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Special Issue "Computational Multiscale Modeling and Simulation in Materials Science"

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Structure Analysis and Characterization".

Deadline for manuscript submissions: closed (31 December 2016)

Special Issue Editor

Guest Editor
Dr. Martin O. Steinhauser

Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
Website | E-Mail
Interests: multiscale modeling and simulation of biological and soft matter systems; cancer research; multi-scale characterization of materials; image-based analysis; composite materials; shock wave physics; coarse-grained modeling; polymer physics; method development and high-performance computing

Special Issue Information

Dear Colleagues,

Computational modeling of materials on multiscales, along with high-performance computer simulations, are gradually becoming reliable tools for scientific investigations in materials science, complementing traditional experimental engineering approaches of macroscopic constitutive descriptions of materials and their optimization in elaborate trial and error experiments. The linkage between material microstructure and materials properties is at the heart of all materials modeling. Multiscale modeling approaches are required to make this link from the electronic and atomic structure of matter and discrete structural defects to the continuum descriptions appropriate at larger scales.

Although the field of Computational Multiscale Modeling is very much still under development, modern Multiscale Materials Modeling techniques are clearly demonstrating the ability to solve computational materials problems with unprecedented levels of rigor and accuracy and to provide powerful new tools for materials design.

By its very nature, Computational Multiscale Modeling is a very interdisciplinary research field with useful contributions from physics, chemistry, materials science, and biology, as well as computer science, mathematics, and mechanics. Consequently, this Special Issue will address all research areas pertaining to the general theme of linking structural features on various length or time scales with material properties, which includes:

  1. Polymer Physics, Modeling of Biological and Soft Materials.
  2. Crystalline and Granular Structures in Metals, Glasses or Ceramic Materials.
  3. Modeling of Multifunctional or Composite Materials.
  4. Micromechanics and Microstructure Modeling.
  5. Statistical Approaches.
  6. Material Behavior under Shock and Impact.
  7. Scale-Bridging Atomistic and Coarse-Grained Approaches.
  8. Particle-Based, Meshfree Method Development.

Dr. rer. nat. Martin O. Steinhauser
Guest Editor

Manuscript Submission Information

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Keywords

  • multiscale modeling
  • shock and impact
  • biological and soft materials
  • microstructures
  • molecular dynamics simulations
  • atomistic simulations
  • coarse-graining
  • ab initio methods
  • meshfree particle methods
  • high-performance scientific computing

Published Papers (23 papers)

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Open AccessArticle A Novel Silicon Allotrope in the Monoclinic Phase
Materials 2017, 10(4), 441; doi:10.3390/ma10040441
Received: 1 March 2017 / Revised: 10 April 2017 / Accepted: 18 April 2017 / Published: 22 April 2017
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Abstract
This paper describes a new silicon allotrope in the P2/m space group found by first-principles calculations using the Cambridge Serial Total Energy Package (CASTEP) plane-wave code. The examined P2/m-Si belongs to the monoclinic crystal system. P2/m
[...] Read more.
This paper describes a new silicon allotrope in the P2/m space group found by first-principles calculations using the Cambridge Serial Total Energy Package (CASTEP) plane-wave code. The examined P2/m-Si belongs to the monoclinic crystal system. P2/m-Si is an indirect band-gap semiconductor with a band gap of 1.51 eV, as determined using the HSE06 hybrid functional. The elastic constants, phonon spectra and enthalpy indicate that P2/m-Si is mechanically, dynamically, and thermodynamically stable. P2/m-Si is a low-density (2.19 g/cm3) silicon allotrope. The value of B/G is less than 1.75, which indicates that the new allotrope is brittle. It is shown that the difference in the elastic anisotropy along different orientations is greater than that in other phases. Finally, to understand the thermodynamic properties of P2/m-Si, the thermal expansion coefficient α, the Debye temperature ΘD, and the heat capacities CP and CV are also investigated in detail. Full article
(This article belongs to the Special Issue Computational Multiscale Modeling and Simulation in Materials Science)
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Open AccessFeature PaperArticle Discrete Particle Method for Simulating Hypervelocity Impact Phenomena
Materials 2017, 10(4), 379; doi:10.3390/ma10040379
Received: 21 December 2016 / Revised: 28 March 2017 / Accepted: 30 March 2017 / Published: 2 April 2017
Cited by 1 | PDF Full-text (16452 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
In this paper, we introduce a computational model for the simulation of hypervelocity impact (HVI) phenomena which is based on the Discrete Element Method (DEM). Our paper constitutes the first application of DEM to the modeling and simulating of impact events for velocities
[...] Read more.
In this paper, we introduce a computational model for the simulation of hypervelocity impact (HVI) phenomena which is based on the Discrete Element Method (DEM). Our paper constitutes the first application of DEM to the modeling and simulating of impact events for velocities beyond 5 kms-1. We present here the results of a systematic numerical study on HVI of solids. For modeling the solids, we use discrete spherical particles that interact with each other via potentials. In our numerical investigations we are particularly interested in the dynamics of material fragmentation upon impact. We model a typical HVI experiment configuration where a sphere strikes a thin plate and investigate the properties of the resulting debris cloud. We provide a quantitative computational analysis of the resulting debris cloud caused by impact and a comprehensive parameter study by varying key parameters of our model. We compare our findings from the simulations with recent HVI experiments performed at our institute. Our findings are that the DEM method leads to very stable, energy–conserving simulations of HVI scenarios that map the experimental setup where a sphere strikes a thin plate at hypervelocity speed. Our chosen interaction model works particularly well in the velocity range where the local stresses caused by impact shock waves markedly exceed the ultimate material strength. Full article
(This article belongs to the Special Issue Computational Multiscale Modeling and Simulation in Materials Science)
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Open AccessArticle Deformation Modes and Anisotropy of Anti-Perovskite Ti3AN (A = Al, In and Tl) from First-Principle Calculations
Materials 2017, 10(4), 362; doi:10.3390/ma10040362
Received: 27 February 2017 / Revised: 19 March 2017 / Accepted: 25 March 2017 / Published: 29 March 2017
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Abstract
Deformation modes were studied for Ti3AN (A = Al, In and Tl) by applying strain to the materials using first-principle calculations. The states of the bonds changed during the deformation process, and the Ti-N bonds remained structurally stable under deformation. The
[...] Read more.
Deformation modes were studied for Ti3AN (A = Al, In and Tl) by applying strain to the materials using first-principle calculations. The states of the bonds changed during the deformation process, and the Ti-N bonds remained structurally stable under deformation. The elastic anisotropy, electronic structures, hardness, and minimum thermal conductivity of anti-perovskite Ti3AN were investigated using the pseudo potential plane-wave method based on density functional theory. We found that the anisotropy of Ti3InN was significantly larger than that of Ti3AlN and Ti3TlN. All three compounds were mechanically stable. The band structures of the three compounds revealed that they were conductors. The minimum thermal conductivities at high temperature in the propagation directions of [100], [110], and [111] were calculated by the acoustic wave velocity, which indicated that the thermal conductivity was also anisotropic. It is indicated that Ti3InN is a good thermal barrier material. Full article
(This article belongs to the Special Issue Computational Multiscale Modeling and Simulation in Materials Science)
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Open AccessArticle The Role of Geometrically Necessary Dislocations in Cantilever Beam Bending Experiments of Single Crystals
Materials 2017, 10(3), 289; doi:10.3390/ma10030289
Received: 25 January 2017 / Revised: 1 March 2017 / Accepted: 3 March 2017 / Published: 16 March 2017
Cited by 1 | PDF Full-text (6410 KB) | HTML Full-text | XML Full-text
Abstract
The mechanical behavior of single crystalline, micro-sized copper is investigated in the context of cantilever beam bending experiments. Particular focus is on the role of geometrically necessary dislocations (GNDs) during bending-dominated load conditions and their impact on the characteristic bending size effect. Three
[...] Read more.
The mechanical behavior of single crystalline, micro-sized copper is investigated in the context of cantilever beam bending experiments. Particular focus is on the role of geometrically necessary dislocations (GNDs) during bending-dominated load conditions and their impact on the characteristic bending size effect. Three different sample sizes are considered in this work with main variation in thickness. A gradient extended crystal plasticity model is presented and applied in a three-dimensional finite-element (FE) framework considering slip system-based edge and screw components of the dislocation density vector. The underlying mathematical model contains non-standard evolution equations for GNDs, crystal-specific interaction relations, and higher-order boundary conditions. Moreover, two element formulations are examined and compared with respect to size-independent as well as size-dependent bending behavior. The first formulation is based on a linear interpolation of the displacement and the GND density field together with a full integration scheme whereas the second is based on a mixed interpolation scheme. While the GND density fields are treated equivalently, the displacement field is interpolated quadratically in combination with a reduced integration scheme. Computational results indicate that GND storage in small cantilever beams strongly influences the evolution of statistically stored dislocations (SSDs) and, hence, the distribution of the total dislocation density. As a particular example, the mechanical bending behavior in the case of a physically motivated limitation of GND storage is studied. The resulting impact on the mechanical bending response as well as on the predicted size effect is analyzed. Obtained results are discussed and related to experimental findings from the literature. Full article
(This article belongs to the Special Issue Computational Multiscale Modeling and Simulation in Materials Science)
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Open AccessArticle Numerical Investigation of the Fracture Mechanism of Defective Graphene Sheets
Materials 2017, 10(2), 164; doi:10.3390/ma10020164
Received: 23 December 2016 / Revised: 26 January 2017 / Accepted: 8 February 2017 / Published: 11 February 2017
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Abstract
Despite the unique occurrences of structural defects in graphene synthesis, the fracture mechanism of a defective graphene sheet has not been fully understood due to the complexities of the defects. In this study, the fracture mechanism of the monolayer graphene with four common
[...] Read more.
Despite the unique occurrences of structural defects in graphene synthesis, the fracture mechanism of a defective graphene sheet has not been fully understood due to the complexities of the defects. In this study, the fracture mechanism of the monolayer graphene with four common types of defects (single vacancy defect, divacancy defect, Stone–Wales defect and line vacancy defect) were investigated systematically for mechanical loading along armchair and zigzag directions, by using the finite element method. The results demonstrated that all four types of defects could cause significant fracture strength loss in graphene sheet compared with the pristine one. In addition, the results revealed that the stress concentration occurred at the carbon–carbon bonds along the same direction as the displacement loading due to the deficiency or twist of carbon–carbon bonds, resulting in the breaking of the initial crack point in the graphene sheet. The fracture of the graphene sheet was developed following the direction of the breaking of carbon–carbon bonds, which was opposite to that of the displacement loading. Full article
(This article belongs to the Special Issue Computational Multiscale Modeling and Simulation in Materials Science)
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Open AccessArticle Band Gap Tuning in 2D Layered Materials by Angular Rotation
Materials 2017, 10(2), 147; doi:10.3390/ma10020147
Received: 23 October 2016 / Revised: 7 January 2017 / Accepted: 11 January 2017 / Published: 8 February 2017
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Abstract
We present a series of computer-assisted high-resolution transmission electron (HRTEM) simulations to determine Moiré patters by induced twisting effects between slabs at rotational angles of 3°, 5°, 8°, and 16°, for molybdenum disulfide, graphene, tungsten disulfide, and tungsten selenide layered materials. In order
[...] Read more.
We present a series of computer-assisted high-resolution transmission electron (HRTEM) simulations to determine Moiré patters by induced twisting effects between slabs at rotational angles of 3°, 5°, 8°, and 16°, for molybdenum disulfide, graphene, tungsten disulfide, and tungsten selenide layered materials. In order to investigate the electronic structure, a series of numerical simulations using density functional methods (DFT) methods was completed using Cambridge serial total energy package (CASTEP) with a generalized gradient approximation to determine both the band structure and density of states on honeycomb-like new superlattices. Our results indicated metallic transitions when the rotation approached 8° with respect to each other laminates for most of the two-dimensional systems that were analyzed. Full article
(This article belongs to the Special Issue Computational Multiscale Modeling and Simulation in Materials Science)
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Open AccessArticle Mechanical Properties of Auxetic Cellular Material Consisting of Re-Entrant Hexagonal Honeycombs
Materials 2016, 9(11), 900; doi:10.3390/ma9110900
Received: 8 September 2016 / Revised: 17 October 2016 / Accepted: 2 November 2016 / Published: 7 November 2016
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Abstract
A preliminary study of the mechanical properties of auxetic cellular material consisting of re-entrant hexagonal honeycombs is presented. For different scales of the honeycombs, the finite element method (FEM) and experimental models are used to perform a parametric analysis on the effects of
[...] Read more.
A preliminary study of the mechanical properties of auxetic cellular material consisting of re-entrant hexagonal honeycombs is presented. For different scales of the honeycombs, the finite element method (FEM) and experimental models are used to perform a parametric analysis on the effects of the Poisson’s ratio (cell angle) and the relative density (cell thickness) of honeycombs on bearing capacity and dynamic performance of the auxetic material. The analysis demonstrates that the ultimate bearing capacity of the presented auxetic cellular material is scale-independent when the Poisson’s ratio and the relative density are kept constant. The relationship between the geometric parameters and vibration level difference of the honeycombs is also revealed, which can be divided into two converse parts around the Poisson’s ratio v = 1.5 . When v is smaller than −1.5, increasing the cell thickness leads to an increase in the vibration level difference of the honeycombs. Moreover, the dynamic performance of thin-walled honeycombs is greatly influenced by the scale of the honeycombs, especially for the ones with small Poisson’s ratio. These conclusions are verified by a frequency response test and a good agreement between the numerical results and experimental data is achieved. Full article
(This article belongs to the Special Issue Computational Multiscale Modeling and Simulation in Materials Science)
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Open AccessArticle First-Principles Investigation of Phase Stability, Electronic Structure and Optical Properties of MgZnO Monolayer
Materials 2016, 9(11), 877; doi:10.3390/ma9110877
Received: 11 August 2016 / Revised: 20 October 2016 / Accepted: 25 October 2016 / Published: 27 October 2016
Cited by 1 | PDF Full-text (2007 KB) | HTML Full-text | XML Full-text
Abstract
MgZnO bulk has attracted much attention as candidates for application in optoelectronic devices in the blue and ultraviolet region. However, there has been no reported study regarding two-dimensional MgZnO monolayer in spite of its unique properties due to quantum confinement effect. Here, using
[...] Read more.
MgZnO bulk has attracted much attention as candidates for application in optoelectronic devices in the blue and ultraviolet region. However, there has been no reported study regarding two-dimensional MgZnO monolayer in spite of its unique properties due to quantum confinement effect. Here, using density functional theory calculations, we investigated the phase stability, electronic structure and optical properties of MgxZn1−xO monolayer with Mg concentration x range from 0 to 1. Our calculations show that MgZnO monolayer remains the graphene-like structure with various Mg concentrations. The phase segregation occurring in bulk systems has not been observed in the monolayer due to size effect, which is advantageous for application. Moreover, MgZnO monolayer exhibits interesting tuning of electronic structure and optical properties with Mg concentration. The band gap increases with increasing Mg concentration. More interestingly, a direct to indirect band gap transition is observed for MgZnO monolayer when Mg concentration is higher than 75 at %. We also predict that Mg doping leads to a blue shift of the optical absorption peaks. Our results may provide guidance for designing the growth process and potential application of MgZnO monolayer. Full article
(This article belongs to the Special Issue Computational Multiscale Modeling and Simulation in Materials Science)
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Open AccessArticle Cubic C3N: A New Superhard Phase of Carbon-Rich Nitride
Materials 2016, 9(10), 840; doi:10.3390/ma9100840
Received: 5 September 2016 / Revised: 4 October 2016 / Accepted: 12 October 2016 / Published: 17 October 2016
Cited by 7 | PDF Full-text (1752 KB) | HTML Full-text | XML Full-text
Abstract
Using the particle swarm optimization technique, we proposed a cubic superhard phase of C3N (c-C3N) with an estimated Vicker’s hardness of 65 GPa, which is more energetically favorable than the recently proposed o-C3N. The
[...] Read more.
Using the particle swarm optimization technique, we proposed a cubic superhard phase of C3N (c-C3N) with an estimated Vicker’s hardness of 65 GPa, which is more energetically favorable than the recently proposed o-C3N. The c-C3N is the most stable phase in a pressure range of 6.5–15.4 GPa. Above 15.4 GPa, the most energetic favorable high pressure phase R3m-C3N is uncovered. Phonon dispersion and elastic constant calculations confirm the dynamical and mechanical stability of c-C3N and R3m-C3N at ambient pressure. The electronic structure calculations indicate that both c-C3N and R3m-C3N are indirect semiconductor. Full article
(This article belongs to the Special Issue Computational Multiscale Modeling and Simulation in Materials Science)
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Open AccessArticle Physical Properties of PDMS (Polydimethylsiloxane) Microfluidic Devices on Fluid Behaviors: Various Diameters and Shapes of Periodically-Embedded Microstructures
Materials 2016, 9(10), 836; doi:10.3390/ma9100836
Received: 17 August 2016 / Revised: 29 September 2016 / Accepted: 11 October 2016 / Published: 15 October 2016
Cited by 1 | PDF Full-text (4834 KB) | HTML Full-text | XML Full-text
Abstract
Deformable polydimethylsiloxane (PDMS) microfluidic devices embedded with three differently-shaped obstacles (hexagon, square, and triangle) were used to examine the significant challenge to classical fluid dynamics. The significant factors in determining a quasi-steady state value of flow velocity (v)QS and pressure
[...] Read more.
Deformable polydimethylsiloxane (PDMS) microfluidic devices embedded with three differently-shaped obstacles (hexagon, square, and triangle) were used to examine the significant challenge to classical fluid dynamics. The significant factors in determining a quasi-steady state value of flow velocity (v)QS and pressure drop per unit length (∆P/∆x)QS were dependent on the characteristic of embedded microstructures as well as the applied flow rates. The deviation from the theoretical considerations due to PDMS bulging investigated by the friction constant and the normalized friction factor revealed that the largest PDMS bulging observed in hexagonal obstacles had the smallest (∆P/∆x)QS ratios, whereas triangle obstacles exhibited the smallest PDMS bulging, but recorded the largest (∆P/∆x)QS ratios. However, the influence of (v)QS ratio on microstructures was not very significant in this study. The results were close to the predicted values even though some discrepancy may be due to the relatively mean bulging and experimental uncertainty. The influence of deformable PDMS microfluidic channels with various shapes of embedded microstructures was compared with the rigid microchannels. The significant deviation from the classical relation (i.e., f~1/Re) was also observed in hexagonal obstacles and strongly dependent on the channel geometry, the degree of PDMS deformation, and the shapes of the embedded microstructures. Full article
(This article belongs to the Special Issue Computational Multiscale Modeling and Simulation in Materials Science)
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Open AccessArticle Mechanical and Electronic Properties of XC6 and XC12
Materials 2016, 9(9), 726; doi:10.3390/ma9090726
Received: 14 July 2016 / Revised: 14 August 2016 / Accepted: 22 August 2016 / Published: 25 August 2016
Cited by 1 | PDF Full-text (3707 KB) | HTML Full-text | XML Full-text
Abstract
A series of carbon-based superconductors XC6 with high Tc were reported recently. In this paper, based on the first-principles calculations, we studied the mechanical properties of these structures, and further explored the XC12 phases, where the X atoms are from
[...] Read more.
A series of carbon-based superconductors XC6 with high Tc were reported recently. In this paper, based on the first-principles calculations, we studied the mechanical properties of these structures, and further explored the XC12 phases, where the X atoms are from elemental hydrogen to calcium, except noble gas atoms. The mechanically- and dynamically-stable structures include HC6, NC6, and SC6 in XC6 phases, and BC12, CC12, PC12, SC12, ClC12, and KC12 in XC12 phases. The doping leads to a weakening in mechanical properties and an increase in the elastic anisotropy. C6 has the lowest elastic anisotropy, and the anisotropy increases with the atomic number of doping atoms for both XC6 and XC12. Furthermore, the acoustic velocities, Debye temperatures, and the electronic properties are also studied. Full article
(This article belongs to the Special Issue Computational Multiscale Modeling and Simulation in Materials Science)
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Open AccessArticle A New Superhard Phase and Physical Properties of ZrB3 from First-Principles Calculations
Materials 2016, 9(8), 703; doi:10.3390/ma9080703
Received: 25 July 2016 / Revised: 11 August 2016 / Accepted: 15 August 2016 / Published: 22 August 2016
Cited by 3 | PDF Full-text (7787 KB) | HTML Full-text | XML Full-text
Abstract
Using the first-principles particle swarm optimization algorithm for crystal structural prediction, we have predicted a novel monoclinic C2/m structure for ZrB3, which is more energetically favorable than the previously proposed FeB3-, TcP3-, MoB3-,
[...] Read more.
Using the first-principles particle swarm optimization algorithm for crystal structural prediction, we have predicted a novel monoclinic C2/m structure for ZrB3, which is more energetically favorable than the previously proposed FeB3-, TcP3-, MoB3-, WB3-, and OsB3-type structures in the considered pressure range. The new phase is mechanically and dynamically stable, as confirmed by the calculations of its elastic constants and phonon dispersion curve. The calculated large shear modulus (227 GPa) and high hardness (42.2 GPa) show that ZrB3 within the monoclinic phase is a potentially superhard material. The analyses of the electronic density of states and chemical bonding reveal that the strong B–B and B–Zr covalent bonds are attributed to its high hardness. By the quasi-harmonic Debye model, the heat capacity, thermal expansion coefficient and Grüneisen parameter of ZrB3 are also systemically investigated. Full article
(This article belongs to the Special Issue Computational Multiscale Modeling and Simulation in Materials Science)
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Open AccessArticle Crystal Structures and Mechanical Properties of Ca2C at High Pressure
Materials 2016, 9(7), 570; doi:10.3390/ma9070570
Received: 17 May 2016 / Revised: 17 June 2016 / Accepted: 6 July 2016 / Published: 14 July 2016
Cited by 6 | PDF Full-text (2637 KB) | HTML Full-text | XML Full-text
Abstract
Recently, a new high-pressure semiconductor phase of Ca2C (space group Pnma) was successfully synthesized, it has a low-pressure metallic phase (space group C2/m). In this paper, a systematic investigation of the pressure-induced phase transition of Ca2
[...] Read more.
Recently, a new high-pressure semiconductor phase of Ca2C (space group Pnma) was successfully synthesized, it has a low-pressure metallic phase (space group C2/m). In this paper, a systematic investigation of the pressure-induced phase transition of Ca2C is studied on the basis of first-principles calculations. The calculated enthalpy reveals that the phase transition which transforms from C2/m-Ca2C to Pnma-Ca2C occurs at 7.8 GPa, and it is a first-order phase transition with a volume drop of 26.7%. The calculated elastic constants show that C2/m-Ca2C is mechanically unstable above 6.4 GPa, indicating that the structural phase transition is due to mechanical instability. Both of the two phases exhibit the elastic anisotropy. The semiconductivity of Pnma-Ca2C and the metallicity of C2/m-Ca2C have been demonstrated by the electronic band structure calculations. The quasi-direct band gap of Pnma-Ca2C at 0 GPa is 0.86 eV. Furthermore, the detailed analysis of the total and partial density of states is performed to show the specific contribution to the Fermi level. Full article
(This article belongs to the Special Issue Computational Multiscale Modeling and Simulation in Materials Science)
Open AccessArticle Structural Transitions in Nanosized Zn0.97Al0.03O Powders under High Pressure Analyzed by in Situ Angle-Dispersive X-ray Diffraction
Materials 2016, 9(7), 561; doi:10.3390/ma9070561
Received: 25 May 2016 / Revised: 28 June 2016 / Accepted: 7 July 2016 / Published: 12 July 2016
Cited by 1 | PDF Full-text (2048 KB) | HTML Full-text | XML Full-text
Abstract
Nanosized aluminum-doped zinc oxide Zn1−xAlxO (AZO) powders (AZO-NPs) with x = 0.01, 0.03, 0.06, 0.09 and 0.11 were synthesized by chemical precipitation method. The thermogravimetric analysis (TGA) indicated that the precursors were converted to oxides from hydroxides near
[...] Read more.
Nanosized aluminum-doped zinc oxide Zn1−xAlxO (AZO) powders (AZO-NPs) with x = 0.01, 0.03, 0.06, 0.09 and 0.11 were synthesized by chemical precipitation method. The thermogravimetric analysis (TGA) indicated that the precursors were converted to oxides from hydroxides near 250 °C, which were then heated to 500 °C for subsequent thermal processes to obtain preliminary powders. The obtained preliminary powders were then calcined at 500 °C for three hours. The structure and morphology of the products were measured and characterized by angle-dispersive X-ray diffraction (ADXRD) and scanning electron microscopy (SEM). ADXRD results showed that AZO-NPs with Al content less than 11% exhibited würtzite zinc oxide structure and there was no other impurity phase in the AZO-NPs, suggesting substitutional doping of Al on Zn sites. The Zn0.97Al0.03O powders (A3ZO-NPs) with grain size of about 21.4 nm were used for high-pressure measurements. The in situ ADXRD measurements revealed that, for loading run, the pressure-induced würtzite (B4)-to-rocksalt (B1) structural phase transition began at 9.0(1) GPa. Compared to the predicted phase-transition pressure of ~12.7 GPa for pristine ZnO nanocrystals of similar grain size (~21.4 nm), the transition pressure for the present A3ZO-NPs exhibited a reduction of ~3.7 GPa. The significant reduction in phase-transition pressure is attributed to the effects of highly selective site occupation, namely Zn2+ and Al3+, were mainly found in tetrahedral and octahedral sites, respectively. Full article
(This article belongs to the Special Issue Computational Multiscale Modeling and Simulation in Materials Science)
Open AccessArticle Mechanical Properties and Atomic Explanation of Plastic Deformation for Diamond-Like BC2
Materials 2016, 9(7), 514; doi:10.3390/ma9070514
Received: 28 April 2016 / Revised: 14 June 2016 / Accepted: 22 June 2016 / Published: 24 June 2016
Cited by 1 | PDF Full-text (2038 KB) | HTML Full-text | XML Full-text
Abstract
Motivated by a recently predicted structure of diamond-like BC2 with a high claimed hardness of 56 GPa (J. Phys. Chem. C 2010, 114, 22688–22690), we focus on whether this tetragonal BC2 (t-BC2) is superhard
[...] Read more.
Motivated by a recently predicted structure of diamond-like BC2 with a high claimed hardness of 56 GPa (J. Phys. Chem. C 2010, 114, 22688–22690), we focus on whether this tetragonal BC2 (t-BC2) is superhard or not in spite of such an ultrahigh theoretical hardness. The mechanical properties of t-BC2 were thus further extended by using the first principles in the framework of density functional theory. Our results suggest that the Young’s and shear moduli of t-BC2 exhibit a high degree of anisotropy. For the weakest shear direction, t-BC2 undergoes an electronic instability and structural collapse upon a shear strain of about 0.11, with its theoretically ideal strength of only 36.2 GPa. Specifically, the plastic deformation under shear strain along the (110)[001] direction can be attributed to the breaking of d1 B–C bonds. Full article
(This article belongs to the Special Issue Computational Multiscale Modeling and Simulation in Materials Science)
Open AccessArticle A Stress-Induced Martensitic Transformation in Aged Ti49Ni51 Alloy after High-Velocity Impact
Materials 2016, 9(7), 500; doi:10.3390/ma9070500
Received: 4 May 2016 / Revised: 3 June 2016 / Accepted: 16 June 2016 / Published: 23 June 2016
PDF Full-text (4905 KB) | HTML Full-text | XML Full-text
Abstract
The effects of a high-velocity impact on the microstructure, phase transformation and mechanical property of aged Ti49Ni51 alloy are investigated. The transformation behavior and microstructure along the impact direction after impact emerge with regionalization characteristics, including a deformed region near
[...] Read more.
The effects of a high-velocity impact on the microstructure, phase transformation and mechanical property of aged Ti49Ni51 alloy are investigated. The transformation behavior and microstructure along the impact direction after impact emerge with regionalization characteristics, including a deformed region near the crater (0–4 mm) and an un-deformed region of the distal crater (5–6 mm). Stress-induced martensite is the main deformation mechanism in the deforming region of aged Ti49Ni51 alloy under high-velocity impact. Full article
(This article belongs to the Special Issue Computational Multiscale Modeling and Simulation in Materials Science)
Open AccessArticle A Reinvestigation of a Superhard Tetragonal sp3 Carbon Allotrope
Materials 2016, 9(6), 484; doi:10.3390/ma9060484
Received: 5 May 2016 / Revised: 8 June 2016 / Accepted: 13 June 2016 / Published: 17 June 2016
Cited by 3 | PDF Full-text (2488 KB) | HTML Full-text | XML Full-text
Abstract
I4¯–carbon was first proposed by Zhang et al., this paper will report regarding this phase of carbon. The present paper reports the structural and elastic properties of the three-dimensional carbon allotrope I4¯–carbon using first-principles density functional
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I 4 ¯ –carbon was first proposed by Zhang et al., this paper will report regarding this phase of carbon. The present paper reports the structural and elastic properties of the three-dimensional carbon allotrope I 4 ¯ –carbon using first-principles density functional theory. The related enthalpy, elastic constants, and phonon spectra confirm that the newly-predicted I 4 ¯ –carbon is thermodynamically, mechanically, and dynamically stable. The calculated mechanical properties indicate that I 4 ¯ –carbon has a larger bulk modulus (393 GPa), shear modulus (421 GPa), Young’s modulus (931 GPa), and hardness (55.5 GPa), all of which are all slightly larger than those of c-BN. The present results indicate that I 4 ¯ –carbon is a superhard material and an indirect-band-gap semiconductor. Moreover, I 4 ¯ –carbon shows a smaller elastic anisotropy in its linear bulk modulus, shear anisotropic factors, universal anisotropic index, and Young’s modulus. Full article
(This article belongs to the Special Issue Computational Multiscale Modeling and Simulation in Materials Science)
Open AccessArticle The Lateral Compressive Buckling Performance of Aluminum Honeycomb Panels for Long-Span Hollow Core Roofs
Materials 2016, 9(6), 444; doi:10.3390/ma9060444
Received: 9 May 2016 / Revised: 9 May 2016 / Accepted: 27 May 2016 / Published: 3 June 2016
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Abstract
To solve the problem of critical buckling in the structural analysis and design of the new long-span hollow core roof architecture proposed in this paper (referred to as a “honeycomb panel structural system” (HSSS)), lateral compression tests and finite element analyses were employed
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To solve the problem of critical buckling in the structural analysis and design of the new long-span hollow core roof architecture proposed in this paper (referred to as a “honeycomb panel structural system” (HSSS)), lateral compression tests and finite element analyses were employed in this study to examine the lateral compressive buckling performance of this new type of honeycomb panel with different length-to-thickness ratios. The results led to two main conclusions: (1) Under the experimental conditions that were used, honeycomb panels with the same planar dimensions but different thicknesses had the same compressive stiffness immediately before buckling, while the lateral compressive buckling load-bearing capacity initially increased rapidly with an increasing honeycomb core thickness and then approached the same limiting value; (2) The compressive stiffnesses of test pieces with the same thickness but different lengths were different, while the maximum lateral compressive buckling loads were very similar. Overall instability failure is prone to occur in long and flexible honeycomb panels. In addition, the errors between the lateral compressive buckling loads from the experiment and the finite element simulations are within 6%, which demonstrates the effectiveness of the nonlinear finite element analysis and provides a theoretical basis for future analysis and design for this new type of spatial structure. Full article
(This article belongs to the Special Issue Computational Multiscale Modeling and Simulation in Materials Science)
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Open AccessArticle Two Novel C3N4 Phases: Structural, Mechanical and Electronic Properties
Materials 2016, 9(6), 427; doi:10.3390/ma9060427
Received: 26 April 2016 / Revised: 20 May 2016 / Accepted: 24 May 2016 / Published: 30 May 2016
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Abstract
We systematically studied the physical properties of a novel superhard (t-C3N4) and a novel hard (m-C3N4) C3N4 allotrope. Detailed theoretical studies of the structural properties, elastic properties, density
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We systematically studied the physical properties of a novel superhard (t-C3N4) and a novel hard (m-C3N4) C3N4 allotrope. Detailed theoretical studies of the structural properties, elastic properties, density of states, and mechanical properties of these two C3N4 phases were carried out using first-principles calculations. The calculated elastic constants and the hardness revealed that t-C3N4 is ultra-incompressible and superhard, with a high bulk modulus of 375 GPa and a high hardness of 80 GPa. m-C3N4 and t-C3N4 both exhibit large anisotropy with respect to Poisson’s ratio, shear modulus, and Young’s modulus. Moreover, m-C3N4 is a quasi-direct-bandgap semiconductor, with a band gap of 4.522 eV, and t-C3N4 is also a quasi-direct-band-gap semiconductor, with a band gap of 4.210 eV, with the HSE06 functional. Full article
(This article belongs to the Special Issue Computational Multiscale Modeling and Simulation in Materials Science)
Open AccessArticle Discrete Element Method Modeling of the Rheological Properties of Coke/Pitch Mixtures
Materials 2016, 9(5), 334; doi:10.3390/ma9050334
Received: 2 February 2016 / Revised: 22 April 2016 / Accepted: 28 April 2016 / Published: 4 May 2016
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Abstract
Rheological properties of pitch and pitch/coke mixtures at temperatures around 150 °C are of great interest for the carbon anode manufacturing process in the aluminum industry. In the present work, a cohesive viscoelastic contact model based on Burger’s model is developed using the
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Rheological properties of pitch and pitch/coke mixtures at temperatures around 150 °C are of great interest for the carbon anode manufacturing process in the aluminum industry. In the present work, a cohesive viscoelastic contact model based on Burger’s model is developed using the discrete element method (DEM) on the YADE, the open-source DEM software. A dynamic shear rheometer (DSR) is used to measure the viscoelastic properties of pitch at 150 °C. The experimental data obtained is then used to estimate the Burger’s model parameters and calibrate the DEM model. The DSR tests were then simulated by a three-dimensional model. Very good agreement was observed between the experimental data and simulation results. Coke aggregates were modeled by overlapping spheres in the DEM model. Coke/pitch mixtures were numerically created by adding 5, 10, 20, and 30 percent of coke aggregates of the size range of 0.297–0.595 mm (−30 + 50 mesh) to pitch. Adding up to 30% of coke aggregates to pitch can increase its complex shear modulus at 60 Hz from 273 Pa to 1557 Pa. Results also showed that adding coke particles increases both storage and loss moduli, while it does not have a meaningful effect on the phase angle of pitch. Full article
(This article belongs to the Special Issue Computational Multiscale Modeling and Simulation in Materials Science)
Open AccessArticle The Mechanical and Electronic Properties of Carbon-Rich Silicon Carbide
Materials 2016, 9(5), 333; doi:10.3390/ma9050333
Received: 29 March 2016 / Revised: 25 April 2016 / Accepted: 27 April 2016 / Published: 30 April 2016
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Abstract
A systematic investigation of structural, mechanical, anisotropic, and electronic properties of SiC2 and SiC4 at ambient pressure using the density functional theory with generalized gradient approximation is reported in this work. Mechanical properties, i.e., the elastic constants and elastic modulus,
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A systematic investigation of structural, mechanical, anisotropic, and electronic properties of SiC2 and SiC4 at ambient pressure using the density functional theory with generalized gradient approximation is reported in this work. Mechanical properties, i.e., the elastic constants and elastic modulus, have been successfully obtained. The anisotropy calculations show that SiC2 and SiC4 are both anisotropic materials. The features in the electronic band structures of SiC2 and SiC4 are analyzed in detail. The biggest difference between SiC2 and SiC4 lies in the universal elastic anisotropy index and band gap. SiC2 has a small universal elastic anisotropy index value of 0.07, while SiC2 has a much larger universal elastic anisotropy index value of 0.21, indicating its considerable anisotropy compared with SiC2. Electronic structures of SiC2 and SiC4 are calculated by using hybrid functional HSE06. The calculated results show that SiC2 is an indirect band gap semiconductor, while SiC4 is a quasi-direct band gap semiconductor. Full article
(This article belongs to the Special Issue Computational Multiscale Modeling and Simulation in Materials Science)
Open AccessArticle Si96: A New Silicon Allotrope with Interesting Physical Properties
Materials 2016, 9(4), 284; doi:10.3390/ma9040284
Received: 22 January 2016 / Revised: 2 April 2016 / Accepted: 7 April 2016 / Published: 13 April 2016
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Abstract
The structural mechanical properties and electronic properties of a new silicon allotrope Si96 are investigated at ambient pressure by using a first-principles calculation method with the ultrasoft pseudopotential scheme in the framework of generalized gradient approximation. The elastic constants and phonon calculations
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The structural mechanical properties and electronic properties of a new silicon allotrope Si96 are investigated at ambient pressure by using a first-principles calculation method with the ultrasoft pseudopotential scheme in the framework of generalized gradient approximation. The elastic constants and phonon calculations reveal that Si96 is mechanically and dynamically stable at ambient pressure. The conduction band minimum and valence band maximum of Si96 are at the R and G point, which indicates that Si96 is an indirect band gap semiconductor. The anisotropic calculations show that Si96 exhibits a smaller anisotropy than diamond Si in terms of Young’s modulus, the percentage of elastic anisotropy for bulk modulus and shear modulus, and the universal anisotropic index AU. Interestingly, most silicon allotropes exhibit brittle behavior, in contrast to the previously proposed ductile behavior. The void framework, low density, and nanotube structure make Si96 quite attractive for applications such as hydrogen storage and electronic devices that work at extreme conditions, and there are potential applications in Li-battery anode materials. Full article
(This article belongs to the Special Issue Computational Multiscale Modeling and Simulation in Materials Science)

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Open AccessCorrection Correction: A Novel Silicon Allotrope in the Monoclinic Phase. Materials 2017, 10, 441
Materials 2017, 10(5), 561; doi:10.3390/ma10050561
Received: 18 May 2017 / Revised: 18 May 2017 / Accepted: 19 May 2017 / Published: 22 May 2017
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Abstract
The authors would like to make the following correction to their paper[1]. In this paper,we wrongly listed the coordinates of the new silicon allotrope [...]
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(This article belongs to the Special Issue Computational Multiscale Modeling and Simulation in Materials Science)
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