應用X光粉末繞射及吸收光譜鑑定稀磁半導體Cd1-xFexS及[Cu(phen)Cl2]2錯合物

Characterization of Dilute Magnetic Semiconductors Cd1-xFexS and [Cu(phen)Cl2]2 Complex by Powder X-Ray Diffraction and X-Ray Absorption Spectroscopy

陳緒騰(Hsu-Teng Cheng)

指導教授 ： 許益瑞

國立臺北科技大學/工程學院/有機高分子研究所/碩士(2012年)

摘要

在此論文中主要利用粉末X光繞射來研究CdS的高壓相變行為在壓力為11.00 GPa以下及對於不同濃度之Fe的Cd1-xFexS樣品 (x = 0.01, 0.03, 0.05, 0.08 和 0.16)的Fe參雜效應。並藉由general structure analysis system (GSAS) 軟體之Rietveld精算之結果顯示，對於CdS樣品由纖鋅礦結構轉變為氯化鈉結構的相變壓力(Pt)為2.29 GPa。相較於先前的研究，本實驗中CdS的Pt (2.29 GPa)皆低於其他研究的結果(Pt = 2.5 ~ 3.1 GPa)。除了鐵含量為0.01的硫化鐵鎘樣品， Pt通常隨著鐵含量的增加而減少。而有趣的是，Cd0.99Fe0.01S之Pt相較於其他硫化鐵鎘之稀磁半導體是急遽下降的。為了瞭解摻鐵樣品的結構變化，也藉由鐵K吸收邊緣的延伸X光吸收精細結構(extended x-ray absorption fine structure)做為鑑定。最後基於XRD與EXAFS的Cd/Fe-S鍵長結果再做進一步的討論。另一方面，我們利用XRD和EXAFS來鑑定[Cu(phen)Cl2]2錯合物的幾何結構。並使用X光吸收近邊緣結構(x-ray absorption near edge structure)，時間依賴性密度泛函理論(time dependent density function theory)計算和超導量子干涉磁量儀(superconducting quantum interference device magnetometer)來研究其電子結構。

關鍵字

稀磁半導體 ； 高壓 ； 纖鋅礦 ； 氯化鈉 ； 相變 ； X光粉末繞射 ； X光吸收光譜

並列摘要

In this thesis, the powder X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) are used to study the pressure-induced phase transitions of CdS below 11.00 GPa and the variation of Fe concentration doped effect on Cd1-xFexS (x = 0.01, 0.03, 0.05, 0.08 and 0.16) DMS. The Rietveld refinement results by the general structure analysis system (GSAS) package indicate that the phase transition pressure (Pt) from the wurtzite type to sodium chloride type for CdS occurred at 2.29 GPa. In comparison with those previous study on CdS, the Pt of our result is lower than those of them with Pt around 2.5 ~ 3.1 GPa. In general, Pt is decreased with the increasing of dopant Fe concentration, except that the nominal composition of x equals to 0.01. Interestingly, the Pt of Cd0.99Fe0.01S is decreased prominently than any other DMS of Cd1-xFexS. In order to realize the structural variations on these Fe dopant samples, these structures are also characterized by EXAFS of Fe K-edge. The discussions based on the results of Cd/Fe-S bond lengths obtained from XRD and EXAFS are made in this work. On the other hand, the geometric structure of Cu complex, [Cu(phen)Cl2]2, is confirmed by XRD and EXAFS. Moreover, the electronic structure is studied by XANES, time dependent density function theory (TD-DFT) calculation and superconducting quantum interference device magnetometer (SQUID).

並列關鍵字

dilute magnetic semiconductors (DMS) ； high pressure ； wurtzite ； NaCl type ； phase transition ； X-ray diffraction (XRD) ； X-ray absorption spectroscopy (XAS)

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