Influence of lattice vacancies on the structural, electronic, and cohesive properties of niobium and molybdenum borides from first-principles calculations

2006 ◽  
Vol 73 (14) ◽  
Author(s):  
I. R. Shein ◽  
A. L. Ivanovskii
Keyword(s):  
First Principles ◽  
First Principles Calculations ◽  
Cohesive Properties ◽  
Lattice Vacancies

Effect of Alloying Elements and Impurity (N) on Bulk and Grain Boundary Cohesion in Cr-Base Alloys

2015 ◽  
Vol 1119 ◽  
pp. 569-574 ◽  
Author(s):  
Victor Nikolaevich Butrim ◽  
Igor M. Razumovskii ◽  
A.G. Beresnev ◽  
A. Kartsev ◽  
Vsevolod I. Razumovskiy ◽  
...  
Keyword(s):  
Grain Boundary ◽  
First Principles ◽  
Base Alloy ◽  
Interatomic Bond ◽  
Strength Properties ◽  
First Principles Calculations ◽  
Alloying System ◽  
Segregation Behavior ◽  
Cohesive Properties ◽  
Theoretical Results

Effect of comprehensive alloying system (W, Ta, Nb, Mo, V, Hf, Ti, Zr, Ni) and impurity N on cohesive properties of the bulk and the special high-angle grain boundary (GB) Σ5 (210)[100] in Cr-base alloys, as well as segregation behavior of impurities at the GB and the (210) free surface are studied by first principles calculations. The analysis of the data obtained allows us to single out W, Ta as the best and nitrogen as the worst interatomic bond strengthening elements for both the bulk and GB in Cr-base alloys. To verify these theoretical results by means of experiment, we investigated an influence of W (up to 10 wt. %), and (Ta, Nb, Hf and Zr) on mechanical properties of Cr-base alloy. We observed an increasing of the strength properties due to W addition and increasing of the plasticity as a result of (Ta, Nb, Hf, Zr) adding.

Cohesive properties of the crystalline phases of twenty proteinogenic α-aminoacids from first-principles calculations

2019 ◽  
Vol 21 (34) ◽  
pp. 18501-18515 ◽  
Author(s):  
Ctirad Červinka ◽  
Michal Fulem
Keyword(s):  
Amino Acid ◽  
Proton Transfer ◽  
First Principles ◽  
First Principles Calculations ◽  
Crystalline Phases ◽  
Proteinogenic Amino Acid ◽  
Cohesive Properties

Sublimation enthalpies and proton transfer energies are calculated with a fair accuracy from the first principles for the complete 20 proteinogenic amino acid set.

scholarly journals New Cr-Ni-Base Alloy for High-Temperature Applications Designed on the Basis of First Principles Calculations

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
V. I. Razumovskiy ◽  
D. Scheiber ◽  
I. M. Razumovskii ◽  
V. N. Butrim ◽  
A. S. Trushnikova ◽  
...  
Keyword(s):  
High Temperature ◽  
First Principles ◽  
Base Alloy ◽  
Dual Phase ◽  
First Principles Calculations ◽  
Alloying Additions ◽  
Alloying System ◽  
Cohesive Properties ◽  
High Temperature Alloys ◽  
Ni Alloy

We use ab initio calculations to analyze the influence of 4d and 5d transition metal alloying elements on cohesive properties of the bulk and a representative grain boundary in Cr within the framework of the Rice–Thomson–Wang approach. The results obtained for Cr are combined with the analogous results for Ni to select Ta and Nb as promising alloying additions to dual-phase (α/γ) Cr-Ni-base high-temperature alloys. Ta and Nb are added to the alloying system of an existing alloy I (Cr-Ni-W-V-Ti) in an attempt to design a chemical composition of a new alloy II (Cr-Ni-W-V-Ti) + (Ta-Nb). Investigation of the microstructure of the Ta-bearing Cr-Ni-alloy reveals a Ta enrichment of large γ-areas near GBs in α-matrix that we consider as potency to increase the cohesive strength of GBs and the cohesive energy of the bulk in γ-phase. Mechanical testing of alloys I and II demonstrates that the alloy II has improved tensile strength and creep resistance at high temperatures.

Electronic Structure and X-ray Absorption Spectra of Rutile TiO2 Using First-Principles Calculations

2014 ◽  
Vol 52 (12) ◽  
pp. 1025-1029
Author(s):  
Min-Wook Oh ◽  
Tae-Gu Kang ◽  
Byungki Ryu ◽  
Ji Eun Lee ◽  
Sung-Jae Joo ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Absorption Spectra ◽  
First Principles ◽  
First Principles Calculations ◽  
Rutile Tio2 ◽  
X Ray ◽  
X Ray Absorption

To Bend or Not to Bend, the Dilemma of Multiple Bonds

2019 ◽  
Author(s):  
Michele Pizzocchero ◽  
Matteo Bonfanti ◽  
Rocco Martinazzo
Keyword(s):  
First Principles ◽  
2D Materials ◽  
Main Group ◽  
First Principles Calculations ◽  
Group 14 ◽  
Multiple Bonds ◽  
Main Group Elements ◽  
Structural Distortions

The manuscript addresses the issue of the structural distortions occurring at multiple bonds between high main group elements, focusing on group 14. These distortions are known as trans-bending in silenes, disilenes and higher group analogues, and buckling in 2D materials likes silicene and germanene. A simple but correlated \sigma + \pi model is developed and validated with first-principles calculations, and used to explain the different behaviour of second- and higher- row elements.

Thermodynamic Stability of Hexagonal and Rhombohedral Bn at Cvd Conditions from Van der Waals Corrected First Principles Calculations

2019 ◽  
Author(s):  
Henrik Pedersen ◽  
Björn Alling ◽  
Hans Högberg ◽  
Annop Ektarawong
Keyword(s):  
Thin Films ◽  
Thermodynamic Stability ◽  
First Principles ◽  
Thermal Equilibrium ◽  
Density Functional ◽  
Van Der Waals ◽  
Chemical Vapor ◽  
First Principles Calculations ◽  
Functional Theory ◽  
The Stability

Thin films of boron nitride (BN), particularly the sp<sup>2</sup>-hybridized polytypes hexagonal BN (h-BN) and rhombohedral BN (r-BN) are interesting for several electronic applications given band gaps in the UV. They are typically deposited close to thermal equilibrium by chemical vapor deposition (CVD) at temperatures and pressures in the regions 1400-1800 K and 1000-10000 Pa, respectively. In this letter, we use van der Waals corrected density functional theory and thermodynamic stability calculations to determine the stability of r-BN and compare it to that of h-BN as well as to cubic BN and wurtzitic BN. We find that r-BN is the stable sp<sup>2</sup>-hybridized phase at CVD conditions, while h-BN is metastable. Thus, our calculations suggest that thin films of h-BN must be deposited far from thermal equilibrium.

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