臺灣博碩士論文加值系統

我們藉鋰釩鉬酸鹽助熔劑法（lithiumvanadomolybdate flux method）製備實驗樣品直頑火輝石（orthoenstatite，MgSiO3），並利用美國康乃爾大學CHESS的B1實驗室進行同步輻射Ｘ光能量擴散分析法（Energy-dispersive analysis），分析直頑火輝石常溫高壓下的相變情形。
實驗中我們對直頑火輝石樣品加壓至21.4 GPa，發現超過8 GPa時X-ray繞射峰發生變化，且於10 GPa左右有晶面間距-壓力圖斜率改變的情形，推論相變壓力應在10 GPa左右，而直頑火輝石之晶格參數與晶胞體積隨壓力變化的關係式如下：
相變前（0 ~ 10 GPa）：
a（Å）= 18.23 — 0.0446 P（GPa）+ 0.00186 P2
b（Å）= 8.831 — 0.0567 P（GPa）+ 0.00215 P2
c（Å）= 5.224 — 0.0032 P（GPa）— 0.00061 P2
V（Å3） = 840.907 — 7.306 P（GPa）+ 0.1293 P2
V/V0 = 1.00 — 0.0087 P（GPa）+ 0.00015 P2

The phase transformation of a synthetic orthoenstatite (MgSiO3) has been studied by X-ray energy dispersive analysis at room temperature and up to 21.4 GPa. The sample was synthesized using the lithiumvanadomolybdate flux method. The synchrotron radiation from B1 laboratory of CHESS in Cornell University was used as the X-ray source.
It is found that some diffraction lines of orthoenstatite disappeared at pressure above 8 GPa, and then followed by a change in the slopes of all d-spacing — Pressure (or energy - Pressure) plots at 10 GPa. This observation suggests that a phase transition in orthoenstatite has taken place under compression. The pressure dependences of lattice parameters and unit cell volume for orthoenstatite can be described as follow :
For orthoenstatite（0 ~ 10 GPa）：
a（Å）= 18.23 — 0.0446 P（GPa）+ 0.00186 P2
b（Å）= 8.831 — 0.0567 P（GPa）+ 0.00215 P2
c（Å）= 5.224 — 0.0032 P（GPa）— 0.00061 P2
V（Å3） = 840.907 — 7.306 P（GPa）+ 0.1293 P2
V/V0 = 1.00 — 0.0087 P（GPa）+ 0.00015 P2

目錄
中文摘要………………………………………………………………..Ⅰ
英文摘要………………………………………………………………..Ⅱ
謝誌……………………………………………………………………..Ⅲ
目錄……………………………………………………………….…….Ⅳ
表目錄………………………………………………………..…………Ⅵ
圖目錄…………………………………………………………………..Ⅶ
第一章 緒論………………………………………………….….….1
1.1 前人研究…………………………………………………………1
1.2 研究目的…………………………………………………………12
第二章 實驗方法………………………………………………….…14
2.1 鑽石高壓砧技術…………………………………………………14
2.1.1 鑽石高壓砧結構和原理……………………………………14
2.1.2 鑽石壓砧平行度調整………………………………………18
2.1.3 樣品腔的獲得………………………………………………19
2.1.4 壓力的量測…………………………………………………21
2.1.5 傳壓介質……………………………………………………21
2.1.6 裝入樣品……………………………………………………22
2.1.7 壓力值及樣品信號量測及加壓……………………………22
2.2 同步輻射 X-ray 光譜技術……………………………….……23
2.2.1 X光繞射原理…………………………………………….…23
2.2.2 能量擴散分析法…….………………………………….…24
2.3 樣品的製備與分析………………………………………………25
2.3.1 樣品的製備…………………………………………………25
2.3.2 樣品的分析…………………………………………………26
第三章 實驗結果……………………………………………..…….30
3.1 加壓後orthoenstatite繞射圖譜………………………………30
3.2 加壓後的晶面間距變化情形……………………………………39
3.3 加壓後晶格參數與體積的變化情形……………………………43
第四章 討論……………………………………………………….…50
4.1 繞射峰之探討……………………….……………………….…58
4.2 Pbca→ high-P C2/c？…………………………...………….58
4.3 晶格參數與體積之探討…………………………………………60
4.4 相變的可逆性……………………………………………………60
第五章 結論……………………………………………………….…64
第六章 後續工作………………………………………………….…66
參考文獻……………………………………………………………..…67

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中文部分
余樹楨著, 晶體之結構與性質, 渤海堂文化公司印行, 中華民國85年.
林志明, 超高壓技術簡介─應用於半導體相變研究, 物理雙月刊二十卷五期, P.600, 中華民國八十七年十月.