The Effect of Impurities on the Ideal Tensile Strength of Covalent Crystals - Ab-Initio Quantum Molecular Dynamics Calculations

1993 ◽  
Vol 327 ◽  
Author(s):  
Y.M. Huang ◽  
J.C.H. Spence ◽  
Otto F. Sankey
Keyword(s):  
Tensile Strength ◽  
Local Density ◽  
Impurity Effect ◽  
Quantum Molecular Dynamics ◽  
Crystalline Solids ◽  
Ideal Strength ◽  
Molecular Dynamics Calculations ◽  
Effect Of Impurities ◽  
Structure Calculations ◽  
The Ideal

AbstractUsing first-principles electronic structure calculations in the local density approximation combined with lattice dynamics, we investigate the effect of III/V impurities on the ideal strength of covalent solids (C, Si, and Ge). Our results show that undoped crystalline solids are stronger in tension along [111] than n-type crystalline solids. P doping has a negligible effect on ideal tensile strength, while n-type doping causes a small reduction in strength of about 6%. The n-type impurity effect is due to the negative (repulsive) contribution from the bottom state of the distorted conduction band to the ideal strength of the solid.

The mechanical properties of perfect crystals I. The ideal strength

1972 ◽  
Vol 330 (1582) ◽  
pp. 291-308 ◽  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Shear Strength ◽  
Sodium Chloride ◽  
Room Temperature ◽  
Cleavage Plane ◽  
Ideal Strength ◽  
Lennard Jones ◽  
Computer Calculations ◽  
The Ideal

In this paper we present computer calculations of the ideal strength of crystals of sodium chloride and argon, for a variety of modes of homogeneous deformation. As models of the interatomic binding we employ the simple, two-body, central-force Born-Mayer and Lennard-Jones potentials respectively. The calculations for argon are appropriate to absolute zero, those for sodium chloride to room temperature. The results indicate a very marked anisotropy of the ideal tensile strength for sodium chloride, with a pronounced minimum at <100>, which is consistent with the observed cleavage on this plane. The ideal tensile strength of argon is shown to be much less dependent on orientation, which accords with the lack of any obvious cleavage plane in this material. We also make some estimates of the ideal shear strength, and find this to be a minimum for {111} <112> shear for both argon and sodium chloride.

Ab Initio DFT Study of Ideal Strength of Crystal and Surfaces in Covalent Systems

2008 ◽  
Vol 1086 ◽  
Author(s):  
Yoshitaka Umeno
Keyword(s):  
Tensile Strength ◽  
Ab Initio ◽  
Normal Stress ◽  
Density Functional ◽  
Level Structure ◽  
High Strength ◽  
Nucleation Site ◽  
Dislocation Nucleation ◽  
Ideal Strength ◽  
The Ideal

AbstractAb initio density functional theory (DFT) calculations were performed to examine various factors which may influence the ideal strength, namely multiaxial loading condition and structure with low symmetry. First, the effect of normal stress on the ideal shear strength (ISS) in covalent crystals, Si, C, Ge and SiC, was evaluated. It was found that the response of ISS to normal stress differs depending on the material, while in metals the trend is unchanged. Obtained ISS as a function of normal stress is useful to understand criteria of dislocation nucleation in a pristine crystal because local lattices at the nucleation site undergo superimposed stress components in experiment. Secondly the ideal tensile strength of silicon surface was evaluated to examine how atomistic-level structure affects the mechanical property. The theoretical tensile strength of Si nanofilms with (100) surface, which is flat with dimer-row structures, shows only 20-30% reduction even though the thickness is down to 1 nm, meaning that the flat surface possesses high strength.

scholarly journals Toward a better understanding of the enhancing/embrittling effects of impurities in Nickel grain boundaries

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
El Tayeb Bentria ◽  
Ibn Khaldoun Lefkaier ◽  
Ali Benghia ◽  
Bachir Bentria ◽  
Mohammed Benali Kanoun ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Grain Boundaries ◽  
Magnetic Moment ◽  
Density Functional ◽  
Density Functional Theory Calculation ◽  
Impurity Effect ◽  
Fundamental Understanding ◽  
Effect Of Impurities ◽  
Cohesive Energies ◽  
Theory Calculation

Abstract The fracture path follows grain boundaries (GB) in most metallic system under tensile test. In general, impurities, even in ppm concentration, that segregate to these boundaries can remarkably change materials mechanical properties. Predicting impurities segregation effects in Nickel super-alloys might not be seen as intuitive and perhaps more fundamental understanding is needed. We performed a density functional theory calculation to elucidate the effect of eight light elements (B, C, N, O, Al, Si, P and S) and twelve transition metal elements (Tc, Ti, V, Cr, Mn, Zr, Nb, Mo, Hf, Ta, W, Re) on Nickel ∑5(210) grain boundary formation and its Ni free surface. The effect of impurities was carefully examined by calculating different properties such as segregation, binding and cohesive energies, strengthening/embrittling potency and the theoretical tensile strength. Additionally, we employed the electron density differences and magnetic effects to explain why and how impurities such as B, S, V, Nb, Mn and W affect Nickel ∑5 GB. We used the generated data calculated on equal footing, to develop a fundamental understanding on impurity effect. A clear and strong correlation is found between difference in magnetic moment change between isolated and imbedded impurity atom on one hand and the tensile strength on the other hand. The higher the loss of the magnetic moment, the more the impurity consolidates the GB.

The effect of impurities on the ideal tensile strength of silicon

1994 ◽  
Vol 70 (1) ◽  
pp. 53-62 ◽  
Author(s):  
Y. M. Huang ◽  
J. C. H. Spence ◽  
Otto F. Sankey
Keyword(s):  
Tensile Strength ◽  
Effect Of Impurities ◽  
The Ideal

Processing of Nanoporous Gold by Dealloying and its Morphological Control

2007 ◽  
Vol 561-565 ◽  
pp. 1657-1660 ◽  
Author(s):  
Masataka Hakamada ◽  
Mamoru Mabuchi
Keyword(s):  
Mechanical Properties ◽  
Thermal Treatment ◽  
Acid Treatment ◽  
Nanoporous Gold ◽  
Anisotropic Structure ◽  
Ideal Strength ◽  
Pore Characteristics ◽  
Very High ◽  
Ligament Size ◽  
The Ideal

Nanoporous gold was fabricated by dealloying and their pore characteristics were further modified by thermal or acid treatment. The fabricated nanoporous gold had a ligament size of approximately 5 nm. Thermal treatment on the nanoporous gold increased the ligament size to approximately 500 nm. During the thermal treatment, ligaments are bonded across the cracks which had been generated during the dealloying. Acid treatment also increased the ligament size to approximately 500 nm; however, the acid treatment had a different effect on the pore characteristics from the thermal treatment. As a result, nanoporous gold prism microassembly with anisotropic structure was spontaneously fabricated by the acid treatment. The mechanical properties of nanoporous gold were also examined. It is estimated that the yield strength of nanosized ligaments in nanoporous gold is very high and close to the ideal strength of gold.

Anab initiocalculation of the ideal tensile strength of β-silicon nitride

2001 ◽  
Vol 64 (17) ◽  
Author(s):  
Shigenobu Ogata ◽  
Naoto Hirosaki ◽  
Cenk Kocer ◽  
Hiroshi Kitagawa
Keyword(s):  
Tensile Strength ◽  
Silicon Nitride ◽  
The Ideal

Electronic bonding characteristics of hydrogen in bcc iron: Part I. Interstitials

1996 ◽  
Vol 11 (9) ◽  
pp. 2206-2213 ◽  
Author(s):  
Yoshio Itsumi ◽  
D. E. Ellis
Keyword(s):  
Density Functional ◽  
Local Density ◽  
Lattice Relaxation ◽  
Experimental Result ◽  
Functional Formalism ◽  
Discrete Variational Method ◽  
Bcc Iron ◽  
Bond Strengths ◽  
Bonding Characteristics ◽  
Structure Calculations

Electronic structure calculations were carried out for bcc iron (Fe) clusters with or without hydrogen (H), and also involving a vacancy, using the self-consistent Discrete Variational method (DV-Xα) within the local density functional formalism. Bonding characteristics investigated show the following: (i) Interstitial H notably decreases interatomic Fe–Fe bond strengths, but acts over a small distance (within 0.3 nm). (ii) In the perfect Fe lattice field, interstitial H feels a repulsive force at any site. As a result of lattice relaxation, volume expansion may be expected. (iii) H in combination with a vacancy prefers a position shifted from the octahedral site toward the vacancy. This is fairly consistent with an experimental result.

On the Ideal Strength of Crystals

1989 ◽  
Vol 151 (1) ◽  
pp. 85-93 ◽  
Author(s):  
J. Pokluda ◽  
P. Šandera
Keyword(s):  
Ideal Strength ◽  
The Ideal

O 1s Core-Level Positions of Bi2Sr2CaCu2O8-x by OKα-Ray Emission

1989 ◽  
Vol 44 (9) ◽  
pp. 780-784
Author(s):  
F. Burgäzy ◽  
C. Politis ◽  
P. Lamparter ◽  
S. Steeb
Keyword(s):  
Binding Energy ◽  
Energy Level ◽  
Photoelectron Spectrum ◽  
Local Density ◽  
Binding Energies ◽  
Core Level ◽  
X Ray ◽  
Band Structure Calculations ◽  
Density Band ◽  
Structure Calculations

Abstract The measured O Kα X-ray emission spectrum of the high-Tc superconductor Bi2Sr2CaCu2O8-x is compared with a spectrum based on local density band structure calculations. By taking also into account the shape of the measured O 1s X-ray photoelectron spectrum an energy level diagram for the O 1s core-level binding energies of the three different oxygen sites is constructed. The O 1s binding energy in the Bi2O2-layers is found to be about the same as that one in the SrO-layers, whereas the binding energy in the CuO2-layers is lower by about 0.5 eV.

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