Structural Correlations and Mechanical Behavior in Nanophase Silica Glasses

Campbell, Timothy J.; Kalia, Rajiv K.; Nakano, Aiichiro; Shimojo, Fuyuki; Tsuruta, Kenji; Vashishta, Priya; Ogata, Shūji

doi:10.1103/physrevlett.82.4018

Cited by 72 publications

(60 citation statements)

References 13 publications

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“…The model devel-oped by Nakano et al has been successfully employed to describe the bulk and the surface of disordered phases of SiO 2 , viz. amorphous and porous silica, 10,13,[36][37][38][39][40][41] which are evidently relevant to the present problem. In this model, silicon is assumed to be coordinated to four oxygen atoms, that is, the network is chemically ordered.…”

Section: Computational Detailsmentioning

confidence: 88%

“…Our calculations are also in qualitative agreement with MD simulations of pressure-induced densification of silica nanophases, where the height of the FSDP was found to be 15 % smaller compared to a-SiO 2 in the density range 1.67 to 2.03 g/cm 3 . 36 The ring structure of the various models can tell us more about changes in MRO upon densification: because the size of rings is typically in the range 4-10Å, 10 modifications in the MRO are related to those in the arrangements of neighboring Si(O 1/2 ) 4 tetrahedra. The occurrence of the various types of rings as a function of R, relative to R = 0, is shown in Fig.…”

Section: B Structure Of Samples Grown With Bombardmentmentioning

confidence: 99%

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Structural properties of silicon dioxide thin films densified by medium-energy particles

et al. 2001

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Classical molecular-dynamics simulations have been carried out to investigate densification mechanisms in silicon dioxide thin films deposited on an amorphous silica surface, according to a simplified ion-beam assisted deposition (IBAD) scenario. We compare the structures resulting from the deposition of near-thermal (1 eV) SiO2 particles to those obtained with increasing fraction of 30 eV SiO2 particles. Our results show that there is an energy interval -between 12 and 15 eV per condensing SiO2 unit on average -for which the growth leads to a dense, low-stress amorphous structure, in satisfactory agreement with the results of low-energy ion-beam experiments. We also find that the crossover between low-and high-density films is associated with a tensile to compressive stress transition, and a simultaneous healing of structural defects of the a-SiO2 network, namely threeand four-fold rings. It is observed, finally, that densification proceeds through significant changes at intermediate length scales (4-10Å), leaving essentially unchanged the "building blocks" of the network, viz. the Si(O 1/2 )4 tetrahedra. This latter result is in qualitative agreement with the mechanism proposed to explain the irreversible densification of amorphous silica recovered from high pressures (∼ 15-20 GPa).

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Section: Computational Detailsmentioning

confidence: 88%

Section: B Structure Of Samples Grown With Bombardmentmentioning

confidence: 99%

Structural properties of silicon dioxide thin films densified by medium-energy particles

et al. 2001

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“…The nanostructured system was prepared by cutting out spheres of radius 40 A from the well thermalized bulk amorphous system [7]. These spherical nanoparticles were relaxed with the conjugate gradient technique.…”

Section: Computational Proceduresmentioning

confidence: 99%

Dynamic Fracture Mechanisms in Nanostructured and Amorphous Silica Glasses Million-Atom Molecular Dynamics Simulations

et al. 2001

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Parallel molecular dynamics simulations are performed to investigate dynamic fracture in bulk and nanostructured silica glasses at room temperature and 1000 K. In bulk silica the crack front develops multiple branches and nanoscale pores open up ahead of the crack tip. Pores coalesce and then they merge with the advancing crack-front to cause cleavage fracture. The calculated fracture toughness is in good agreement with experiments. In nanostrucutred silica the crack-front meanders along intercluster boundaries, merging with nanoscale pores in these regions to cause intergranular fracture. The failure strain in nanostructured silica is significantly larger than in the bulk systems.

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“…For the bulk modulus of the skeletal frame K B we have used the following relation K B = (1−β) 3.5 K S [10]. Poisson's ratio of the skeletal frame is assumed to be 0.2, thus for the shear modulus of the solid we have N = (3/4)K B .…”

Section: Discussionmentioning

confidence: 99%

“…here we have used (10), (14), (16) and definition (13) as well. From (10) and (14) using (17) we directly get:…”

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confidence: 99%

Theory of sound propagation in superfluid-filled porous media

Buishvili

Kekutia²,

Tkeshelashvili³

et al. 2002

Physics Letters A

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The theory of sound propagation in macroscopically isotropic and homogeneous porous media saturated with superfluid 4 He has been developed neglecting all damping processes. The case when the normal fluid component is locked inside a porous medium by viscous forces is investigated in detail. It is shown that in this case one shear wave and two longitudinal, fast and slow, waves exist. Fast wave as well as slow wave is accompanied with temperature oscillations. The velocities of these waves are obtained.

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Structural Correlations and Mechanical Behavior in Nanophase Silica Glasses

Cited by 72 publications

References 13 publications

Structural properties of silicon dioxide thin films densified by medium-energy particles

Structural properties of silicon dioxide thin films densified by medium-energy particles

Dynamic Fracture Mechanisms in Nanostructured and Amorphous Silica Glasses Million-Atom Molecular Dynamics Simulations

Theory of sound propagation in superfluid-filled porous media

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