Characterization of heterogeneities in new-generation synthetic quartz crystals by small-angle X-ray scattering

Guzzo, Pedro L.; Pasquali, Matteo; Gusken, Edmilton; Suzuki, Carlos K.; Azevêdo, W.M. de; Mikawa, Y.

doi:10.1107/s0021889803001791

Cited by 2 publications

(2 citation statements)

References 16 publications

(19 reference statements)

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“…11 As a result, water defects in quartz have been studied extensively, both by computational and experimental investigations. [12][13][14][15][16][17][18][19][20][21] Many geochemical processes, for example soil solution chemistry in natural water, involve the formation and dissolution of the solid phase, 22-24 which largely depends on the molecular interaction of surface species with those in the aqueous matrix. Thus, the interaction of water with the quartz surface has also been the a to calculate the energies of their hydration and dissolution at a liquid/water interface.…”

Section: Introductionmentioning

confidence: 99%

Molecular dynamics simulations of hydration, dissolution and nucleation processes at the α-quartz (0001) surface in liquid water

Leeuw

2006

Dalton Trans.

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Molecular dynamics simulations have been employed to investigate the hydration and dissolution of alpha-quartz (0001) surfaces in a liquid water environment. Our study indicates that the structure of the water layers near the surfaces is affected by the nature of the substrate surface and by temperature. Ordered mono-layers of interfacial water molecules form in the region of the substrate where the surface is highly charged and built up of Si-O-Si bridges. As the temperature is increased this ordered mono-layer structure is gradually lost. When the surface is terminated by silanol groups, the water retains liquid-like properties even at low temperature and the molecules are distributed in a random manner, without the formation of distinct ordered mono-layers of water molecules near the surface. Taking into account the entropy of the system, the calculated energies of stepwise dissolution of a silicon species from the surface suggest that on thermodynamic grounds the complete dissolution of silicon atoms from the quartz surfaces in a liquid water environment is an endothermic process, but that the formation of a -Si(OH)3 species at the surface would be possible. In addition, if the Si(OH)(4) species were to be dissolved, it would remain near the surface, and re-deposition at the defect-free surface is thermodynamically preferred, although there is an activation enthalpy to the first step in the process of nucleation of Si(OH)4 at the perfect surface.

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Section: Introductionmentioning

confidence: 99%

Molecular dynamics simulations of hydration, dissolution and nucleation processes at the α-quartz (0001) surface in liquid water

Leeuw

2006

Dalton Trans.

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“…In previous work, the clustering of water aggregates was investigated in samples from typical growth sectors of a Z-plate synthetic quartz, coupling small-angle X-ray scattering (SAXS) and infrared spectroscopy (IRS) (Guzzo et al, 2003). As a result, no clear relationship was observed between the OH content and the radius of water aggregates calculated from the scattering curves.…”

Section: Introductionmentioning

confidence: 99%

Two-dimensional small-angle X-ray scattering from as-grown and heat-treated synthetic quartz

et al. 2007

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The small-angle X-ray scattering (SAXS) in as-grown and heat-treated quartz crystals was investigated as a function of the azimuth angle around the primary beam. For this, samples parallel to (10 1 10) were extracted from Z-and ÀX-growth sectors of a synthetic quartz bar which had the OH content evaluated by infrared spectroscopy (IRS). In addition, SAXS and IRS were independently recorded as a function of heating temperature. As a result, the two-dimensional SAXS images revealed an anisotropic pattern randomly decorated by lowintensity Kossel lines. The intensities were projected along specific directions or were axially integrated around the primary beam. It was observed that the Porod invariant (Q) increased and the Kossel lines moved slightly to higher q values with increasing temperature. The effect of the sample orientation on the Q value and the lack of a clear relationship between Q and OH content suggested that the diffuse scattering due to the periodicity of the crystal lattice played an important role in the small-angle scattering of quartz. The net scattering intensities produced by heat-treatment at 873 K were attributed to molecular water aggregates created by the diffusion of as-grown OH defects.

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Characterization of heterogeneities in new-generation synthetic quartz crystals by small-angle X-ray scattering

Cited by 2 publications

References 16 publications

Molecular dynamics simulations of hydration, dissolution and nucleation processes at the α-quartz (0001) surface in liquid water

Molecular dynamics simulations of hydration, dissolution and nucleation processes at the α-quartz (0001) surface in liquid water

Two-dimensional small-angle X-ray scattering from as-grown and heat-treated synthetic quartz

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