The microscopic behavior of the Ca-zeolite yugawaralite has been studied by ab initio molecular dynamics simulations adopting experimental cell parameters obtained at pressures up to similar to9 GPa. Pressure-induced volume contraction occurs via rotations of quasi-rigid TO, tetrahedra that reduce the size of the channels in which the extra-framework species are located. Such rotations are governed by deformation of the coordination polyhedron of Ca, which is made up of water and framework O atoms. Contraction of the Ca-H2O distances is favored at moderate pressure; at higher pressure the shortening of Ca-framework O atom distances becomes prevalent. The hydrogen bond network plays a fundamental role in the overall response to pressure. Our results indicate that the high-P-induced deformation of the framework structure is strictly correlated to the extra-framework species that act as "templates" in the compression process.

The "template" effect of the extra-framework content on zeolite compression: The case of yugawaralite

FOIS, ETTORE SILVESTRO;GAMBA, ALDO;TABACCHI, GLORIA;
2005-01-01

Abstract

The microscopic behavior of the Ca-zeolite yugawaralite has been studied by ab initio molecular dynamics simulations adopting experimental cell parameters obtained at pressures up to similar to9 GPa. Pressure-induced volume contraction occurs via rotations of quasi-rigid TO, tetrahedra that reduce the size of the channels in which the extra-framework species are located. Such rotations are governed by deformation of the coordination polyhedron of Ca, which is made up of water and framework O atoms. Contraction of the Ca-H2O distances is favored at moderate pressure; at higher pressure the shortening of Ca-framework O atom distances becomes prevalent. The hydrogen bond network plays a fundamental role in the overall response to pressure. Our results indicate that the high-P-induced deformation of the framework structure is strictly correlated to the extra-framework species that act as "templates" in the compression process.
2005
zeolites; high-pressure; pressure induced structural modifications; first principles MOLECULAR-DYNAMICS; framework; yugawaralite; water; density functional theory; dft calculations
Fois, ETTORE SILVESTRO; Gamba, Aldo; Tabacchi, Gloria; Arletti, R; Quartieri, S; Vezzalini, G.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11383/1708398
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