Reconstructive and displacive transformations of tectosilicates |
| |
Authors: | Dondur V Markovic S Dimitrijevic R Macura S Arandjelovic D |
| |
Institution: | (1) Faculty of Physical Chemistry, St. Trg 12, Belgrade, Yugoslavia;(2) Faculty of Mining and Geology, Department of Crystallography, Djusina 7, Belgrade, Yugoslavia;(3) Department of Biochemistry, Mayo Foundation, Rochester, Minnesota, USA |
| |
Abstract: | By using the thermally induced phase transformation initial zeolites were converted into pure carnegieite, stuffed derivative
of cristobalite. The polymorphs obtained from Na-LTA are stoichiometric (NaAlSiO4), since those obtained from Na-FAU zeolite are non-stoichiometric (Na1-xAl1-xSi1+xO4). Stoichiometric carnegieite have cubic structure, while non-stoichiometric carnegieite crystallized in cubic and orthorhombic
forms. 29Si MAS NMR spectra show a very large but expecting difference between stoichiometric and non-stoichiometric carnegieite. The
spectrum of stoichiometric carnegieite has only one peak Si(4Al), while the spectrum of non-stoichiometric carnegieite consist
few superimposed peaks assigned to Si(4Al), Si(3Al), Si(2Al), Si(1Al) and Si(0Al). DTA study indicates the occurrence of displacive
phase transition of all synthesized carnegieite. The transition temperature is depending on silicon aluminum order: T
m=690°C for stoichiometric, T
m=565 and 660°C for non-stoichiometric, low-temperature and high-temperature carnegieite, respectively.
This revised version was published online in July 2006 with corrections to the Cover Date. |
| |
Keywords: | DTA carnegieite FAU zeolite LTA zeolite |
本文献已被 SpringerLink 等数据库收录! |
|