Structural changes in the natural zeolite gismondine (GIS) induced by cation exchange with Ag, Cs, Ba, Li, Na, K and Rb
Bauer, Thomas; Baur, Werner H.
European Journal of Mineralogy Volume 10 Number 1 (1998), p. 133 - 148
published: Jan 26, 1998
manuscript accepted: Sep 23, 1997
manuscript received: Mar 8, 1997
ArtNo. ESP147051001013, Price: 29.00 €
Abstract Crystals of the zeolite gismondine, Ca4Al8Si8O32 · 16H2O, were fully ion-exchanged and their crystal structures determined. The Ag- and Cs,Na-gismondines preserved the space group symmetry P21/c of the original natural crystals. The symmetry of Ba-gismondine was reduced to P21. The space group symmetry P21/c changed to / 2/a for Li-, Na- und Rb-gismondine and to / 2 for K-gismondine. Except for Na-gismondine no single crystals were obtained. Therefore, all refinements were performed on powder X-ray diffraction data using the Rietveld powder refinement method. Nonframework cations and H2O molecules were localized in the pores of the frameworks. The aluminosilicate coordination tetrahedra are tilted and the framework is distorted in response to the exchanged cations. Thus a remarkable shrinkage of 13.3% for the cell constant b was observed for Li-gismondine when compared with the original gismondine. The unit cell volume of Ag-gismondine shrank 7.5 % in comparison with gismondine.