臺灣博碩士論文加值系統

摘要
本研究主要探討的是對複鐵性陶瓷鐵酸鉍做不同比例鹼土元素(鈣,鍶,鋇)摻雜 (Bi1-xAEx)FeO3-δ (x=0.0,0.05, 0.10, and 0.15; AE= Ca, Sr, Ba)， 並在低溫環境下(從零下150度到室溫的溫度範圍內)，對此材料做拉曼的測量及研究，首先，可藉由拉曼光譜及X光繞射的實驗得知，鐵酸鉍材料為鈣鈦礦結構，室溫下空間群是R3c，菱形對稱晶系，然而，在摻雜鈣元素的情況下，會隨著其摻雜量的增加而結構發生改變，使其結構更加趨向立方晶系且變得較為對稱，另外，本文利用低溫的環境來測量鐵酸鉍材料的拉曼光譜，而藉著對各個溫度以及四個主要的峰做了fitting後，發現其頻率和半腰寬幾乎在每個不同摻雜樣品上都有較為突出的變化，此現象可以推斷鐵酸鉍材料在低溫環境下展現出自旋方向重組 (spin reorientation) ，尤其是A1(1) 與 A1(2) 模更為明顯，因鐵原子振動模主要的頻率是在150-270 cm-1之間，而A1(1) 與 A1(2) 分別的頻率大約是在 170 cm-1和220 cm-1處。

關鍵字: 鹼土元素(鈣,鍶,鋇)之鐵酸鉍摻雜,拉曼光譜, X光繞射

ABSTRACT
This work studies the temperature-dependent Raman scattering in A-site doped (Bi1-xAEx)FeO3-δ (x=0.0, 0.05, 0.10, and 0.15; AE= Ca, Sr, Ba) multiferroic ceramics in the low temperature range of -150 – 25 oC. Raman spectra and XRD reveal a rhombohedrally distorted perovskite structure with R3c space group in BiFeO3. However, the doped samples of 5 %, 10%, and 15% have a structure transition towards a nonrhombohedral symmetry with increasing Ca, Sr, and Ba concentrations. The Raman spectra of all doped BFO samples reveal a sudden change in the peak position and FWHM, especially for A1(1) and A1(2) modes. This anomaly may be attributed to an additional magnetic phase transition of spin reorientation. Fe atoms are mainly involved in vibration modes between 150 and 270 cm−1 and A1(1) and A1(2) modes are approximately at ~170 and ~220 cm-1, respectively.

Keywords : alkaline-earth (Ca, Sr, Ba) doped BiFeO3, Raman scattering, X-ray diffraction

致謝
首先，我要感謝杜繼舜教授這幾年來無私的教導，他不僅僅是在研究上或是生活上的大小事，都給很多很棒的意見，老師非常積極地帶領著我們，這是一個很棒的團隊，另外，老師他更是積極且平時不斷地督促我們的進度，並時常要求一定要擁有獨立思考的能力，此外，老師如果有新的想法便會在晚上的時候到實驗室討論，以及聊聊最近過得如何等關心的話語，他是一位值得我們尊敬的老師。感謝「明志科技大學」陳炳宜教授與「華夏科技大學」陳正劭教授，兩位教授都在實驗與分析上給予我很多的幫助。十分地感謝洪正銘學長 ，學長他除了研究方面給予了相當多的幫助，並且也時常在閒暇之餘與我們一起跑去打球及運動，另外，每次去「新竹國家同步中心」做實驗，學長一定都會出車載我們，並且在回程的時候，也都是想著要早點把我們都送回家，真的是一位很棒的學長，與其說他是學長，不如說他更像朋友。感謝林張鴻學長與江明達學長，當時我還是個甚麼都不懂才剛踏進實驗室做實驗的專題生，是他們在平時在實驗方面適時的給予教導，包括實驗儀器的操作以及如何讀實驗相關文章，從而得到你要的資訊，此外，小風更是我們實驗室的開心果，由他的帶動下，實驗室上下無處不是他所帶給我們的快樂及笑聲，達哥更是教我要不斷地用積極的態度面對許多遇到的問題。感謝王聖棻學姐、張庭綸學長、柴志剛學長、吳泓叡、陳柏翰、李宏彥、呂明權，不論是一起做實驗奮鬥的日子，還是生活上快樂的相處，都是很棒的回憶。感謝丁翊與許哲睿，丁翊真的是位所謂的良師益友，不論是實驗方面或是生活方面，他都是位能侃侃而談的人，與他共事的那段日子，他真的能讓你感受到他那對任何事情都有著無與倫比的執著以及超群認真的態度，在這種氛圍下做事，你又怎能不與他一起奮鬥呢，而我從哲睿身上所學到的是，與其說他對實驗的熱忱，不如說他更想不斷地嘗試新的事物，雖然他總是默默地一個人完成他分內的事，但我想那就是一種對工作上應有的態度。感謝學弟妹彭憶婷、張立韻、林俊諺、張鈞策、吳芮瑩，就是因為有你們這些夥伴，才能一起在實驗室度過的美好時光，更重要的是，有你們平時的支持才有現在的我，實驗方面也給了我很多意見，而生活上，一起相處的愉快是不會騙人的。最後，要感謝我的家人，雖然我不常回家，但他們還是默默地支持我，並時常關心著我，即使他們無法在這方面給我甚麼意見，但是沒有甚麼可以比得上他們的陪伴，這兩年來真的是感謝所有的親友們帶給我很多幫助。
CONTENTS
ABSTRACT ………………………………………………………...ⅰ
摘要……………………………………………………………………..ⅱ
致謝……………………………………………………………………..ⅲ
CONTENTS…………………………………………………………….ⅴ
LIST OF FIGURES……………………………………………………..ⅶ
LIST OF TABLES………………………………………………………ⅹ
Chapter 1 Introduction……………………………………………………1
1.1 Background………………………………………………………1
1.2 Motivation………………………………………………………..1
1.3 Characteristic of BiFeO3 Ceramic…………………….………….2
1.4 Raman mode……………………………………………………..4
Chapter 2 Theoretical Analysis…………………………………………..5
2.1 X-ray Diffraction (Bragg’s Law)………………………………...5
2.2 Raman Spectroscopy…………………………………………….6
2.2.1 Light scattering……………………………………………6
2.2.2 Classical electromagnetic theory………………………….8
Chapter 3 Experimental Procedures…………………………………….13
3.1 Alkaline-earth (Ca, Sr, Ba)-doped BiFeO3 preparation……………………………………………………..13
3.1.1 Mixing powder and ball milling…………………………13
3.1.2 Dry and filtering…...……………………………………..14
3.1.3 Calcining…………………………………………………14
3.1.4 Planetary ball milling…………………………………….15
3.1.5 Pressing…………………………………………………..15
3.1.6 Sintering………………………………………………….15
3.2 Raman spectroscopy……………………………………………16
Chapter 4 Results and Discussion………………………………………17
4.1 Structure………………………………………………………...17
4.2 Raman spectra…………………………………………………..19
4.2.1 Raman fitting…………………………………………….26
4.2.2 Raman shift and FWHM vs. temperature……………..…35
4.3 Raman modes of different contents with Ca, Sr, Ba doped BFO
…………………………………………………………………41
Chapter 5 Conclusions………………………………………………….42
References………………………………………………………………43















LIST OF FIGURES
Figure 1.1 Unit cell of perovskite structure………………………………3
Figure 1.2 Rhombohedral unit cell of bismuth ferrite……………………3
Figure 1.3 (a) antiferromagnetic of G-type and (b) sum of the magnetic moment of iron atoms is not zero…………………………….4
Figure 1.4 (a) Total area normalized Raman spectra of polycrystalline BiFeO3 in parallel and crossed polarization configuration. (b) Fits of Raman peaks corresponding to various modes.............5
Figure 2.1 Bragg’s law…………………………………………………...5
Figure 2.2 Vibrational and electronic excitations of Raman scattering : (a) no exchange of energy: incident and scattered photons have the same energy (b) Atom or molecule absorbs energy, scattered photon has less energy than the incident photon (c) Atom or molecule loses energy: scattered photon has more energy than the incident photon……………………………...7
Figure 2.3 Simple harmonic motion………………..…………………….9
Figure 2.4 Vibrational and electronic excitations of Raman scattering
..............................................................................................11
Figure 3.1 (Ca, Sr, Ba)-doped BiFeO3 Sample Preparation…………….13
Figure 3.2 Calcining process…………………………………...……….15
Figure 3.3 Sintering process…………………………………………….16
Figure 4.1 X-ray diffraction of Ca-doped BiFeO3 ceramics……………18
Figure 4.2 X-ray diffraction of Sr-doped BiFeO3 ceramics…………….18
Figure 4.3 X-ray diffraction of Ba-doped BiFeO3 ceramics………...…..19
Figure 4.4 Temperature-dependent Raman spectra of BFO ceramic in the region of 0-600 cm-1………………………………………...20
Figure 4.5 Temperature-dependent in the Raman spectra of 5% Ca doped BFO ceramic is in the region of 0-600 cm-1…………..…….21
Figure 4.6 Temperature-dependent in the Raman spectra of 10% Ca doped BFO ceramic is in the region of 0-600 cm-1………..21
Figure 4.7 Temperature-dependent Raman spectra of 15% Ca doped BFO ceramic is in the region of 0-600 cm-1……………………..22
Figure 4.8 Temperature-dependent Raman spectra of 5%Sr doped BFO ceramic is in the region of 0-600 cm-1……………………..23
Figure 4.9 Temperature-dependent Raman spectra of 10% Sr doped BFO ceramic is in the region of 0-600 cm-1……………………..23
Figure 4.10 Temperature-dependent Raman spectra of 15% Sr doped BFO ceramic is in the region of 0-600 cm-1……………….24
Figure 4.11 Temperature-dependent Raman spectra of 5%Ba doped BFO ceramic is in the region of 0-600 cm-1……………………25
Figure 4.12 Temperature-dependent Raman spectra of 10% Ba doped BFO ceramic is in the region of 0-600 cm-1……………...25
Figure 4.13 Temperature-dependent Raman spectra of 15% Ba doped BFO ceramic is in the region of 0-600 cm-1……………….26
Figure 4.14 Fits of temperature-dependent Raman spectra of BFO ceramic in the region of 50-250 cm-1……………………..27
Figure 4.15 Fits of temperature-dependent Raman spectra of 5% Ca doped BFO ceramic in the region of 50-250 cm-1………....28
Figure 4.16 Fits of temperature-dependent Raman spectra of 10% Ca doped BFO ceramic in the region of 50-250 cm-1…………29
Figure 4.17 Fits of temperature-dependent Raman spectra of 5% Sr doped BFO ceramic in the region of 50-250 cm-1…..…………….30
Figure 4.18 Fits of temperature-dependent Raman spectra of 10% Sr doped BFO ceramic in the region of 50-250 cm-1..………..31
Figure 4.19 Fits of temperature-dependent Raman spectra of 15% Sr doped BFO ceramic in the region of 50-250 cm-1……..…..32
Figure 4.20 Fits of temperature-dependent Raman spectra of 5% Ba doped BFO ceramic in the region of 50-250 cm-1…..……33
Figure 4.21 Fits of temperature-dependent Raman spectra of 10% Ba doped BFO ceramic in the region of 50-250 cm-1…..……34
Figure 4.22 Fits of temperature-dependent Raman spectra of 15% Ba doped BFO ceramic in the region of 50-250 cm-1..………35
Figure 4.23 Raman shift and FWHM variation of four selected Raman modes (E(1), E(2), A1(1), and A1(2)) as a function of temperature for BFO ceramic..……………………….36
Figure 4.24 Raman shift and FWHM variation of four selected Raman modes (E(1), E(2) , A1(1), and A1(2)) as a function of temperature for 5%Ca doped BFO ceramic………...……..37
Figure 4.25 Raman shift and FWHM variation of three selected Raman modes (E(1), E(2) , A1(1), and A1(2)) as a function of temperature for 10%Ca doped BFO ceramic...……………38
Figure 4.26 Raman shift and FWHM variation of four selected Raman modes as a function of temperature for 5%Sr doping……..38
Figure 4.27 Raman shift and FWHM variation of four selected Raman modes as a function of temperature for 10%Sr doping……39
Figure 4.28 Raman shift and FWHM variation of four selected Raman modes as a function of temperature for 15%Sr doping……39
Figure 4.29 Raman shift and FWHM variation of four selected Raman modes as a function of temperature for 5%Ba doping…….40
Figure 4.30 Raman shift and FWHM variation of four selected Raman modes as a function of temperature for 10%Ba doping...…40
Figure 4.31 Raman shift and FWHM variation of four selected Raman modes as a function of temperature for 15%Ba doping…...41












LIST OF TABLES
Table 4.1 Ion radii of alkaline-earth (Ca, Sr, Ba) and Bi3+ elements……17
Table 4.2 Standard atomic weight of alkaline-earth (Ca, Sr, Ba) and Bi3+ elements………………………………………………………42
Table 4.3 Four prominent phonon modes E(1), E(2), A1(1), and A1(2) of Ca, Sr, Ba doped BFO of Raman shift at room temperature…43
Table 4.4 Four prominent phonon modes E(1), E(2), A1(1), and A1(2) of Ca, Sr, Ba doped BFO of FWHM at room temperature……...43

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