Thermal behaviour of siliceous faujasite: Further structural interpretation of negative thermal expansion
Articolo
Data di Pubblicazione:
2015
Abstract:
The high-temperature behaviour of siliceous faujasite (Si-Y) was investigated by in situ synchrotron X-ray powder diffraction from room temperature up to 1123 K. This porous phase is remarkably stable when heated, and no phase transitions or changes in symmetry are observed. A marked negative thermal expansion (NTE), already reported in literature for a heating range from 25 to 573 K, was confirmed up to about 923 K. Above this temperature a positive thermal expansion was observed. Si-Y’s thermal behaviour was interpreted on the basis of the transverse thermal vibrations of the oxygen atoms involved in the T–O–T linkages and a series of other structural features characterizing the faujasite structure, namely the T-T distances between adjacent tetrahedral sites, the thickness of the double 6-membered rings, and the ditrigonal index of the 6-membered rings. Moreover, the thermal behaviour of several other anhydrous porous materials with NTE behaviour is discussed and compared to that of Si-Y.
Tipologia CRIS:
03A-Articolo su Rivista
Keywords:
Siliceous faujasite, Thermal behaviour, NTE, In situ time-resolved X-ray powder diffraction, Rietveld refinement
Elenco autori:
Lara Leardini;Simona Quartieri;Giovanna Vezzalini;Rossella Arletti
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