School of Environmental Science and Engineering and Department of Chemical Engineering, POSTECH, Pohang, 790-784, Korea.
Dalton Trans. 2010 Mar 7;39(9):2246-53. doi: 10.1039/b920540n. Epub 2010 Jan 12.
The synthetic details of a novel potassium gallosilicate natrolite with Si/Ga = 1.28, denoted PST-1, are described. The presence of K(+) and Ga with well-defined levels of concentration in the synthesis mixture is essential for directing its crystallisation. PST-1 transforms rapidly into TNU-6 under hydrothermal conditions, behaviour that contrasts sharply with its very high thermal and hydrothermal stability, which is unusual for a material of such a high Ga content. These stability issues are discussed and rationalized based on chemical composition, likely violations of Loewenstein's rule and the temperature of dehydration of as-made K-PST-1. The crystal structure of TNU-6 has been resolved through the combined use of synchrotron X-ray and electron diffraction data; it has the BaFeGaO(4) structure type with an additional radical 3a x radical 3a "GeAlO(4)" superstructure that arises from tilting of some of the tetrahedral units in all of the 6-rings.
描述了一种新型钾硅铝酸盐钠沸石，其 Si/Ga = 1.28，记为 PST-1，合成细节。在合成混合物中存在具有明确浓度的 K(+)和 Ga 对于指导其结晶至关重要。PST-1 在水热条件下迅速转化为 TNU-6，这种行为与它非常高的热稳定性和水热稳定性形成鲜明对比，这对于高 Ga 含量的材料来说是不寻常的。这些稳定性问题基于化学成分、可能违反 Loewenstein 规则以及合成的 K-PST-1 的脱水温度进行了讨论和合理化。通过同步加速器 X 射线和电子衍射数据的综合使用，解析了 TNU-6 的晶体结构；它具有 BaFeGaO(4)结构类型，外加一个额外的自由基 3a x 自由基 3a“GeAlO(4)”超结构，这是由于所有 6 元环中的一些四面体单元的倾斜所致。
