臺灣博碩士論文加值系統

利用X-光對La1-xSrxFeO3之吸收光譜O K-edge，Fe LⅢ，Ⅱ-edge K-edge及La LⅢ，LⅡ-edges來探討其電子結構及一些已知的物理相關現象。觀察Fe K-edge的吸收光譜中的化學位移顯示出Fe的價電數隨Sr參雜而增加，直至x=0.8才出現飽和狀態。與象徵pre-edge的強度的3d電洞成線性比。在另一方面La的LⅢ，LⅡ吸收光譜中，吸收強度的不同象徵La的區域結構及電子態皆因Sr的參雜而有所改變。本文中將討論La1-xSrxFeO3中Fe的電子價及結構的變化，並定性的從La 延伸X-光吸收精細結構看出周遭的原子結構變化。

The O K-edge, Fe LⅢ，Ⅱ-edge Fe K-edge and La LⅢ，LⅡ-edge x-ray absorption spectroscopy (XAS) studies of a series of La1-xSrxFeO3 samples are presented. The chemical shift and the pre-edge feature strength of Fe K-edge spectra show that both the Fe valence and its 3d holes increase with Sr concentration up to x = 0.8 then saturate. Systematic variations in the whiteline intensity and the above-edge feature in the La LⅢ，LⅡ-edge XAS spectra with Sr concentration indicate that the local structure and the electronic state of La are both affected by Sr doping. Results of EXAFS (Extend X-ray Absorption Fine Structure) study show systematic variation of La local environment with Sr concentration. The correlation between the Fe valence change and the structural variation are discussed.

第一章 樣品簡介………………………………………1
第二章 X-光吸收光譜簡介…………………………… 4
壹. X-光吸收光譜基本理論……………………………4
(一)基本原理………………………………………… 10
(二)吸收邊緣………………………………………… 11
(三)吸收係數………………………………………… 14
貳. XANES原理……………………………………… 16
參. EXAFS原理……………………………………… 18
第三章 實驗設備與量測…………………………… 22
壹. 同步幅射光源………………………………… 22
貳. 測量方式.……………………………………… 25
參. 單色儀………………………………………… 26
肆. X-光吸收光譜測量方式……………………… 27
伍. 測量樣品的處理與準備……………………… 29
陸. 實驗流程……………………………………… 30
第四章 數據分析………………………………………32
X-光吸收光譜之數據分析流程………………………32
XANES(一)決定Eo…………………………………… 33
(二)去除glich……………………………………… 34
(三)扣除邊緣前背景……………………………… 35
(四)歸一過程……………………………………… 35
EXAFS (五)加權因數………………………………… 36
(六)窗扉含數……………………………………… 36
(七)傅立葉轉換…………………………………… 37
第五章 結果與討論…………………………………… 38
壹. XANES…………………………………………… 38
(一) Fe LⅢ，Ⅱ-edge……………………………… 38
(二) O K-edge…………………………………………40
(三) Fe K-edge………………………………………… 42
(四) La LⅢ，LⅡ-edge……………………………… 45
貳. EXAFS………………………………………………48
EXAFS 分析的 La LⅢ-edge………………………… 48
參. 討論與結果……………………………………… 51
第六章結論……………………………………………… 54
參考文獻 ………………………………………………… 55

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