A comparable study of Fe//MCs (M = Ti, V) interfaces by first-principles method: The chemical bonding, work of adhesion and electronic structures

The geometries, energetics and electronic structures of Co13, Mo13, Co12Mo and Mo12Co clusters are systematically investigated by using the first principles method combined with a genetic algorithm.

Download Full-text

Effects of Doped Elements (Si, Cr, W and Nb) on the Stability, Mechanical Properties and Electronic Structures of MoAlB Phase by the First-Principles Calculation

Materials ◽

10.3390/ma13194221 ◽

2020 ◽

Vol 13 (19) ◽

pp. 4221

Author(s):

Yongxin Jian ◽

Zhifu Huang ◽

Yu Wang ◽

Jiandong Xing

Keyword(s):

Mechanical Properties ◽

Chemical Bonding ◽

First Principles ◽

Electronic Structures ◽

Density Functional ◽

Formation Enthalpy ◽

First Principles Calculation ◽

Elemental Doping ◽

The Stability ◽

W Doping

First-principles calculations based on density functional theory (DFT) have been performed to explore the effects of Si, Cr, W, and Nb elements on the stability, mechanical properties, and electronic structures of MoAlB ternary boride. The five crystals, with the formulas of Mo4Al4B4, Mo4Al3SiB4, Mo3CrAl4B4, Mo3WAl4B4, and Mo3NbAl4B4, have been respectively established. All the calculated crystals are thermodynamically stable, according to the negative cohesive energy and formation enthalpy. By the calculation of elastic constants, the mechanical moduli and ductility evolutions of MoAlB with elemental doping can be further estimated, with the aid of B/G and Poisson’s ratios. Si and W doping cannot only enhance the Young’s modulus of MoAlB, but also improve the ductility to some degree. Simultaneously, the elastic moduli of MoAlB are supposed to become more isotropic after Si and W addition. However, Cr and Nb doping plays a negative role in ameliorating the mechanical properties. Through the analysis of electronic structures and chemical bonding, the evolutions of chemical bondings can be disclosed with the addition of dopant. The enhancement of B-B, Al/Si-B, and Al/Si-Mo bondings takes place after Si substitution, and W addition apparently intensifies the bonding with B and Al. In this case, the strengthening of chemical bonding after Si and W doping exactly accounts for the improvement of mechanical properties of MoAlB. Additionally, Si doping can also improve the Debye temperature and melting point of the MoAlB crystal. Overall, Si element is predicted to be the optimized dopant to ameliorate the mechanical properties of MoAlB.

Download Full-text

First-Principles Study on Al/Al3Hf Heterogeneous Nucleation Interface

Science of Advanced Materials ◽

10.1166/sam.2021.3947 ◽

2021 ◽

Vol 13 (5) ◽

pp. 787-793

Author(s):

Ziming Zhuo ◽

Hongkui Mao ◽

Yizheng Fu

Keyword(s):

Heterogeneous Nucleation ◽

First Principles ◽

Electronic Structures ◽

Interface Energy ◽

Work Of Adhesion ◽

Electronic Interaction ◽

Stacking Sequence ◽

Covalent Bonds ◽

Heterogeneous Nucleus ◽

Metal Bonds

Using first-principles method, the work of adhesion (Wad) and electronic structure of Al3Hf (001)/Al (001) interface are studied and the mechanism of Al3Hf as enhanced heterogeneous nucleus of α-Al are discussed. The results indicate that Al + Hf-termination interfaces with same stacking sequence and the HCP (Al atom locating on top of the Al3Hf slab) interface with the same termination have maximum Wad and minimum interface energy (yint), and therefore they are more stable ones. It is noteworthy that Al + Hf-terminated interface with HCP is most steady one. The stacking of Al atoms on Al3Hf substrates tend to occur in this way. Besides, electronic structures indicate that Al + Hf-terminated interfaces have stronger electronic interaction than that of Al-terminated ones and the Al-Hf bonds of Al + Hf-terminated interface with HCP stacking tend to covalent bonds, while Al–Al bonds of Al-terminated one are metal bonds. Al3Hf as enhanced heterogeneous nucleation of α-Al are effective from crystallography and thermodynamics.

Download Full-text

The Electronic Structures and Magnetic Properties of Co(endi)2(N3)2

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.217-218.1652 ◽

2011 ◽

Vol 217-218 ◽

pp. 1652-1657

Author(s):

Zhong Long Wang ◽

Hui Jin Xu ◽

Kai Lun Yao

Keyword(s):

Magnetic Properties ◽

First Principles ◽

Electronic Structures ◽

Magnetic Coupling ◽

Ferromagnetic Interaction ◽

Azide Ligand ◽

Weak Interlayer ◽

Spin Delocalization ◽

Magnetic Couplings ◽

First Principles Method

The electronic structures and magnetic properties of the compound Co(endi)2(N3)2 are studied by means of the first-principles method. According to the calculations, there is ferromagnetic interaction in the compound, and the magnetic coupling comes from the spin delocalization effect from Co2+ to the azide ligand. It is found that there is strong intralayer and weak interlayer magnetic couplings in the compound. It also reveals semi-metallically magnetic properties.

Download Full-text

Chemical Bonding and Pseudogap in Zn- and Cd-based Compounds with Complex Hexagonal Structures

MRS Proceedings ◽

10.1557/proc-805-ll4.2 ◽

2003 ◽

Vol 805 ◽

Cited By ~ 1

Author(s):

Y. Ishii ◽

K. Nozawa ◽

T. Fujiwara

Keyword(s):

Fermi Level ◽

Density Of States ◽

Chemical Bonding ◽

First Principles ◽

Electronic Structures ◽

Unit Cell ◽

First Principles Calculations ◽

Electronic Density ◽

Electronic Density Of States ◽

Crystal Orbital

ABSTRACTElectronic structures of hexagonal Zn-Mg-Y and Cd58Y13 compounds are studied by first-principles calculations. Both of the systems show deep pseudogap in the electronic density of states near the Fermi level and considered to be stabilized electronically. To illustrate bonding nature of electronic wavefunctions, the crystal orbital Hamilton population (COHP) is calculated for neighboring pairs of atoms in the unit cell. It is found that the bonding nature is changed from bonding to anti-bonding almost exactly at the Fermi level for Zn-Zn and Cd-Cd bonds. On the contrary, for Zn/Cd-Y bonds, both of the states below and above the pseudogap behave as bonding ones. Possible effects of the p-d hybridization are discussed.

Download Full-text