observed in the glass composite is considered to be affected by magnetoresistance changes. For polarization study, we observed a transition temperature near 65 K. It is interesting to observe multiferroic phenomena in amorphous material. The characteristics of nano-magnetic iron-oxide particles were determined respectively with various techniques, such as XRD, TEM, and XANES. For cupric-oxide nanoparticles system. There is a coexistent feature observed near 250 K from magnetic and dielectric study. From magnetodielectric study, we observed this system shows a negative magnetodielectric effect.

目錄
Abstract I
論文摘要 II
目錄 III
圖目錄 VI
第一章: 簡介 1
1.1 前言 1
1.2 多鐵性材料 3
1.2.1 多鐵性材料 類型一: 磁鐵礦(Fe3O4) 4
1.2.2 多鐵性材料 類型二: 氧化銅(CuO) 5
1.3 過渡金屬氧化物 5
1.4 研究動機 6
第二章: 實驗介紹 7
2.1 樣品製備 7
2.1.1 燒結過程 9
2.2 XRD 繞射儀 10
2.3 穿透式電子顯微鏡(TEM) 12
2.4 超導量子干涉儀 14
2.5 介電性測量 17
2.6 X光吸收光譜(XAS)測量 19
第三章: 結果與討論 20
3.1 氧化鐵系統 20
3.1.1 樣品特性 (XRD & TEM) 20
3.1.2 磁化強度對溫度的關係圖 23
3.1.3 磁滯曲線 25
3.1.4交流磁化率 27
3.1.5 X光吸收近邊緣結構 29
3.1.6 介電係數特性 31
3.1.7 介電係數特性 (尺寸效應) 34
3.1.8 磁介電效應 38
3.1.9 阻抗等效電路分析 39
3.1.10 延伸X光吸收近邊緣細微結構光譜 41
3.2 氧化銅系統 42
3.2.1 樣品特性 (XRD) 42
3.2.2 介電係數特性 43
3.2.3 磁化強度與溫度的關係圖 45
3.2.4 介電係數特性 (尺寸效應) 47
第四章: 結論 48
參考文獻 50

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