Diffusion du silicium dans la silice amorphe

Brebec, G.; Seguin, Remy; Sella, C.; Bevenot, J.; Martin, J.

doi:10.1016/0001-6160(80)90168-6

Cited by 236 publications

(127 citation statements)

References 11 publications

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“…The diffusivities obtained in the present work, which vary from 10 -20 cm 2 /s to 10 -23 cm 2 /s for our range of temperatures, are considerably larger than those reported in previous studies of diffusion under equilibrium or near-equilibrium conditions. 15 However, our results are in much better agreement with self-diffusion studies performed under non-equilibrium conditions. 16 This suggests that a significant reduction of the formation energy of the diffusing species may occur in the present case due to implantation damage, the Si/SiO 2 interface, stresses within the matrix, or other non-equilibrium conditions specific to the nanocrystal/matrix system.…”

supporting

confidence: 88%

Mechanism of stress relaxation in Ge nanocrystals embedded in SiO2

Sharp

et al. 2005

Applied Physics Letters

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Ion-beam-synthesized 74 Ge nanocrystals embedded in an amorphous silica matrix exhibit large compressive stresses in the as-grown state. The compressive stress is determined quantitatively by evaluating the Raman line shift referenced to the line position of freestanding nanocrystals. Post-growth thermal treatments lead to stress reduction. The stress relief process is shown to be governed by the diffusive flux of matrix atoms away from the local nanocrystal growth region. A theoretical model that quantitatively describes this process is presented.

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supporting

confidence: 88%

Mechanism of stress relaxation in Ge nanocrystals embedded in SiO2

Sharp

et al. 2005

Applied Physics Letters

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“…(where k is Boltzmann's constant, T is temperature, ~ is an effective jump distance and t/is viscosity; Glasstone et al, 1941 ) in relating viscosity to 0 and Si diffusivity in silicate liquids (e.g., Brebec et al, 1980;Shimizu and Kushiro, 1984). In this paper, two consequences of structural relaxation on cationic tracer diffusivity are illustrated.…”

Section: Introductionmentioning

confidence: 89%

“…3 are diffusivity data for A1, Fe, Ni and Si in SiO2 glass and for Si in a CaO-A1203-SiO2 melt (Frischat, 1969(Frischat, , 1975Ghoshtagore, 1969;Brebec et al, 1980;Atkinson and Gardner, 1980). The diffusivities of A1, Fe and Ni in SiO2 are removed from the Eyring diffusivity and thus they are predicted to have decreasing diffusivity with decreasing silica content, until their diffusivity approaches the Eyring curve.…”

Section: Observation Time-scale (%)mentioning

confidence: 99%

Effects of structural relaxation on cationic tracer diffusion in silicate melts

Dingwell

1990

Chemical Geology

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Dingwell, D.B., 1990. Effects of structural relaxation on cationic tracer diffusion in silicate melts. Chem. Geol., 82:209-216.The glass transition in silicate melts is a curve in time-temperature space marking the transition of the melt structure from an unrelaxed, disequilibrium glass to a relaxed, equilibrium liquid. Tracer diffusivity data obtained in glasses vs. liquids cannot be compared without consideration of the effects of this transition. For tracer diffusivity experiments, two time scales are important, the time duration of the experiment (~d) and the inverse of the jump frequency (vp) of the tracer.When the time duration of the experiments reaches the relaxation time-scale (~d = rs) of the melt a transition occurs from diffusion in an unrelaxed matrix (undergoing vibrational thermal expansion) to diffusion in a relaxed matrix (undergoing equilibrium, configurational and elastic, thermal expansion). At this transition, an inflection is observed in the temperature dependence of cationic tracer diffusivity. At temperatures below the inflection, the diffusivity is Arrhenian whereas at temperatures above the diffusivity is non-Arrhenian.At high temperatures the tracer diffusivities of the cations approach the value of diffusivity obtained from the Eyring relation ( rp = ~s). The contrasting, high-temperature, composition dependence of Na and Li vs. Co, Cs, Sr, Ba, Eu, Fe and C diffusivities can be explained in terms of the Eyring (network 0 and Si) diffusivity influencing the latter group. The contrasting high-vs. low-temperature, composition dependence of Ba and Sr diffusivities can be similarly explained. These latter observations indicate that all cationic diffusivities will be within a loglo unit of the Eyring oxygen diffusivity in melts with viscosities below 10 P.

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“…8 Horbach and Kob 9 report activation energies of 4.66 eV for oxygen and 5.18 eV for silicon, obtained at temperatures from 2800 to 3250 K. Experiments report activation energies of 6.0 eV for Si, 19 obtained in electrically fused quartz, and 4.7 eV for O, with a much smaller prefactor, 20 obtained in vapor-phase deposited amorphous silica. The large difference in experimental activation energies might be caused by the different sample preparation techniques, resulting in different types of impurities.…”

Section: Energetics and Spatial Extentmentioning

confidence: 98%

Elementary mechanisms governing the dynamics of silica

Mousseau

Barkema

Leeuw

2000

The Journal of Chemical Physics

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A full understanding of glasses requires an accurate atomistic picture of the complex activated processes that constitute the low-temperature dynamics of these materials. To this end, we generate over five thousand activated events in a model silica glass, using the activation-relaxation technique; these atomistic mechanisms are analyzed and classified according to their activation energies, their topological properties and their spatial extent. We find that these are collective processes, involving ten to hundreds of atoms with a continuous range of activation energies; that diffusion and relaxation occurs through the creation, annihilation and motion of single dangling bonds; and that silicon and oxygen have essentially the same diffusivity.

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Diffusion du silicium dans la silice amorphe

Cited by 236 publications

References 11 publications

Mechanism of stress relaxation in Ge nanocrystals embedded in SiO2

Mechanism of stress relaxation in Ge nanocrystals embedded in SiO2

Effects of structural relaxation on cationic tracer diffusion in silicate melts

Elementary mechanisms governing the dynamics of silica

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