The structural correlation and mechanical properties in amorphous hafnium oxide under pressure

2020 ◽  
Vol 34 (22n24) ◽  
pp. 2040149
Author(s):  
Nguyen-Hoang Thoan ◽  
Nguyen-Trung Do ◽  
Nguyen-Ngoc Trung ◽  
Le-Van Vinh
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Atomic Structure ◽  
Hafnium Oxide ◽  
Bond Angle ◽  
Distribution Functions ◽  
Structural Units ◽  
Structural Correlation ◽  
Radical Distribution ◽  
Atomistic Structure

The classical molecular dynamics (MD) technique was used to investigate the atomistic structure of amorphous hafnium oxide (HfO2) under pressure. The local atomic structure and the liquid-solid transition of HfO2 were analyzed for the pair radical distribution functions, bond angle distributions and coordination number. The simulation reveals that although the fractions of structural units HfO[Formula: see text] and OHf[Formula: see text] strongly change with the density, the partial bond angle distributions of these structural units are almost identical for all constructed models. This result has enabled us to establish a relationship between the bond angle distributions and the fractions of structural units.

Molecular Dynamics Simulation of Size Effect on the Mechanical Properties of Amorphous Silica

2015 ◽  
Vol 30 ◽  
pp. 59-67
Author(s):  
Fang Li Duan ◽  
Cheng Zhang ◽  
Qing Song Liu
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Size Effect ◽  
Amorphous Silica ◽  
Bond Angle ◽  
Distribution Functions ◽  
Dynamics Simulation ◽  
Angle Distribution ◽  
Small Model ◽  
Large Model

The frustules of diatoms have excellent elasticity and high strength, but their main composition, amorphous silica, is a kind of typical brittle material. Molecular dynamics simulations of the uniaxial tension were carried out to study the size effect on the mechanical properties of amorphous silica. Stress-strain behavior, the radius of biggest void, radial distribution functions and bond angle distribution were analyzed. Our results show the small model exhibits a better ultimate strength, ductility and toughness than the large model, and the generation and expansion of voids plays an important role in the fracture behavior of the model. For the small model, some of Si-O bonds are stretched, and the average of O-Si-O bond angle decreases from 108o to 95o, which makes the model have a capability to perform larger plastic deformation and lead to a better ductility. However, for the large model, except the change of Si-O-Si bond angle, its structure has no other significant changes. Our results demonstrate that changes of size have significant impact on the mechanical properties and deformation mechanism of intrinsically brittle materials at the nanoscale.

Structure and Properties of the GeAsS Glasses from Ab initio Calculations

2014 ◽  
Vol 1035 ◽  
pp. 502-507
Author(s):  
Li An Chen
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Ab Initio ◽  
Bond Angle ◽  
Distribution Functions ◽  
Dynamics Simulation ◽  
Angle Distribution ◽  
Structure And Properties ◽  
Bond Angle Distribution ◽  
Pair Distribution Functions

The structure and properties of the GexAsxS100-2x have been studied by ab initio molecular dynamics simulation. By calculating the pair distribution functions, bond angle distribution functions, we analyze the structure and properties of the alloys. Calculations show that Ge and As are all well combined with S atoms. When x is smaller than 25.0 the binding increases with x , when x is larger than 25.0 the binding decreases with increasing x . The intervention of As atom does not affect the GeS2 formation in Ge40As40S80

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

2017 ◽  
Vol 31 (05) ◽  
pp. 1750036 ◽  
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.

scholarly journals Study on Cellulose Acetate Butyrate/Plasticizer Systems by Molecular Dynamics Simulation and Experimental Characterization

Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1272
Author(s):  
Weizhe Wang ◽  
Lijie Li ◽  
Shaohua Jin ◽  
Yalun Wang ◽  
Guanchao Lan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Cellulose Acetate ◽  
Distribution Functions ◽  
Binding Energies ◽  
Cellulose Acetate Butyrate ◽  
Dynamics Simulation ◽  
Solubility Parameters ◽  
Acetate Butyrate

Cellulose acetate butyrate (CAB) is a widely used binder in polymer bonded explosives (PBXs). However, the mechanical properties of PBXs bonded with CAB are usually very poor, which makes the charge edges prone to crack. In the current study, seven plasticizers, including bis (2,2-dinitro propyl) formal/acetal (BDNPF/A or A3, which is 1:1 mixture of the two components), azide-terminated glycidyl azide (GAPA), n-butyl-N-(2-nitroxy-ethyl) nitramine (Bu-NENA), ethylene glycol bis(azidoacetate) (EGBAA), diethylene glycol bis(azidoacetate) (DEGBAA), trimethylol nitromethane tris (azidoacetate) (TMNTA) and pentaerythritol tetrakis (azidoacetate) [PETKAA], were studied for the plasticization of CAB. Molecular dynamics simulation was conducted to distinguish the compatibilities between CAB and plasticizers and to predict the mechanical properties of CAB/plasticizer systems. Considering the solubility parameters, binding energies and intermolecular radical distribution functions of these CAB/plasticizer systems comprehensively, we found A3, Bu-NENA, DEGBAA and GAPA are compatible with CAB. The elastic moduli of CAB/plasticizer systems follow the order of CAB/Bu-NENA>CAB/A3>CAB/DEGBAA>CAB/GAPA, and their processing property is in the order of CAB/Bu-NENA>CAB/GAPA>CAB/A3>CAB/DEGBAA. Afterwards, all the systems were characterized by FT-IR, differential scanning calorimetry (DSC), differential thermogravimetric analysis (DTA) and tensile tests. The results suggest A3, GAPA and Bu-NENA are compatible with CAB. The tensile strengths and Young’s moduli of these systems are in the order of CAB/A3>CAB/Bu-NENA>CAB/GAPA, while the strain at break of CAB/Bu-NENA is best, which are consistent with simulation results. Based on these results, it can be concluded that A3, Bu-NENA and GAPA are the most suitable plasticizers for CAB binder in improving mechanical and processing properties. Our work has provided a crucial guidance for the formulation design of PBXs with CAB binder.

Molecular dynamics study on composition and temperature dependences of mechanical properties of CdTeSe nanowires under uniaxial stretching

2019 ◽  
Vol 33 (31) ◽  
pp. 1950373 ◽  
Author(s):  
Bilal Köylüoğlu ◽  
Sholeh Alaei ◽  
Mustafa Kurban
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Separation Distance ◽  
Distribution Functions ◽  
Radial Distribution Functions ◽  
Temperature Dependences ◽  
Pair Separation ◽  
Higher Temperature ◽  
Simulation Results ◽  
Lower Temperature

In this study, a molecular dynamics (MD) study has been performed on composition and temperature dependences of mechanical properties of CdTe[Formula: see text]Se[Formula: see text] ([Formula: see text], 0.50 and 0.75) nanowires with a diameter of 6.93 nm. The simulation results show that CdTe[Formula: see text]Se[Formula: see text] nanowire seems to be more ductile, whereas CdTe[Formula: see text]Se[Formula: see text] nanowire seems to be more brittle at 1 K. Moreover, the temperature and composition exert significant effects on the mechanical properties of CdTeSe nanowires under stretching. We conclude that the dominancy of Se atoms yields a higher stability and strength at the lower temperature of 1 K, whilst it is the same for the nanowires with both higher Te and Se contents at the higher temperature of 300 K. The radial distribution functions (RDFs) have also been calculated for the CdTeSe nanowires based on the pair separation distance at 1 and 300 K.

scholarly journals A reactive molecular dynamics study on the mechanical properties of a recently synthesized amorphous carbon monolayer converted into a nanotube/nanoscroll

2021 ◽  
Author(s):  
Marcelo Lopes Pereira Junior ◽  
Wiliam Ferreira da Cunha ◽  
Douglas Soares Galvão ◽  
Luiz Antonio Ribeiro Junior
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Chemical Vapor Deposition ◽  
Amorphous Carbon ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Free Standing ◽  
Reactive Molecular Dynamics

Recently, laser-assisted chemical vapor deposition has been used to synthesize a free-standing, continuous, and stable monolayer amorphous carbon (MAC).

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