淡江大學機構典藏:Item 987654321/32511
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    Please use this identifier to cite or link to this item: https://tkuir.lib.tku.edu.tw/dspace/handle/987654321/32511


    Title: 利用X-ray吸收光譜研究Pr0.5Ba0.5MnO3之電子與原子結構
    Other Titles: Electronic and atomic structures of Pr0.5Ba0.5MnO3 studied by X-ray absorption spectroscopy
    Authors: 黃貽筠;Huang, I-yun
    Contributors: 淡江大學物理學系碩士班
    彭維鋒;Pong, Way-faung
    Keywords: X光吸收近邊緣結構;延伸 Ｘ光吸收精細結構;龐磁阻;XANES;EXAFS;CMR;A-site ordered
    Date: 2009
    Issue Date: 2010-01-11 02:15:28 (UTC+8)
    Abstract: X光吸收光譜(X-ray Absorption Spectroscopy，XAS)之X光吸收近邊緣結構(X-ray absorption near-edge structure，XANES)以及延伸Ｘ光吸收精細結構（Extended X-ray absorption fine structure，EXAFS）研究鈣鈦礦結構（perovskite-type）中A位置原子排列有序之Pr0.5Ba0.5MnO3電子結構與原子結構在不同磁相變點之特性。在此樣品中有兩種磁相轉變；居禮溫度位於311 K與尼爾溫度位於265 K。由Ｘ光吸收精細結構光譜發現於尼爾溫度時有很強的楊-泰勒形變，並且由X光吸收近邊緣結構中可見於此溫度時電子自旋方向較無序，相對於居禮溫度時楊-泰勒形變弱且電子自旋方向有序。經由此研究結果發現樣品中原子結構扭曲時電子不易於錳與氧間傳遞形成反鐵磁態。當扭曲不明顯時電子易於錳與氧間傳遞而形成鐵磁態。
    In this study, we have investigated temperature-dependent magnetic properties of the half-doped perovskite-type manganese oxide Pr0.5Ba0.5MnO3 at different phase transitions using x-ray absorption near-edge structure (XANES) and extended x-ray absorption fine structure (EXAFS) spectroscopies. The Pr0.5Ba0.5MnO3 shows Curie (TC) and Néel (TN) temperature at 311 K and 265 K, respectively. The EXAFS spectra show strong and weak Jahn-Teller distortion at TN and TC respectively, while the XANES indicates the disordered and ordered spin direction severally. Via the research, the hopping energy increases and decreases at TN and Tc respectively due to strong or weak atomic distortion.
    Appears in Collections:[Graduate Institute & Department of Physics] Thesis

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