Crystallization of a basic sodalite under hydrothermal conditions studied by MAS-NMR, XRD and DTA/DTG
Mundus, Carsten; Müller-Warmuth, Werner; Buhl, Josef-Christian
European Journal of Mineralogy Volume 8 Number 2 (1996), p. 231 - 240
published: Apr 26, 1996
manuscript accepted: Nov 20, 1995
manuscript received: Jun 16, 1995
ArtNo. ESP147050802009, Price: 29.00 €
Abstract Hydrothermal syntheses in the system Na2O-SiO2-Al2O3-H2O, using cristobalite, corundum and mullite as starting substances, show simultaneous crystallization of basic hydrosodalite with basic cancrinite. The samples are characterized relative to their composition and the structure of the resulting products by 29Si and 27Al MAS-NMR spectroscopy in combination with thermal analysis and powder X-ray diffraction. By extending the reaction times up to 240 h, two different mechanisms could be identified at 423 and 473 K: at elevated temperature, the formation of cancrinite starts earlier and the reaction rate is increased. In both cases, crystallization of the products is accompanied by a transformation of the cancrinite into sodalite.