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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/71664

    Title: 磷摻雜對鐵基超導LaOFeAs1-xPx的晶格熱膨脹與電子轉移之影響
    Authors: 羅詔駿;Lo,Chao-Chun
    Contributors: 物理學系
    Keywords: 鐵基超導;熱膨脹;電子轉移
    Date: 2016-07-05
    Issue Date: 2016-10-13 13:28:51 (UTC+8)
    Publisher: 國立中央大學
    Abstract: 自2006年鐵基超導體被發現至今,鐵基超導的超導溫度和形成庫柏對的機制等各種特性不停被研究探討,不斷有團隊提出新的實驗結果或是新合成的鐵基超導種類,以討論鐵基超導體材料的基本原理和未來發展。本論文中實驗樣品主要為”1111”鐵基超導體系中的層狀材料LaOFeAs1-xPx,磷摻雜量x分別為0.4、0.44、0.46、0.48、0.5和0.56等六個樣品。論文中主要分三大部分探討,首先為常溫下結構變化,藉由X光繞射可以得知隨磷摻雜量x增加,晶格常數隨之縮小,FeAs層的厚度和鍵長鍵角變化趨勢相同;再透過變溫中子散射獲得x=0.4、x=0.44和x=0.48三個樣品的晶格常數隨溫度變化,獲得x=0.44的樣品其晶格常數相較350 K時變化率最小,另外兩個樣品的晶格常數相較350 K時變化率大約0.3%;第三部分則是探討不同溫度下的電子轉移,透過變溫X光繞射可以轉換獲得電子雲圖,經由比較各離子層電子雲圖發現無論在75 K,195 K或是常溫時隨磷摻雜量x增加,電子分佈都有漸漸往FeAs層和LaO層之間移動的趨勢,可能因此造成磁性出現。;LaOFeAs₁-xPx is one of the iron-based superconductor with layer structure. We studied the effects of P-doping and temperature on the structure and charge distribution of iron-based superconductor LaOFeAs₁-xPx (x=0.4-0.56). By refining X -ray diffraction and neutron diffraction patterns with General Structure Analysis System (GSAS) program, we could get the information of structure and the distribution of charge density after using fourier transform.
    In our study, the lattice constants decrease as the P-doping increase at room temperature. The thickness in the Fe-As layer and the P-doping are not directly related, and the bond length and bond angles are not either. The lattice constants decrease as the temperature decrease. The max variation in three samples (x=0.4, 0.44, 0.48) of lattice constants form 3 K to 350 K is about 0.3%.
    There is the same trend of the charge distribution at 75 K, 195K and room temperature between three samples (x=0.4, 0.44, 0.48). The trend is that the charge between Fe-As layer and La-O layer will increase. The shift of charge may bring about growth and decline of magnetic.
    Appears in Collections:[物理研究所] 博碩士論文

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