高溫高壓水熱法與熔鹽法合成過渡金屬與鑭系金屬矽酸鹽; High-Temperature, High-Pressure Hydrothermal and Flux Synthesis, Crystal Structures and Properties of Transition Metal and Lanthanide Silicates

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题名:	高溫高壓水熱法與熔鹽法合成過渡金屬與鑭系金屬矽酸鹽;High-Temperature, High-Pressure Hydrothermal and Flux Synthesis, Crystal Structures and Properties of Transition Metal and Lanthanide Silicates
作者:	蔡鎮名;Jhen-Ming Tasi
贡献者:	化學研究所
关键词:	金屬矽酸鹽;熔鹽法;高溫高壓水熱法;High-Temperature;High-Pressure Hydrothermal;Flux;Transition Metal Silicates;Lanthanide Silicates
日期:	2008-06-24
上传时间:	2009-09-22 10:19:26 (UTC+8)
出版者:	國立中央大學圖書館
摘要:	本論文利用高溫高壓水熱法及熔鹽法合成兩系列的化合物，第一系列過渡金屬矽酸鹽化合物Rb2(Nb2O4)(Si2O6)．H2O (A1) 、Rb2(Nb2O4)(Si2O6) (A2) 、 Rb2(Ta2O4)(Si2O6)．H2O (A3)；第二系列是鑭系金屬矽酸鹽化合物Rb2YFSi4O10 (B1)、Rb2GdFSi4O10 (B2)、Rb2TbFSi4O10 (B3)、Rb2Tb0.9Eu0.1FSi4O10 (B4)、Rb2Eu0.67Tb0.33FSi4O10 (B5)。這兩系列的化合物利用單晶X光繞射儀定出結構，並以粉末X光繞射圖譜，比對理論圖譜確定樣品純度後再進行物理性質的量測。 A系列中的A1及A3互為等結構化合物，其具有新穎的結構，鈮(鉭)氧多面體以共角的形式連接成二維的層狀結構，再經由以矽氧四面體共角連接而成的[Si4O12]8- 四員環單元，以共角的形式連接，進而形成三維的骨架結構。將A1加熱至500 oC，留停一小時，可將孔洞內水分子移除可得A2，且降回室溫後，停留數小時，待水分子重新吸附回孔洞中，結構再次轉變回A1，此為一可逆的吸附行為，我們更進一步將化合物A2加熱至900 oC，發現結構仍穩定存在，顯示其熱穩定很高。 B系列中的所有化合物皆為等結構化合物，金屬氧多面體共角連接形成無限延伸鏈，而鏈與鏈之間則是經由以矽酸鹽四面體共角連接所組成的鋸齒鏈來連接形成一個新穎的三維結構。在本研究中，針對此系列化合物之中心金屬的發光特性，進行放光光譜的研究與探討，並合成混金屬化合物B4、B5，以探討金屬離子間能量轉移的現象。 Two series of transition metal and lanthanide silicates. Three metal silicates were synthesized by the high-temperature, high-pressure hydrothermal method. The series A denotes transition metals silicates, Rb2(Nb2O4)(Si2O6)·H2O (A1), Rb2(Nb2O4)(Si2O6) (A2) and Rb2(Ta2O4)(Si2O6)．H2O (A3). Five metal silicates were synthesized by the flux-growth method. The series B denotes lanthanide silicates, Rb2YFSi4O10 (B1), Rb2GdFSi4O10 (B2), Rb2TbFSi4O10 (B3), Rb2Tb0.9Eu0.1FSi4O10 (B4) and Rb2Eu0.67Tb0.33FSi4O10 (B5). All structures of those compounds are determined by single-crystal X-ray diffraction. The purity of each compound was confirmed by the good agreement between observed powder X-ray pattern and the calculated pattern based on single-crystal X-ray diffraction. The properties of these compounds were further characterized by different physical measurements respectively according to their structural features : the dehydration of A1 by thermogravimetric analysis (TGA) and the luminescence spectra of lanthanide silicates. A1 and A3 are isostructural, representing a novel structure. Upon heating to 500 oC, A1 loses the lattice water molecules, while the framework structure retains to give the anhydrous compound A2. If A2 is exposed to air for several hours, the water molecules can be restored based on powder X-ray diffraction, and structure will be changed into A1. All compounds of series B have similar structures, representing a novel structure. These materials have been characterized by photoluminescence spectroscopy, including emission and excitation spectra. Mixed lanthanide samples B4 and B5 have also been prepared and efficient Tb →Eu energy transfer has been observed for B4.
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