Syntheses, Crystal Structures, and Ion-Exchange Properties of Porous Titanosilicates, HM3Ti4O4(SiO4)3·4H2O (M = H+, K<
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- 作者：Elizabeth A. Behrens ; Damodara M. Poojary ; and Abraham Clearfield
- 刊名：Chemistry of Materials
- 出版年：1996
- 出版时间：June 1996
- 年：1996
- 卷：8
- 期：6
- 页码：1236 - 1244
- 全文大小：300K
- 年卷期：v.8,no.6(June 1996)
- ISSN：1520-5002
文摘
Titanosilicate, a structural analogue of the mineralpharmacosiderite, was prepared inits potassium and cesium forms, and the cesium form was ion exchangedto obtain the acidform. The alkali cation derivatives,HM3Ti4O4(SiO4)3·4H2O(M = K+, Cs+), as well astheacid form,H4Ti4O4(SiO4)3·8H2O,are isostructural with the mineral. They crystallize inthecubic space group P
3m with a= 7.8212(2) Å, a = 7.7644(3) Å, a= 7.8214(6) Å, and Z = 1for the cesium, potassium, and proton phases, respectively. In thestructure, four titaniumoctahedra link to form Ti4O4 cubes around theunit-cell corners, and silicate tetrahedra jointhe titanium octahedra in all three crystallographic directions to forma three-dimensionalframework. These linkages create three-dimensional tunnel systemsthat are filled by watermolecules and exchangeable ions. The charge-neutralizing protonsin the acid form bond tothe oxygens in the Ti4O4 unit. Among thefour protons in this group, three exchange for thecesium or potassium cations and the remaining proton would then bedisordered over thesefour oxygens. Some general observations on the ion-exchangebehavior of the proton phaseare presented.
3m with a= 7.8212(2) Å, a = 7.7644(3) Å, a= 7.8214(6) Å, and Z = 1for the cesium, potassium, and proton phases, respectively. In thestructure, four titaniumoctahedra link to form Ti4O4 cubes around theunit-cell corners, and silicate tetrahedra jointhe titanium octahedra in all three crystallographic directions to forma three-dimensionalframework. These linkages create three-dimensional tunnel systemsthat are filled by watermolecules and exchangeable ions. The charge-neutralizing protonsin the acid form bond tothe oxygens in the Ti4O4 unit. Among thefour protons in this group, three exchange for thecesium or potassium cations and the remaining proton would then bedisordered over thesefour oxygens. Some general observations on the ion-exchangebehavior of the proton phaseare presented.