The structural transition under compression and correlation between structural and dynamical heterogeneity for liquid Al2O3

This study reported a simulation of structural transition and correlation between structural and dynamical heterogeneity (DH) for liquid Al2O3. Structural characteristics of liquid Al2O3 were clarified through the pair radial distribution functions, the distribution of [Formula: see text] and [Formula: see text] ([Formula: see text], 4, 5, 6; [Formula: see text], 2, 3) basic structural units, angle and bond length distribution and 3D visualization. Simulation results revealed that network structure of liquid Al2O3 is built mainly by AlO3, AlO4, AlO5 and AlO6 units that are linked to each other through common oxygen atoms. We found the existence of separate AlO4-, AlO5- and AlO6-phases where the mobility of atoms can be determined. The atoms in AlO4-phase are more mobile than the ones in AlO5- and AlO6-phases. The existence of separate phases is evidence of DH in liquid Al2O3. Moreover, the self-diffusion of Al and O atoms was also discussed via characteristics of separate AlO4-, AlO5- and AlO6-phases.

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Molecular dynamics simulation for structural heterogeneity and diffusion process in liquid GeO2

Journal of Science Natural Science ◽

10.18173/2354-1059.2021-0005 ◽

2021 ◽

Vol 66 (1) ◽

pp. 42-48

Author(s):

Kien Pham Huu ◽

Linh Nguyen Hong ◽

Hien Pham Xuan ◽

Linh Nguyen Thi Thuy ◽

Quang Phan Dinh ◽

...

Keyword(s):

Diffusion Process ◽

Length Distribution ◽

Structural Heterogeneity ◽

Dynamics Simulation ◽

Angle Distribution ◽

Structural Units ◽

Oxide Systems ◽

Dynamical Heterogeneity ◽

Liquid Oxide ◽

And Diffusion

In this paper, we perform a simulation about liquid GeO2. The structure and diffusion process are analyzed through the radial distribution function, the distribution of GeOx (x = 4, 5, 6) structural units, length distribution, angle distribution, and data visualization. Simulation results show that the structure of liquid GeO2 composes clusters of GeO4, GeO5, or GeO6. These clusters have sizes depending on pressure and are distributed heterogeneously in space. This result confirms the origin of dynamical heterogeneity in the liquid oxide systems. In addition, the diffusion coefficient of Ge and O decreases upon pressure. We show that the diffusion relates to the breaking bond Ge-O.

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Structural properties of liquid aluminosilicate with varying Al2O3/SiO2 ratios: Insight from analysis and visualization of molecular dynamics data

Modern Physics Letters B ◽

10.1142/s0217984917500361 ◽

2017 ◽

Vol 31 (05) ◽

pp. 1750036 ◽

Cited By ~ 4

Author(s):

N. V. Yen ◽

M. T. Lan ◽

L. T. Vinh ◽

N. V. Hong

Keyword(s):

Molecular Dynamics ◽

Random Network ◽

Md Simulations ◽

Degree Of Polymerization ◽

Distribution Functions ◽

Molar Ratio ◽

Nonbridging Oxygen ◽

Structural Units ◽

Self Diffusion ◽

Continuous Random Network

Molecular dynamics (MD) simulations and visualizations were explored to investigate the changes in structure of liquid aluminosilicates. The models were constructed for four compositions with varying Al2O3/SiO2 ratio. The local structure and network topology was analyzed through the pair of radial distribution functions, bond angle, bond length and coordination number distributions. The results showed that the structure of aluminosilicates mainly consists of the basic structural units TO[Formula: see text] (T is Al or Si; y = 3, 4, 5). Two adjacent units TO[Formula: see text] are linked to each other through common oxygen atoms and form continuous random network of basic structural units TO[Formula: see text]. The bond statistics (corner-, edge- and face- sharing) between two adjacent TO[Formula: see text] units are investigated in detail. The self-diffusion coefficients for three atomic types are affected by the degree of polymerization (DOP) of network characterized by the proportions of nonbridging oxygen (NBO) and Q[Formula: see text] species in the system. It was found that Q4 and Q3 tetrahedral species (tetrahedron with four and three bridging oxygens, respectively) decreases, while Q0 (with four nonbridging oxygen) increase with increasing Al2O3/SiO2 molar ratio, suggesting that a less polymerized network was formed. The structural and dynamical heterogeneities, micro-phase separation and liquid–liquid phase transition are also discussed in this work.

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Microstructure of liquid lithium silicate under influence of pressure

10.29007/nljl ◽

2020 ◽

Author(s):

Quynh Truong Duc ◽

Dung Tran Thanh ◽

Van Dung Mai ◽

The Vinh Le

Keyword(s):

Ambient Pressure ◽

Calculated Data ◽

Distribution Functions ◽

Dynamics Simulation ◽

Liquid Lithium ◽

Angular Distributions ◽

Lithium Silicate ◽

Radial Distribution Functions ◽

Microstructural Characteristics ◽

Structural Units

The microstructural characteristics of liquid lithium silicate (Li2SiO3) are investigated by means of molecular dynamics simulation using the Born-Mayer pairwise potentials. The simulations were performed on the systems with up to 2025 atoms (consist of 750 Li, 375 Si, and 1125 O atoms) at 3200K in the 0-30 GPa pressure range. The microstructure of liquid Li2SiO3 is analyzed via pair radial distribution functions (PRDFs), coordination distributions, angular distributions. The results show that the structure of the liquid lithium silicate consists the basic structural units TO4 (T= Li, Si) at ambient pressure, and these units decrease as the pressure increases. Besides, the shape and size of the basic structural units are slightly dependent on pressure. Calculations also indicate that calculated data agree well with the experimental ones.

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Molecular dynamic simulation study of molten cesium

Journal of the Serbian Chemical Society ◽

10.2298/jsc160725018y ◽

2017 ◽

Vol 82 (6) ◽

pp. 681-694 ◽

Cited By ~ 1

Author(s):

Saeid Yeganegi ◽

Vahid Moeini ◽

Zohreh Doroodi

Keyword(s):

Internal Pressure ◽

Diffusion Coefficients ◽

Distribution Functions ◽

Radial Distribution Functions ◽

Coordination Numbers ◽

Self Diffusion ◽

Temperature And Pressure ◽

Molecular Dynamic Simulation Study ◽

Dynamics Simulations ◽

And Diffusion

Molecular dynamics simulations were performed to study thermodynamics and structural properties of expanded caesium fluid. Internal pressure, radial distribution functions (RDFs), coordination numbers and diffusion coefficients have been calculated at temperature range 700?1600 K and pressure range 100?800 bar. We used the internal pressure to predict the metal?non-metal transition occurrence region. RDFs were calculated at wide ranges of temperature and pressure. The coordination numbers decrease and positions of the first peak of RDFs slightly increase as the temperature increases and pressure decreases. The calculated self-diffusion coefficients at various temperatures and pressures show no distinct boundary between Cs metallic fluid and its expanded fluid where it continuously increases with temperature.

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The structural phase-transition pathway under compression and dynamic properties in liquid GeO2

Modern Physics Letters B ◽

10.1142/s0217984920501870 ◽

2020 ◽

Vol 34 (17) ◽

pp. 2050187

Author(s):

P. H. Kien

Keyword(s):

Phase Transition ◽

Structural Phase Transition ◽

3D Visualization ◽

Dynamic Properties ◽

Structural Phase ◽

Three Dimensional ◽

Length Distribution ◽

High Mobility ◽

Dynamical Heterogeneity ◽

Structure Of Liquid

We perform a simulation of the structural phase-transition pathway under compression and dynamic properties in liquid germania (GeO2). The structure of liquid GeO2 is clarified through the pair radial distribution function (PRDF), distribution of GeO[Formula: see text] [Formula: see text] units, bond angle and length distribution, and three-dimensional (3D) visualization. The result shows that the structure of liquid GeO2 is built by GeO4, GeO5 and GeO[Formula: see text]units, which are linked to each other via common oxygen atoms. The GeO[Formula: see text] units lead to form into the separate GeO4-, GeO5- and GeO6-phases. The existence of separate phases is evidence of dynamical heterogeneity (DH) in liquid GeO2. The atoms in GeO5-phase are more mobile compared to other ones. The variation of the self-diffusions of Ge and O atoms under pressure is examined via the characteristics of separate GeO4-, GeO5- and GeO6-phases. We found that under compression, there is diffusion anomaly in liquid GeO2. This is suggested to be related to the very high mobility of Ge and O atoms in the GeO5-phase compared to GeO4- and GeO6-phase.

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Crystallization of amorphous silica under compression

Canadian Journal of Physics ◽

10.1139/cjp-2018-0432 ◽

2019 ◽

Vol 97 (10) ◽

pp. 1133-1139

Author(s):

Nguyen Thu Nhan ◽

Giap Thi Thuy Trang ◽

Toshiaki Iitaka ◽

Nguyen Van Hong

Keyword(s):

Structural Transformation ◽

Amorphous Silica ◽

Pressure Range ◽

Bond Angle ◽

3D Visualization ◽

Structural Phase ◽

Length Distribution ◽

Dynamics Simulation ◽

Structural Phase Transformation ◽

Bond Length Distribution

The structural phase transformation and crystallization of amorphous silica at 500 K under high pressure are investigated by molecular dynamics simulation. Under compression, there is a structural transformation from tetrahedral- to octahedral-network via SiO5 units. Structural transformation occurs strongly in the 5–15 GPa pressure range and there exist three structural phases corresponding to SiO4, SiO5, and SiO6. Beyond 15 GPa, octahedral-network is dominant. At pressure higher than 20 GPa, octahedral network tends to transform to crystalline phase (stishovite). Mechanism of structural transformation is clarified via coordination-number, bond-angle distributions, bond length distribution, and 3D visualization. The size-distribution of phase regions is also determined in this work.

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