Syntheses, crystal structures, and ion-exchange properties of porous titanosilicates, HM(3)Ti(4)O(4)(SiO4)(3)center dot 4H(2)O (M=H+, K+, Cs+), structural analogues of the mineral pharmacosiderite
Syntheses, crystal structures, and ion-exchange properties of porous titanosilicates, HM(3)Ti(4)O(4)(SiO4)(3)center dot 4H(2)O (M=H+, K+, Cs+), structural analogues of the mineral pharmacosiderite
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DOI：
10.1021/cm950534c
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发表时间：
1996-06-01
影响因子：
8.6
通讯作者：
Clearfield, A
中科院分区：
文献类型：
--
作者：
Behrens, EA;Poojary, DM;Clearfield, A
钛硅酸盐是矿物药用菱铁矿的结构类似物，以其钾和铯形式制备，并对铯形式进行离子交换以获得酸形式。碱金属阳离子衍生物 HM(3)Ti(4)O(4)(SiO4)(3) .4H2O (M = K+, Cs+) 以及酸形式 H4Ti4O4(SiO4)(3) 。 8H(2)O，与矿物同构。它们在立方空间群中结晶，铯相、钾相和质子相的 a = 7.8212(2) Angstrom、a = 7.7644(3) Angstrom、a = 7.8214(6) Angstrom 和 Z = 1。在该结构中，四个钛八面体在晶胞角周围连接形成Ti4O4立方体，硅酸盐四面体在所有三个晶体方向上连接钛八面体形成三维框架。这些连接形成了充满水分子和可交换离子的三维隧道系统。酸中的电荷中和质子与 Ti4O4 单元中的氧键合。在该组的四个质子中，三个交换铯或钾阳离子，然后剩余的质子将在这四个氧上无序。提出了关于质子相离子交换行为的一些一般观察结果。
Titanosilicate, a structural analogue of the mineral pharmacosiderite, was prepared in its potassium and cesium forms, and the cesium form was ion exchanged to obtain the acid form. The alkali cation derivatives, HM(3)Ti(4)O(4)(SiO4)(3) .4H2O (M = K+, Cs+), as well as the acid form, H4Ti4O4(SiO4)(3) . 8H(2)O, are isostructural with the mineral. They crystallize in the cubic space group with a = 7.8212(2) Angstrom, a = 7.7644(3) Angstrom, a = 7.8214(6) Angstrom, and Z = 1 for the cesium, potassium, and proton phases, respectively. In the structure, four titanium octahedra link to form Ti4O4 cubes around the unit-cell corners, and silicate tetrahedra join the titanium octahedra in all three crystallographic directions to form a three-dimensional framework. These linkages create three-dimensional tunnel systems that are filled by water molecules and exchangeable ions. The charge-neutralizing protons in the acid form bond to the oxygens in the Ti4O4 unit. Among the four protons in this group, three exchange for the cesium or potassium cations and the remaining proton would then be disordered over these four oxygens. Some general observations on the ion-exchange behavior of the proton phase are presented.