The thermodynamics of water and hydrogen solubility in fused silica

Shackelford, James F.; Masaryk, Joseph S.

doi:10.1016/0022-3093(76)90091-0

Cited by 32 publications

(18 citation statements)

References 6 publications

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“…(2) and not the diffusion coefficient that controls the outflow of molecular hydrogen (Morimoto et al 1992). This is supported by the activation energy of the reaction which lies between 260 kJ mol −1 (Heslin 1993) and 266 kJ mol −1 (van der Steen 1976) and which compares well with the binding energy of the SiO-H bond (264 kJ mol −1 , Shackelford & Masaryk 1976). It is thus the breaking of this bond that controls the dehydrogenation of the silicate.…”

Section: Discussionsupporting

confidence: 57%

Laboratory investigation of crystallisation in annealed amorphous MgSiO$\mathsf{_{3}}$

Thompson

Tang

2001

A&A

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Abstract. In situ high resolution synchrotron X-ray powder diffraction measurements are used to probe the structural changes in a sample of amorphous MgSiO3 during annealing. Temperatures cover the astrophysically significant range 1000 K to 1173 K and prior to annealing the sample showed typical amorphous structure. Following ∼2 hours annealing at 1000 K an initial crystallite had formed that was coexistent with a modified amorphous component. Increases in temperature coupled with long annealing times produced no further change to the amorphous component and only very minor changes in the appearance of the crystalline phase. This we identify as a structural stall in the crystallisation process and is likely to be the origin of the spectral stall reported for similar silicate materials. Finally at 1173 K, following a cumulative annealing time of ∼79 hours, the amorphous background began to collapse coinciding with the development of further crystalline features. The stall in structural development arises because the crystallisation process is in part regulated by the amorphous phase during annealing. At low-end temperatures it is likely that the annealing process itself strengthens the amorphous phase allowing it to survive up to relatively high temperatures. This finding suggests that some lower temperature information may be preserved in certain cosmic dust grains that were initially annealed at lower temperatures.

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Section: Discussionsupporting

confidence: 57%

Laboratory investigation of crystallisation in annealed amorphous MgSiO$\mathsf{_{3}}$

Thompson

Tang

2001

A&A

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“…For 1000°C the data sets reported in Refs. [11,12] are very similar. Therefore, a comparison was only made with one of these data sets [11].…”

Section: Water Uptakementioning

confidence: 69%

“…(4) Code 1737 glass annealed in moist air at 650, 700 and 800°C, respectively. 2 For the water solubility in silica glass one can find some data from the literature [11,12] which can be compared with the estimated values given above. For 1000°C the data sets reported in Refs.…”

Section: Water Uptakementioning

confidence: 98%

Incorporation of water into glasses and its influence on the diffusion of cations, including the creation of diffusion barriers

Tian

Dieckmann

2006

Journal of Non-Crystalline Solids

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“…(van der Steen 1976) and compares well with the binding energy of the SiO-H bond (264 kJ mol −1 , Shackelford & Masaryk 1976). It is thus the breaking of this bond that should control the dehydrogenation of the silicate.…”

Section: X-ray Diffractionmentioning

confidence: 86%

Laboratory study of annealed amorphous MgSiO$_{\sf 3}$ silicate using IR spectroscopy and synchrotron X-ray diffraction

Thompson

Fonti

Verrienti

et al. 2002

A&A

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Abstract. We present the results of combining in situ high resolution synchrotron X-ray powder diffraction and infrared spectroscopic measurements on an amorphous pyroxene powder sample annealed in the region of 1000 K. We find using both techniques that the crystalline structure formed during annealing is Mg 2 SiO 4 (forsterite), but that the presence of certain features in the 10 µm band normally attributed to crystalline enstatite (MgSiO 3 ) is contradicted by spectroscopy in the 20 µm region (along with certain other 10 µm band features) and X-ray diffraction. Both indicate crystalline forsterite as the only crystalline phase formed at this temperature. We discuss the possible mechanism of forsterite formation from amorphous pyroxene and identify the presence of proto-forsteritic structures in the amorphous starting material. We suggest the likely origin of the 10 µm band "crystalline enstatite" features as being due to short-range improvements in the amorphous MgSiO 3 network ordering which are not necessarily accompanied by the formation of crystalline enstatite structure. These results not only suggest that the formation of crystalline enstatite dust grains via annealing may be difficult to realise at this temperature, but also highlight the possibility, in the absence of additional corroborating evidence, of misidentifying the nature of the carrier of the 10 µm "enstatite" features when observed in the spectra of objects such as comets. We also discuss the evolution of fine structure in the region of 15 to 16 µm, which may serve as an observational indicator of grain processing in stellar sources.

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The thermodynamics of water and hydrogen solubility in fused silica

Cited by 32 publications

References 6 publications

Laboratory investigation of crystallisation in annealed amorphous MgSiO$\mathsf{_{3}}$

Laboratory investigation of crystallisation in annealed amorphous MgSiO$\mathsf{_{3}}$

Incorporation of water into glasses and its influence on the diffusion of cations, including the creation of diffusion barriers

Laboratory study of annealed amorphous MgSiO$_{\sf 3}$ silicate using IR spectroscopy and synchrotron X-ray diffraction

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