Ag-exchanged analcime: crystal structure and crystal chemistry

• Published in: Microporous and mesoporous materials 2000-09, Vol.39 (1), p.265-273
• Main Authors: Seryotkin, Yu.V, Bakakin, V.V, Belitsky, I.A, Fursenko, B.A
• Format: Article
• Language: English
• Subjects: Ag-analcime; Cation exchange; Crystal chemistry
• ISSN: 1387-1811; 1873-3093
• DOI: 10.1016/S1387-1811(00)00202-X

The crystal structure of Ag-substituted analcime (Ag 1.88[Al 1.88Si 4.12O 12]·2H 2O) prepared by ion exchange of Ag + for Na + was studied by single-crystal X-ray diffraction. The monoclinic unit cell parameters are a=19.369(3) Å, b=13.752(2) Å, c=19.385(2) Å, γ=90.26(1)°, V=5163(1) Å 3, Z=16, space group: F112/ d (No. 15). A comparison was made with the structure of the original Na-analcime. The Ag + cations are located in the vicinity of the former Na positions and octahedrally coordinated (O 4(H 2O) 2). The larger Ag + cations enter the rectangular O 4-windows relatively easily. Only the Ag–OH 2 distances increase significantly. The correlation between the population of extra-framework positions and the Si/Al distribution is significantly better in the Ag-analcime than in the initial Na-analcime. Changes in the unit cell parameters and the symmetry are explained from crystal chemical considerations.