異金屬鈾-鑭系鍺酸化合物之合成、結構鑑定 與性質探討; Synthesis, Crystal Structure and Properties of Heterometallic Uranyl-Lanthanide Germanates

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/60572

Title:	異金屬鈾-鑭系鍺酸化合物之合成、結構鑑定與性質探討;Synthesis, Crystal Structure and Properties of Heterometallic Uranyl-Lanthanide Germanates
Authors:	劉士溥;Liu,Shih-pu
Contributors:	化學學系
Keywords:	助熔劑合成法;鍺酸化合物;鈾;光致放光;單晶;flux synthesis;germanate;uranium;photoluminescence;single crystal
Date:	2013-07-10
Issue Date:	2013-08-22 11:41:00 (UTC+8)
Publisher:	國立中央大學
Abstract:	本研究使用助熔劑長晶法在高溫下以 KF-MoO3 作為助熔劑合成一個鈾-銪鍺酸化合物 K4[(UO2)Eu2(Ge2O7)2] (1)。以單晶 X 光繞射儀定出其結構及化學式，以及利用高溫固態合成法合成化合物 1 的純相以及等結構化合物 K4[(UO2)Sm2(Ge2O7)2] (2)，並以粉末 X 光繞射圖譜比對理論圖譜確定樣品的純度做後續分析，例如：X 光能量散佈分析、光致放光光譜等物理性質的測量。化合物 1 為一具有三維鍺酸鹽骨架的新穎六價銪–三價銪鍺酸化合物，其結構擁有 EuO7 雙五角錐以共邊方式連接形成無限鏈狀，似 PaCl5 的鍵結形式，此晶體結構擁有不尋常的陽離子–陽離子作用力的異金屬連結 U＝O – Eu。在室溫下進行放光光譜研究，由 5D0 → 7F1 與 5D0 → 7F2 的相對強度可知 Eu3+ 發光中心位在非反轉中心上。偵測其所有的放光訊號衰退曲線發現是一致的，證實只有一種 Eu3+ 放光中心，其生命期約為 0.53 ± 0.03ms。在放光光譜 450 到 550 nm 沒有看到典型的 UO22+ 放光訊號，可以證明能量轉移到 Eu3+ 放光中心或是藉由非放光過程散失掉。化合物 2 為等結構化合物，針對化合物中心金屬的放光特性，同樣進行放光光譜研究，並對研究結果做進一步探討。 A uranyl-europium germanate, K4[(UO2)Eu2(Ge2O7)2] (1), has been grown at high temperature from a KF-MoO3 flux and structurally characterized by single-crystal X-ray diffraction. The pure phase of 1 and the isostructural uranyl-samarium germanate, K4[(UO2)Sm2(Ge2O7)2] (2), have been synthesized by solid state method. Compound 1 is a new 3D framework uranium(VI)–europium(III) germanate. The structure contains PaCl5-type chains of edge-sharing EuO7 pentagonal bipyramids. The structure contains an unusual heterometallic U＝O–Eu linkage. Photoluminescence studies show strong red emission at room temperature. The relative intensity of the 5D0 → 7F1 and 5D0 → 7F2 transitions confirms that the europium site lacks an inversion center. All of the emission lines show similar decay curves, which can be well-fitted by a single exponential decay function with a radiative lifetime of 0.53 ± 0.03 ms. No emission is observed in the region from 450 to 550 nm typical of the uranyl cation, indicating that, upon uranyl excitation, the energy is either transferred to the Eu3+ centers or lost to nonradiative processes. Compound 2 is an isostructural compound. The photoluminescence properties of 2 have also been studied.
Appears in Collections:	[Graduate Institute of Chemistry] Electronic Thesis & Dissertation

Files in This Item:

File	Description	Size	Format
index.html		0Kb	HTML	728	View/Open

社群 sharing

Loading...