臺灣博碩士論文加值系統

在本論文中，我們利用溶膠-凝膠法與固態反應法製備(Bi0.9Gd0.1)(Fe1-xCrx)O3 (BGFCO, x = 0, 0.05, 0.1, 0.15, 0.2)複鐵性塊材，探討摻雜Gd及Cr後對結構、熱膨脹係數、微結構及磁、電性質的影響。
BGFCO複鐵性塊材在空氣環境下，分別經720-900 °C的溫度燒結，在16小時燒結時間下，所有樣品的相對密度皆在60%以上。BiFeO3出現較多雜相，添加10 mol% Gd後，雜相明顯降低，再隨Cr添加量增加，主要繞射峰(104)、(110)強度明顯降低，(201)會成為最強繞射峰。以SEM分別在200、3000、10000 X的倍率下，觀察其微結構變化，結果發現添加10 mol% Gd後，孔洞明顯變小，晶粒形狀為橢圓形，隨Cr添加量增加，形狀轉為方形。熱膨脹係數量測溫度範圍在24-180℃，在相同組成比例下，溶膠-凝膠法製備之塊材的熱膨脹係數皆低於固態反應法，其中溶膠-凝膠法製備之g-(Bi0.9Gd0.1)(Fe0.95Cr0.05)O3有最小的熱膨脹係數值7.29 μm/m℃。
網路分析儀在共振腔頻率為7 GHz下，分別使用7、8、10 GHz之微波量測介電性質和7.5、9、11 GHz之微波量測磁性質。溶膠-凝膠法製備之g-(Bi0.9Gd0.1)(Fe0.95Cr0.05)O3在7 GHz有最大介電常數7.625 ；溶膠-凝膠法製備之g-BiFeO3在7 GHz時，有最小介電損失0.00096。溶膠-凝膠法製備之g-(Bi0.9Gd0.1)(Fe0.95Cr0.05)O3在7.5 GHz時，有最大導磁率28.721；固態反應法製備之s-(Bi0.9Gd0.1)(Fe0.9Cr0.1)O3在7.5 GHz時，有最小磁損率0.063。

In this study, (Bi0.9Gd0.1)(Fe1-xCrx)O3 (BGFCO, x = 0, 0.05, 0.1, 0.15, 0.2) multiferroic materials were prepared by sol-gel and solid-state methods. The effects of doping Gd and Cr on the structure, thermal expansion coefficient, microstructure, and magnetic and dielectrical properties have been investigated.
The multiferroic materials were sintered for 16 hours at the temperature of 720-900℃ in the atmospheric environment. The relative densities of multiferroic materials were all above 60%. The XRD result showed that heterogeneous phase was reduced after doping 10 mol% Gd. When the doping amount of Cr increased, the signal of (201) was higher than those of (104) and (110) and became the main diffraction peak. The variations of microstructure were observed by using SEM at magnifications of 200, 3000, and 10000X, respectively. The voids became smaller after doping 10 mol% Gd and the grain shape was elliptical. When the doping amount of Cr increased, the grain shape transferred to square. The coefficients of thermal expansion of the multiferroic materials prepared by the sol-gel method were lower than those prepared by solid-state method at the same composition ratios. The g-(Bi0.9Gd0.1)(Fe0.95Cr0.05)O3 prepared by sol-gel method possessed a minimum coefficient of thermal expansions of 7.29 μm/moC.
By using network analyzer with a resonator frequency of 7 GHz, dielectric properties were measured by microwaves of 7, 8, and 10 GHz, respectively. Magnetic properties were measured by microwaves of 7.5, 9, and 11 GHz, respectively. The g-(Bi0.9Gd0.1)(Fe0.95Cr0.05)O3 and the g-BiFeO3 prepared by sol-gel method possessed a maximum dielectric constant of 7.625 and a minimum dielectric loss of 0.00096 at 7 GHz, respectively. The g-(Bi0.9Gd0.1)(Fe0.95Cr0.05)O3 prepared by sol-gel method and s-(Bi0.9Gd0.1)(Fe0.9Cr0.1)O3 prepared by solid state method possessed a maximum permeability of 28.721 and a minimum magnetic loss of 0.063 at 7.5 GHz, respectively.

摘要 I
Abstract III
目錄 V
表目錄 VIII
圖目錄 IX
1-1 前言 1
1-2 研究目的與動機 2
第二章 文獻回顧 3
2-1 鈣鈦礦材料特性 3
2-2 鉍鐵氧(BiFeO3)的基本性質 6
2-2-1 晶體結構 6
2-2-2 鐵電性質 8
2-2-3 磁性質 10
2-3 摻雜第三元素改質 12
2-3-1 摻雜Gd 14
2-3-2 摻雜Cr 15
2-4 製備方法 16
2-4-1 溶膠-凝膠法 16
2-4-2 固態反應法 20
第三章 實驗方法及設備 22
3-1 實驗藥品 23
3-2 粉體之製備 24
3-2-1 溶膠-凝膠法製備粉體 24
3-2-2 固態反應法製備粉體 26
3-3 複鐵性塊材之製備 28
3-4 性質測量與分析 30
3-4-1 塊材密度量測 31
3-4-2 X光繞射分析儀 (x-ray diffraction, XRD) 31
3-4-3 掃描式電子顯微鏡 (scanning electron microscope, SEM) 31
3-4-4 熱機械分析儀 (thermal mechanical analysis, TMA) 31
3-4-5 網路分析儀 (network analyzer) 32
第四章 結果與討論 32
4-1 密度測量 33
4-2 XRD結構分析 35
4-3 表面微結構 39
4-4 熱性質分析 52
4-5 磁電性質分析 54
4-5-1 介電性質分析 54
4-5-2 磁性質分析 65
第五章 結論 75
參考文獻 78
附錄 85
1. 理論密度計算 85
2. 介電性質計算 88
3. 磁性質計算 89

表目錄
表2-1 BiFeO3摻雜之第三元素及其修飾性質 13
表3-1 樣品組成比例 22
表3-2 溶膠-凝膠法製備g-BGFCO塊材與燒結溫度關係 29
表3-3 固態反應法製備s-BGFCO塊材與燒結溫度關係 29
表4-1 複鐵性塊材之平均粒徑大小 51

圖目錄
圖2.1 鈣鈦礦結構 3
圖2.2 鐵酸鉍於(111)方向極化時，鐵離子相對於氧八面體的位移量 4
圖2.3 隨溫度的改變，鈣鈦礦結構晶體上的變化 5
圖2.4 BiFeO3結構 6
圖2.5 BiFeO3相轉變溫度圖 7
圖2.6 BiFeO3單晶(上)與薄膜(下)之鐵電極化大小 8
圖2.7 BiFeO3六方晶的自旋結構 11
圖2.8 溶膠-凝膠法的反應程序 19
圖2.9 磨球在罐中運動的情形 21
圖3.1 溶膠-凝膠法製作複鐵性塊材流程圖 25
圖3.2 固態反應法製作複鐵性塊材流程圖 27
圖3.3 BGFCO燒結條件 29
圖3.4 BGFCO塊材性質量測流程圖 30
圖4.1 BGFCO複鐵性塊材之相對密度變化圖 34
圖4.2 標準BiFeO3 XRD繞射圖譜 35
圖4.3 溶膠-凝膠法製備之複鐵性塊材XRD繞射圖 36
圖4.4 固態反應法製備之複鐵性塊材XRD繞射圖 37
圖4.5 溶膠-凝膠法製備之複鐵性塊材SEM微結構圖，放大倍率200倍 40
圖4.6 固態反應法製備之複鐵性塊材SEM微結構圖，放大倍率200倍 41
圖4.7 溶膠-凝膠法製備之複鐵性塊材SEM微結構圖，放大倍率3000倍 43
圖4.8 固態反應法製備之複鐵性塊材SEM微結構圖，放大倍率3000倍 44
圖4.9 溶膠-凝膠法製備之複鐵性塊材SEM微結構圖，放大倍率10000倍 46
圖4.10 固態反應法製備之複鐵性塊材SEM微結構圖，放大倍率10000倍 47
圖4.11 固態反應法製備之s-(Bi0.9Gd0.1)(Fe0.85Cr0.15)O3複鐵性塊材，其
大晶粒之EDS元素含量比例圖 48
圖4.12 固態反應法製備之s-(Bi0.9Gd0.1)(Fe0.85Cr0.15)O3複鐵性塊材，其
小晶粒之EDS元素含量比例圖 49
圖4.13 BGFCO複鐵性塊材之熱膨脹係數變化圖 53
圖4.14 BGFCO複鐵性塊材在7 GHz下之介電常數變化圖 55
圖4.15 BGFCO複鐵性塊材在7 GHz下之介電損失變化圖 56
圖4.16 BGFCO複鐵性塊材在8 GHz下之介電常數變化圖 57
圖4.17 BGFCO複鐵性塊材在8 GHz下之介電損失變化圖 58
圖4.18 BGFCO複鐵性塊材在10 GHz下之介電常數變化圖 59
圖4.19 BGFCO複鐵性塊材在10 GHz下之介電損失變化圖 60
圖4.20 溶膠-凝膠法製備之複鐵性塊材在不同頻率下介電常數變化圖 61
圖4.21 溶膠-凝膠法製備之複鐵性塊材在不同頻率下介電損失變化圖 62
圖4.22 固態反應法製備之複鐵性塊材在不同頻率下介電常數變化圖 63
圖4.23 固態反應法製備之複鐵性塊材在不同頻率下介電損失變化圖 64
圖4.24 BGFCO複鐵性塊材在7.5 GHz下之導磁率變化圖 65
圖4.25 BGFCO複鐵性塊材在7.5 GHz下之磁損率變化圖 66
圖4.26 BGFCO複鐵性塊材在9 GHz下之導磁率變化圖 67
圖4.27 BGFCO複鐵性塊材在9 GHz下之磁損率變化圖 68
圖4.28 BGFCO複鐵性塊材在11 GHz下之導磁率變化圖 69
圖4.29 BGFCO複鐵性塊材在11 GHz下之磁損率變化圖 70
圖4.30 溶膠-凝膠法製備之複鐵性塊材在不同頻率下導磁率變化圖 71
圖4.31 溶膠-凝膠法製備之複鐵性塊材在不同頻率下磁損率變化圖 72
圖4.32 固態反應法製備之複鐵性塊材在不同頻率下導磁率變化圖 73
圖4.33 固態反應法製備之複鐵性塊材在不同頻率下磁損率變化圖 74

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