金屬鍺酸鹽之合成、結構鑑定與性質探討

Synthesis, Crystal Structures and Properties of Metal Germanates

陳佩琳(Pei-Lin Chen)

指導教授 ： 李光華

國立中央大學/理學院/化學系/碩士(2007年)

摘要

本論文研究利用高溫高壓水熱法合成兩系列的化合物，第一系列是鑭系金屬鍺酸鹽化合物K3Eu3Ge6O18 (A1) 及K3Tb3Ge6O18 (A2)；第二系列是錫鍺酸鹽化合物Na4Sn2Ge5O16•H2O (B1) 及 Na4Sn2Ge5O16•xH2O (B2)。這兩系列的化合物皆利用單晶X光繞射決定出結構及化學式，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所需物理性質的測量。在本研究中針對不同化合物的特性進行測量：鑭系金屬化合物的磁性現象及放光光譜、化合物B1 之熱重分析觀察脫水過程等。
A系列的兩個化合物互為等結構化合物，其具有新穎的結構，銪(鋱)氧多面體以共邊的形式連接成一維的Z型鏈，再利用鍺氧四面體以共角連接而成的[Ge3O9]6-三員環，以共邊及共角的形式連接相鄰的Z型鏈，進而形成三維的骨架結構。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，並對研究結果作進一步的探討。
B系列的兩個化合物具類似結構，鍺氧四面體共角連接形成[Ge5O16]12-五聚體鏈，再利用錫氧八面體以共角形式將其連接起來，形成三維的骨架結構，將化合物B1加熱其結構會產生轉變，當加熱至700 ℃，除去部份結晶水時，會轉變成化合物 B2，而加熱至900 ℃時，除去全部的結晶水，會轉變成實驗室先前利用助熔劑法合成出的一個具有新穎結構的化合物Na4Sn2Ge5O16。

關鍵字

金屬鍺酸鹽

並列摘要

Four metal germanates were synthesized by the high-temperature, high pressure hydrothermal method, and the compounds are classified into two series based on their metal centers. The series A denotes lanthanide germanates, K3Eu3Ge6O18 (A1) and K3Tb3Ge6O18 (A2), while the series B denotes tin germanates, Na4Sn2Ge5O16•H2O (B1) and Na4Sn2Ge5O16•xH2O (B1). All structures of these compounds are determined by single-crystal X-ray diffraction (XRD). The purity of each compound was confirmed by the good agreement between the observed powder X-ray differcation pattern and the calculated pattern based on single-crystal XRD. The properties of these compounds were further characterized by different physical measurements respectively according to their structural features: the magnetic behavior and luminescence spectra of lanthanide germanates, and the dehydration of B1 by thermogravimetric analysis (TGA).
A1 and A2 are isostructural, representing a novel structure. The structure contain parallel zigzag chains of edge-sharing Eu(Tb)-O polyhedra, which are in turn linked by sharing vertices and edges with three-membered single ring [Ge3O9]6- germanate anions to form a 3-D framework structure. The luminescence spectra were successfully recorded and the results will be discussed.
Both compounds of series B have similar structures. These compounds contain [Ge5O16]12- fivefold germanate tetrahedra, which are in turn linked by SnO6 octahedra to form 3-D framework structures. The structure of B1 will change into B2 via heating. B1 will convert into B2 when it is heated to 700℃ for removing a part of lattice water. Furthermore B1 will change into a new compound, Na4Sn2Ge5O16, when heated to 900℃ for removing all lattice water molecules, which has been synthesized by the flux-growth method.

並列關鍵字

Metal Germanates

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