The high-pressure behavior of a natural ettringite [Ca6Al2(SO4)3(OH)12·27H2O, a=11.2104(2) Å, c=21.4350(3) Å, sp. gr. P31c] has been studied by single-crystal X-ray diffraction with a diamond-anvil cell up to 4.22 GPa, using the methanol:ethanol=4:1 mixture as a hydrostatic pressure-transmitting fluid. The isothermal bulk modulus (K0=−V(∂P / ∂V)) was found to be 26.6(5) GPa. Ettringite shows a significant anisotropic compressional pattern, being more compressible on (001) than along [001] (i.e. the fibers growing axis), with K(c)0~2K(a,b)0. The mechanisms at the atomic scale, which govern the structure deformation, have been described by a series of structure refinements up to 2.3 GPa. The structure evolution in response to the applied pressure indicates a plausible densification of the hydrogen-bond network between the Ca(OH)4(H2O)4 polyhedra and the SO4 tetrahedra, which results in a softening and ultimately in a collapse of the whole structure at pressures > 3 GPa.

Anisotropic compressional behavior of ettringite / D. Comboni, G.D. Gatta, P. Lotti, M. Merlini, M. Hanfland. - In: CEMENT AND CONCRETE RESEARCH. - ISSN 0008-8846. - 120(2019 Jun), pp. 46-51. [10.1016/j.cemconres.2019.03.012]

Anisotropic compressional behavior of ettringite

D. Comboni
Primo
Writing – Original Draft Preparation
;
G.D. Gatta
Secondo
Writing – Original Draft Preparation
;
P. Lotti
Investigation
;
M. Merlini
Penultimo
Investigation
;
2019

Abstract

The high-pressure behavior of a natural ettringite [Ca6Al2(SO4)3(OH)12·27H2O, a=11.2104(2) Å, c=21.4350(3) Å, sp. gr. P31c] has been studied by single-crystal X-ray diffraction with a diamond-anvil cell up to 4.22 GPa, using the methanol:ethanol=4:1 mixture as a hydrostatic pressure-transmitting fluid. The isothermal bulk modulus (K0=−V(∂P / ∂V)) was found to be 26.6(5) GPa. Ettringite shows a significant anisotropic compressional pattern, being more compressible on (001) than along [001] (i.e. the fibers growing axis), with K(c)0~2K(a,b)0. The mechanisms at the atomic scale, which govern the structure deformation, have been described by a series of structure refinements up to 2.3 GPa. The structure evolution in response to the applied pressure indicates a plausible densification of the hydrogen-bond network between the Ca(OH)4(H2O)4 polyhedra and the SO4 tetrahedra, which results in a softening and ultimately in a collapse of the whole structure at pressures > 3 GPa.
Ettringite; High pressure; Compressibility; Diamond anvil cell; H-bonds
Settore GEO/09 - Georisorse Miner.Appl.Mineral.-Petrogr.per l'amb.e i Beni Cul
Settore GEO/06 - Mineralogia
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/633581
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