Reconstructive and displacive transformations of tectosilicates. Non-stoichiometric carnegieite

V. Dondur, S. Markovic, R. Dimitrijevic, S. Macura, D. Arandjelovic

Research output: Contribution to journalArticle

6 Scopus citations

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 (NaAlSiO 4 ), since those obtained from Na-FAU zeolite are non-stoichiometric (Na 1-x Al 1-x Si 1+x O 4 ) Stoichiometric carnegieite have cubic structure, while non-stoichiometric carnegieite crystallized in cubic and orthorhombic forms. 29 Si 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.

Original languageEnglish (US)
Pages (from-to)373-381
Number of pages9
JournalJournal of Thermal Analysis and Calorimetry
Volume72
Issue number1
DOIs
StatePublished - Jan 1 2003

Keywords

  • Carnegieite
  • DTA
  • FAU zeolite
  • LTA zeolite

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Physical and Theoretical Chemistry

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