排序方式: 共有1条查询结果,搜索用时 31 毫秒
1
1.
Dondur V. Markovic S. Dimitrijevic R. Macura S. Arandjelovic D. 《Journal of Thermal Analysis and Calorimetry》2003,72(1):373-381
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. 相似文献
1