Nanoporous Intergrowths: How Crystal Growth Dictates Phase Composition and Hierarchical Structure in the CHA/AEI System
Some of the most important nanoporous materials that are used for industrial applications are formed as intergrowths between structurally related phases. Further, the specific properties and functions are often strongly related to the nature of these intergrowths. By their nature such structures are notoriously difficult to characterize in detail and thereby formulate a structure/property relationship. We approach the problem of the industrially relevant CHA/AEI intergrowth system by getting insight into not only the structure of the materials but also the crystal-growth mechanism and show that the former is crucially dependent upon the latter. Through a detailed X-ray diffraction analysis with optimization of the CHA/AEI layer stacking sequence, it is shown that up to three distinct components are present. These consist of the two end member structures intimately cocrystallizing with an intergrowth structure. The intergrowth composition is further corroborated by nuclear magnetic resonance and unit cell ...