Does porous mean soft? On the elastic behaviour and structural evolution of zeolites under pressure
Articolo
Data di Pubblicazione:
2008
Citazione:
Does porous mean soft? On the elastic behaviour and structural evolution of zeolites under pressure / G.D. Gatta. - In: ZEITSCHRIFT FUR KRISTALLOGRAPHIE. - ISSN 0044-2968. - 223:1-2(2008), pp. 160-170.
Abstract:
This is a comparative study on lattice compressibility,
pressure (P)-induced structural deformation
mechanisms and influence of the framework and extra-framework
content on the elastic behaviour of zeolites, based
on previously published data obtained by in situ HP-single
crystal and powder diffraction experiments. The elastic
data of zeolites reported so far allow us to infer that: 1)
the peculiar characteristics of the zeolitic structure, with
large channels and a flexible framework built of rigid
units (i.e. the tetrahedra), implies that the main deformation
mechanisms at high-pressure (HP) are controlled by
rigid (Si,Al)O4-tetrahedral tilting; 2) the structural rearrangement
at HP is mainly driven by framework geometry
and its topological symmetry; 3) the compressibility of
zeolites appears not to be directly related to the microporosity,
represented by the “framework density”; 4) the elastic
parameters available for natural zeolites demonstrate
that microporosity does not necessarily imply high compressibility.
Several zeolites appear to be less compressible
than many rock-forming minerals. A high compressibility
is generally expected for open-framework structures due to
the tetrahedral tilting, which produces inter-tetrahedral angle
variations and accommodates the effect of pressure.
However, the bonding between the host zeolitic framework
and the stuffed guest species (cations and H2O molecules)
affect the overall compression behaviour, making this class
of porous material unexpectedly less compressible than
other silicates.
Tipologia IRIS:
01 - Articolo su periodico
Keywords:
zeolites ; compressibility
Elenco autori:
G.D. Gatta
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