English  |  正體中文  |  简体中文  |  全文筆數/總筆數 : 57505/91038 (63%)
造訪人次 : 13428157      線上人數 : 344
RC Version 7.0 © Powered By DSPACE, MIT. Enhanced by NTU Library & TKU Library IR team.
搜尋範圍 查詢小技巧:
  • 您可在西文檢索詞彙前後加上"雙引號",以獲取較精準的檢索結果
  • 若欲以作者姓名搜尋,建議至進階搜尋限定作者欄位,可獲得較完整資料
  • 進階搜尋
    請使用永久網址來引用或連結此文件: http://tkuir.lib.tku.edu.tw:8080/dspace/handle/987654321/108013

    題名: X-ray scattering studies of CDW modulated structures in Ba1-xKxBiO3
    作者: 杜昭宏
    貢獻者: 淡江大學物理學學系
    日期: 1996
    上傳時間: 2016-10-19 11:51:13 (UTC+8)
    摘要: The correlation between charge-density waves (CDWs) and superconductivity has been a subject of extensive study for a long time. This thesis describes a series of x-ray scattering experiments designed to study CDWs in perovskite superconductors. A review of the properties of CDW materials and the relationship between CDWs and superconductivity is given. Using x-ray scattering techniques the modulated structures caused by the formation of a CDW state have been clarified in a variety of single crystals of Ba1-xKxBiO3. In low resolution measurements, the CDW satellites produce a superstructure doubling the unit cell existing in the range from the semiconducting state (00.37), even in the low temperature superconducting state. Additional peaks with G2 = 0.33a* were observed, which are only present in semiconducting samples. An attempt to determine the size of the modulated structure was undertaken using higher resolution x-ray scattering in the superconductor Ba0.6K0.4BiO3. In this study, the modulated structure was identified to be incommensurate with the host lattice with G1=0.494a* ± 0.11b* and a rather short correlation length of ˜150Å limited by the CDW domain size. An unusual decrease in the intensities of the CDW superlattice reflections was also observed as the temperature was lowered. Evidence to support to the attribution of these satellites to a CDW distortion was obtained from measurements conducted under applied magnetic fields. Increased splitting of the CDW satellites was observed under a magnetic field of 0.8 T with an extremely long relaxation time when the field was removed. Such a long relaxation time is a characteristic of CDWs associated with metastable states.
    顯示於類別:[物理學系暨研究所] 學位論文


    檔案 描述 大小格式瀏覽次數
    目次.pdf645KbAdobe PDF81檢視/開啟



    DSpace Software Copyright © 2002-2004  MIT &  Hewlett-Packard  /   Enhanced by   NTU Library & TKU Library IR teams. Copyright ©   - 回饋