The structural transition under densification and the relationship between structure and density of silica glass

Hong, Nguyen Van; Vinh, L.T.; Hung, P. K.; Dung, Mai Van; Yen, N.V.

doi:10.1140/epjb/e2019-100137-7

Cited by 4 publications

(2 citation statements)

References 49 publications

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“…These averaged coordination number of Al-O pair is approximately estimated to be 4.3 ± 0.05. To support experimental methods, simulation is also a powerful method to investigate the microstructure of melts, especially at high-temperature and/or pressure conditions [13][14][15][16][17][18][19]. According to the first-principles molecular dynamic (MD) simulations, Verma et al [8] determined that the liquid Al2O3 is more sensitive to the applied compression than the temperature.…”

Section: Introductionmentioning

confidence: 99%

Characterization of Structural Transition and Heterogeneity under Compression for Liquid Al2O3 Using Molecular Dynamics Simulation

Kien¹,

Nhu²,

Trang³

2022

HighTech. Innov. J.

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We have performed a simulation of the structural transition and Structural Heterogeneity (SH) in liquid Al2O3 at 3500 K, in the range of 0–100 GPa. The results confirmed that the network structure of liquid alumina is built mainly from AlOx (x = 3, 4, 5, 6, 7) units, which are related to each other through the common oxygen atoms. The existence of separate AlO3-, AlO4-, AlO5-, AlO6- and AlO7- phases, where SH of the network structure can be sufficiently determined, besides, the existence of separate phases is clarified for SH in the liquid of Al2O3. In particular, at a pressure below 10 and beyond 20 GPa, AlOx units are uniformly distributed in the space and non-uniformly distributed in the range 10-20 GPa. Our study is expected to contribute to a simple way to determine the structural heterogeneity and diffusion coefficients of oxide systems. Doi: 10.28991/HIJ-2022-03-02-08 Full Text: PDF

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Section: Introductionmentioning

confidence: 99%

Characterization of Structural Transition and Heterogeneity under Compression for Liquid Al2O3 Using Molecular Dynamics Simulation

Kien¹,

Nhu²,

Trang³

2022

HighTech. Innov. J.

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“…[28] The composition and function of different SiO x (x = 4, 5, 6) structures are different in densified silica glass and this variation is often uneven. [29][30][31] Besides, the oxygen hexagonal close-packed (hcp) and facecentered cubic (fcc) clusters were also found in densified silica glass. [32] All these atomic structures are certain to affect the evolution and coalescence of voids.…”

Section: Introductionmentioning

confidence: 99%

Atomistic study on tensile fracture of densified silica glass and its dependence on strain rate*

Hu¹,

Shao²,

Xie³

et al. 2020

Chinese Phys. B

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Densification is a major feature of silica glass that has received widespread attention. This work investigates the fracture behavior of densified silica glass upon uniaxial tension based on atomistic simulations. It is shown that the tensile strength of the silica glass approximately experiences a parabolic reduction with the initial density, while the densified samples show a faster power growth with the increase of strain rate. Meanwhile, the fracture strain and strain energy increase significantly when the densification exceeds a certain threshold, but fracture strain tends to the same value and strain energy becomes closer for different densified samples at extreme high strain rate. Microscopic views indicate that all the cracks are formed by the aggregation of nanoscale voids. The transition from brittleness fracture to ductility fracture can be found with the increase of strain rate, as a few fracture cracks change into a network distribution of many small cracks. Strikingly, for the high densified sample, there appears an evident plastic flow before fracture, which leads to the crack number less than the normal silica glass at the high strain rate. Furthermore, the coordinated silicon analysis suggests that high strain rate tension will especially lead to the transition from 4- to 3-fold Si when the high densified sample is in plastic flow.

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Structural transformation and dynamical heterogeneity in Germania melt under compression: molecular dynamic simulation

et al. 2021

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The structural transformation and dynamical heterogeneity in Germania (GeO2) are investigated via molecular dynamics (MD) simulation. The MD model with 5499 atoms was constructed under pressure up to 150 GPa and at a temperature of 3500 K. The structural transformation mechanism has been studied by observing domain structures and boundary oxygen atoms. The simulation result reveals that GeO2 consists of separate domains and boundaries in its melt structure. Under compression, the structure of GeO2 changes gradually and represents many types of structures. The melt structure exhibits many structural domains Dx, and polymorphism appears at pressures of 12 and 20 GPa. The change of tetrahedral structure to octahedral structure in germanium coordination occurred in parallel with the process of merging and splitting of domain structure. Moreover, the existence of high- and low-density phases in GeO2 melt is indicated. The high-density phase is D6 domain and boundary oxygen while the low-density phase is D4 and D5 domain. The compression mechanism in GeO2 melt mainly is a reduction of average Voronoi volume of oxygen and Voronoi volume of D6, boundary atoms oxygen. Furthermore, we find the dynamical heterogeneity at ambient pressure. The separate “fast” regions and “slow” regions in GeO2 are detected via link-cluster function.

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The structural transition under densification and the relationship between structure and density of silica glass

Cited by 4 publications

References 49 publications

Characterization of Structural Transition and Heterogeneity under Compression for Liquid Al2O3 Using Molecular Dynamics Simulation

Characterization of Structural Transition and Heterogeneity under Compression for Liquid Al2O3 Using Molecular Dynamics Simulation

Atomistic study on tensile fracture of densified silica glass and its dependence on strain rate*

Structural transformation and dynamical heterogeneity in Germania melt under compression: molecular dynamic simulation

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