Polyamorphism of liquid silica under compression based on five order-parameters and two-state model: a completed and unified description

San, L. T.; Hong, Nguyen Van; Hung, P. K.

doi:10.1080/08957959.2016.1151505

Cited by 9 publications

(6 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A smaller Clapeyron slope (dT/dP) above 45 GPa denotes either a smaller volume of fusion (Vm) and/or a higher entropy of fusion (Sm). A higher Sm above 45 GPa is improbable, because we expect large structural similarities between stishovite and HDM, as they both contain most of the Si in a 6-fold coordination (Benmore et al 2010;Lin et al 2007;Meade et al 1992;San et al 2016; Sato and Funamori 2010). Instead, their structural similarities suggest a lower Sm.…”

Section: A Relatively Flat Sio2 Melting Curve From 45 To 90 Gpamentioning

confidence: 98%

“…Polyamorphism in liquid SiO2 has been extensively discussed in the past by theoretical approaches (e.g. (Brazhkin et al 2011;Lin et al 2007;San et al 2016;Takada et al 2016)). To address experimentally the structural evolution of liquid SiO2 under high pressures, we performed LH-DAC experiments coupled with the Soller slits system installed at the ID27 beamline (Weck et al 2013).…”

Section: Analysis Of the Sio2-melt Structure Factorsmentioning

confidence: 99%

See 1 more Smart Citation

Melting behavior of SiO2 up to 120 GPa

et al. 2020

View full text Add to dashboard Cite

The structure of liquid silicates is commonly described as a statistical mixture of various atomic entities with relative abundances that can vary with pressure, temperature and composition. Unfortunately, this view remains largely theoretical due to scarce experimental reports on the silicate melt structure, in particular under pressure. We performed X-ray diffraction of the SiO2 end-member to probe the melting curve up to ~120 GPa and 7000 K, and the melt structure up to ~80 GPa. We confirm the steep increase of the melting curve above ~14 GPa when stishovite becomes stable over coesite in subsolidus conditions, with a slope of about 80 K/GPa. Then, around 45 GPa and 5400 K, the melting curve flattens significantly, an effect most likely reflecting the densification of the SiO2 melt structure. The signal of diffuse X-ray scattering is compatible with a change of the Si coordination number from 4 to 6 along the melting curve, in agreement with previous works reporting a similar evolution during the cold compression of SiO2-glass. Because of the limited pressure range (within 10 to 20 GPa) in which the melting curve changes its slope, we speculate a difficult coexistence of tetrahedral SiO4 and octahedral SiO6 units in SiO2 melt at high pressures.

show abstract

Section: A Relatively Flat Sio2 Melting Curve From 45 To 90 Gpamentioning

confidence: 98%

Section: Analysis Of the Sio2-melt Structure Factorsmentioning

confidence: 99%

Melting behavior of SiO2 up to 120 GPa

et al. 2020

View full text Add to dashboard Cite

show abstract

“…For Si-Si pair, it can be seen that as pressure increases, the location of the first peak of Si-Si pair of RDF shifts to the left and the first peak is splitted into two small peaks at 20, 30 GPa. At low pressure (0, 5 GPa), the Si-Si bond length is 3.10 At high pressure (10,15,20,30 GPa), there are two Si-Si bond lengths, one at about 3.06 and another at about 2.64 Ǻ. Like to Si-O RDF and O-O RDF, Si-Si RDF also has many peaks at pressure 20, 30 GPa.…”

Section: Resultsmentioning

confidence: 99%

“…It accounts for the specific glass-forming properties of SiO2 and for the very low ability of forming crystalline of amorphous silica. The behavior of various high pressure silica phases has been investigated by both theory and experiment for a long time [6][7][8][9][10]. For instance, using the firstprinciples 29 Si NMR analysis, Mauri et al [11] reported that the structural transformations at low-pressure are only accompanied by changes Si-O-Si bond angle without the change in local structure of Si.…”

Section: Introductionmentioning

confidence: 99%

Study of Structure Transition and Crystallization of Amorphous Silica under Compression

Trang¹,

Kien²

2020

MaP

View full text Add to dashboard Cite

In this work, we use molecular dynamic (MD) simulation to study of the structure transition and crystallization of amorphous silica (SiO2) under compression. The structural evolution of amorphous SiO2 is explained through radial distribution function, coordination number distribution, bond angle distribution and visualization. Simulation result shown that there is a structural transformation from tetrahedral to octahedral network through SiO5 units. In the 5-15 GPa pressure range, structural transformation occurs powerfully and there are three structural phases corresponding to SiO4-, SiO5-, and SiO6- ones. At 15 GPa, octahedral-network (SiO6) is dominant. It is the first time we showed that when pressure is higher than 20 GPa, octahedral-network of amorphous SiO2 has a tendency to transform to stishovite crystalline phase.

show abstract

“…Investigating the structure of silica glass is expected to clarify the physical properties and behavior of Si-O network structure [1][2][3][4][5][6][7] under the changes of pressure and temperature. At low pressure, the relatively-rigid SiO 4 tetrahedron is the basic structural unit in silica/silicate glasses and melts: each Si connects to four nearest neighbor O atoms, with Si-O bond length of approximately 1.62 Å, and each O links to two nearest neighbor Si atoms [8][9][10][11]. The Si-O-Si bond angle is very flexible and distributes in a 120-180 • wide-range with the peak at around 144 • which shows the structural differences of silica/silicate glasses in comparison to crystalline forms.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2019

Self Cite

View full text Add to dashboard Cite

The structure of silica glass (SiO2) at different densities and at temperatures of 500 K is investigated by molecular dynamics simulation. Results reveal that at density of 3.317 g/cm 3 , the structure of silica glass mainly comprises two phases: SiO4-and SiO5-phases. With the increase of density, the structure tends to transform from SiO4-phase into SiO6-phase. At density of 3.582 g/cm 3 , the structure comprises three phases: SiO4-, SiO5-, and SiO6-phases, however, the SiO5-phase is dominant. At higher density (3.994 g/cm 3 ), the structure mainly consists of two main phases: SiO5-and SiO6-phases. In the SiO4phase, the SiO4 units mainly link to each other via corner-sharing bonds. In the SiO5-phase, the SiO5 units link to each other via both corner-and edge-sharing bonds. For SiO6-phase, the SiO6 units can link to each other via corner-, edge-, and face-sharing bonds. The SiO4-, SiO5-, and SiO6-phases form SiO4-SiO5-and SiO6-grains respectively and they are not distributed uniformly in model. This results in the polymorphism in the silica glass at high density.

show abstract

Polyamorphism of liquid silica under compression based on five order-parameters and two-state model: a completed and unified description

Cited by 9 publications

References 42 publications

Melting behavior of SiO2 up to 120 GPa

Melting behavior of SiO2 up to 120 GPa

Study of Structure Transition and Crystallization of Amorphous Silica under Compression

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

Contact Info

Product

Resources

About