A comparative ab initio study of the ‘ideal’ strength of single crystal α- and β-Si3N4

2004 ◽  
Vol 52 (1) ◽  
pp. 233-238 ◽  
Author(s):  
Shigenobu Ogata ◽  
Naoto Hirosaki ◽  
Cenk Kocer ◽  
Yoji Shibutani
Keyword(s):  
Single Crystal ◽  
Ab Initio ◽  
Ideal Strength ◽  
Ab Initio Study ◽  
The Ideal

An ab initio study of the ideal tensile and shear strength of single-crystal β–Si3N4

2003 ◽  
Vol 18 (5) ◽  
pp. 1168-1172 ◽  
Author(s):  
Shigenobu Ogata ◽  
Naoto Hirosaki ◽  
Cenk Kocer ◽  
Yoji Shibutani
Keyword(s):  
Shear Strength ◽  
Single Crystal ◽  
Ab Initio ◽  
Density Functional ◽  
Strain Curve ◽  
High Strength ◽  
Indentation Hardness ◽  
Ideal Strength ◽  
Vickers Indentation ◽  
The Ideal

In this study, the ideal tensile and shear strength of single-crystal β–Si3N4 was calculated using an ab initio density functional technique. The stress-strain curve of the silicon nitride polymorph was calculated from simulations of uniaxial strain deformation. In particular, the ideal strength calculated for an applied ∈11 tensile strain was estimated to be approximately 57 GPa. Recently, a good correlation was reported between the shear modulus of high-strength materials and the experimentally determined Vickers indentation hardness value. Using the reported correlation an estimate was made of the Vickers indentation hardness of single-crystal β–Si3N4: approximately 20.4 GPa.

271 Ab initio study of ideal strength of Cu nano-film

2006 ◽  
Vol 2006.19 (0) ◽  
pp. 627-628
Author(s):  
Akihiro KUSHIMA ◽  
Yoshitaka UMENO ◽  
Takayuki KITAMURA
Keyword(s):  
Ab Initio ◽  
Ideal Strength ◽  
Ab Initio Study

Magnetic anisotropy of CoII–WVferromagnet: single crystal and ab initio study

CrystEngComm ◽  
2013 ◽  
Vol 15 (13) ◽  
pp. 2378-2385 ◽  
Author(s):  
Szymon Chorazy ◽  
Robert Podgajny ◽  
Anna M. Majcher ◽  
Wojciech Nitek ◽  
Michał Rams ◽  
...  
Keyword(s):  
Magnetic Anisotropy ◽  
Single Crystal ◽  
Ab Initio ◽  
Ab Initio Study

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.

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