Position of cations and water molecules in hydrated chabazite. Natural and Na-, Ca-, Sr- and K-exchanged chabazites

✍ Scribed by A. Alberti; E. Galli; G. Vezzalini; E. Passaglia; P.F. Zanazzi

• Publisher: Elsevier Science
• Year: 1982
• Tongue: English
• Weight: 584 KB
• Volume: 2
• Category: Article
• ISSN: 0144-2449
• DOI: 10.1016/s0144-2449(82)80075-4

✦ Synopsis

Crystal structures of natural and hydrated Na, Ca, Sr and K-exchanged chabazite from Keller (Germany) were refined at room temperature in the R3m space group. The most probable distribution of ions indicates the presence of four cation sites; one at the centre of the hexagonal prism, two in the large cage along the [111 ] diagonal, and the fourth near the 8-ring window which is split into two sites close to each other in the monovatent exchanged forms. The site at the centre of the D6R is empty in the Na and K-exchanged chabazites.

In this last form one of the two sites along [111] is also empty. Water molecules are spread over a large number of sites, one with 100% occupancy, at the centre of the 8-ring window, the others, normally with low occupancy, inside the large cage. Occupancies of both cation and water molecule sites vary greatly in the different forms.