scholarly journals First-principles calculation of atomic structure, stability and electronic structure of TaB2/SiC interface

2020 ◽  
Author(s):  
Gong Cheng ◽  
Yuqing Xiong ◽  
Hui Zhou ◽  
Yanchun He ◽  
Kaifeng Zhang ◽  
...  
Keyword(s):  
Charge Density ◽  
Atomic Structure ◽  
First Principles ◽  
Dominant Role ◽  
Covalent Bond ◽  
First Principles Calculation ◽  
Work Of Adhesion ◽  
Structure Stability ◽  
Partial Density ◽  
Electronic Interaction

Abstract The atomic structure, interface stability and electronic interaction of TaB2(0001)/SiC(111) interfaces were investigated by first principles study. The study found that the termination atom and stacking position are the key factors affecting the bonding strength and stability of the interface. On the basis of considering work of adhesion (Wad) and interfacial energy (γint), the Ta-TaB2/C-SiC centre-site stacked (Ta CS-C) and B-TaB2/C-SiC center-site stacked (B-CS-C) configurations were recognized as the most stable structures from ten different interface models. Electronic interaction of the two most stable interfaces were revealed by analyzing the charge density distribution, charge density difference and partial density of states (PDOS), and it was found that ionic and metallic bond coexisted in Ta CS-C interface, while covalent bond played a dominant role in B-CS-C interface.

scholarly journals First-Principles Calculations on Atomic and Electronic Properties of Ge/4H-SiC Heterojunction

2018 ◽  
Vol 2018 ◽  
pp. 1-9
Author(s):  
Bei Xu ◽  
Changjun Zhu ◽  
Xiaomin He ◽  
Yuan Zang ◽  
Shenghuang Lin ◽  
...  
Keyword(s):  
Charge Density ◽  
Electronic Properties ◽  
Density Of States ◽  
First Principles ◽  
Density Functional ◽  
First Principles Calculation ◽  
Partial Density ◽  
Total Charge ◽  
Relaxation Energy ◽  
Total Charge Density

First-principles calculation is employed to investigate atomic and electronic properties of Ge/SiC heterojunction with different Ge orientations. Based on the density functional theory, the work of adhesion, relaxation energy, density of states, and total charge density are calculated. It is shown that Ge(110)/4H-SiC(0001) heterointerface possesses higher adhesion energy than that of Ge(111)/4H-SiC(0001) interface, and hence Ge/4H-SiC(0001) heterojunction with Ge[110] crystalline orientation exhibits more stable characteristics. The relaxation energy of Ge(110)/4H-SiC(0001) heterojunction interface is lower than that of Ge(111)/4H-SiC(0001) interface, indicating that Ge(110)/4H-SiC(0001) interface is easier to form at relative low temperature. The interfacial bonding is analysed using partial density of states and total charge density distribution, and the results show that the bonding is contributed by the Ge-Si bonding.

First-principles calculation of W/WC interface: Atomic structure, stability and electronic properties

2015 ◽  
Vol 324 ◽  
pp. 205-211 ◽  
Author(s):  
Na Jin ◽  
Yanqing Yang ◽  
Xian Luo ◽  
Shuai Liu ◽  
Zhiyuan Xiao ◽  
...  
Keyword(s):  
Electronic Properties ◽  
Atomic Structure ◽  
First Principles ◽  
First Principles Calculation ◽  
Structure Stability

Effect of Alloying Elements V, Cr and Ni on the Electronic Structure and Mechanical Properties of FeAl from First-Principles Calculation

2014 ◽  
Vol 887-888 ◽  
pp. 378-383 ◽  
Author(s):  
Yu Chen ◽  
Zheng Jun Yao ◽  
Ping Ze Zhang ◽  
Dong Bo Wei ◽  
Xi Xi Luo ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Electronic Structure ◽  
Elastic Constants ◽  
First Principles ◽  
Density Functional ◽  
Valence Bond ◽  
Ternary Alloys ◽  
First Principles Calculation ◽  
Structure Stability ◽  
Alloying Element

The structure stability, mechanical properties and electronic structures of B2 phase FeAl intermetallic compounds and FeAl ternary alloys containing V, Cr or Ni were investigated using first-principles density functional theory calculations. Several models are established. The total energies, cohesive energies, lattice constants, elastic constants, density of states, and the charge densities of Fe8Al8 and Fe8XAl7 ( X=V, Cr, Ni ) are calculated. The stable crystal structures of alloy systems are determined due to the cohesive energy results. The calculated lattice contants of Fe-Al-X ( X= V, Cr, Ni) were found to be related to the atomic radii of the alloy elements. The calculation and analysis of the elastic constants showed that ductility of FeAl alloys was improved by the addition of V, Cr or Ni, the improvement was the highest when Cr was used. The order of the ductility was as follows: Fe8CrAl7 > Fe8NiAl7 > Fe8VAl7 > Fe8Al8. The results of electronic structure analysis showed that FeAl were brittle, mainly due to the orbital hybridization of the s, p and d state electron of Fe and the s and p state electrons of Al, showing typical characteristics of a valence bond. Micro-mechanism for improving ductility of FeAl is that d orbital electron of alloying element is maily involved in hybridization of FeAl, alloying element V, Cr and Ni decrease the directional property in bonding of FeAl.

scholarly journals First-Principles Calculation of Conductivity of Ce-C Codoped SnO2 Contacts

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Can Ding ◽  
Zhenjiang Gao ◽  
Xing Hu ◽  
Zhao Yuan
Keyword(s):  
Charge Density ◽  
Lattice Constant ◽  
First Principles ◽  
Density Functional ◽  
Energy Levels ◽  
Circuit Breaker ◽  
Enthalpy Change ◽  
First Principles Calculation ◽  
Contact Material ◽  
Electronic Density

The contact is the core element of the vacuum interrupter of the mechanical DC circuit breaker. The electrical conductivity and welding resistance of the material directly affect its stability and reliability. AgSnO2 contact material has low resistivity, welding resistance, and so on. This material occupies an important position of the circuit breaker contact material. This research is based on the first-principles analysis method of density functional theory. The article calculated the lattice constant, enthalpy change, energy band, electronic density of state, charge density distribution, population, and conductivity of Ce, C single-doped, and Ce-C codoped SnO2 systems. The results show that Ce, C single doping, and Ce-C codoping all increase the cell volume and lattice constant. When the elements are codoped, the enthalpy change is the largest, and the thermal stability is the best. It has the smallest bandgap, the most impurity energy levels, and the least energy required for electronic transitions. The 4f orbital electrons of the Ce atom and the 2p orbital electrons of C are the sources of impurity energy near the Fermi level. When the elements are codoped, more impurity energy levels are generated at the bottom of the conduction band and the top of the valence band. Its bandgap is reduced so conductivity is improved. From the charge density and population analysis, the number of free electrons of Ce atoms and C atoms is redistributed after codoping. It forms a Ce-C covalent bond to further increase the degree of commonality of electrons and enhance the metallicity. The conductivity analysis shows that both single-doped and codoped conductivity have been improved. When the elements are codoped, the conductivity is the largest, and the conductivity is the best.

Atomic structure, stability and electronic properties of S(Al2CuMg)/Al interface: A first-principles study

2018 ◽  
Vol 93 ◽  
pp. 329-337 ◽  
Author(s):  
Xingzhi Pang ◽  
Wenchao Yang ◽  
Jianbing Yang ◽  
Mingjun Pang ◽  
Yongzhong Zhan
Keyword(s):  
Electronic Properties ◽  
Atomic Structure ◽  
First Principles ◽  
Structure Stability ◽  
First Principles Study

Gate-tunable superconductivity and charge-density wave in monolayer 1T$'$-MoTe$_2$ and 1T$'$-WTe$_2$

2021 ◽  
Author(s):  
Young-Woo Son ◽  
Jun-Ho Lee
Keyword(s):  
Phase Transitions ◽  
Charge Density ◽  
First Principles ◽  
Charge Density Wave ◽  
Density Wave ◽  
Quantum Spin ◽  
First Principles Calculation ◽  
Calculation Methods ◽  
Electron Doping ◽  
Quantum Spin Hall

Using first-principles calculation methods, we reveal a series of phase transitions as a function of gating or electron doping in monolayered quantum spin Hall (QSH) insulators, 1T$'$-MoTe$_2$ and 1T$'$-WTe$_2$. As...

Site Preference of Refractory Elements in Ni-Based Single-Crystal Superalloys Alloying with Ru: From First Principles

2012 ◽  
Vol 554-556 ◽  
pp. 3-12
Author(s):  
Jian Jun Cui ◽  
Fei Sun ◽  
Jian Xin Zhang
Keyword(s):  
Binding Energy ◽  
Single Crystal ◽  
First Principles ◽  
First Principles Calculation ◽  
Partial Density ◽  
Site Preference ◽  
Strengthening Effect ◽  
Mulliken Population ◽  
Calculation Results ◽  
Partitioning Behavior

A first principles calculation method was used to investigate the site preference of Ruthenium (Ru) at the γ/γ′ interface in Ni-based single-crystal superalloys. The calculation results show that the addition of Ru can decrease the total energy and the binding energy of γ/γ′ interface, which may result in an improved microstructure stability of Ni-based single-crystal superalloys. Moreover, by calculation, it is also found that Ru can stabilize both γ and γ′ phases and have a preference for Ni site at the coherent γ/γ′ interface. When Ru substitutes the central Ni at the γ/γ′ interface, a reverse partitioning of W, Re and Cr occurs; while the partitioning behavior of Mo is not affected. The influence of Ru on the partitioning behavior of W, Re and Cr in γ′-Ni3Al was studied by Dmol3 calculation as well. The calculation results show that W, Re and Cr have a preference for Ni site in γ′- Ni3Al with Ru alloying. When Ru substitutes the central Ni atom, the site preference of W, Re and Cr varies accordingly. Furthermore, electronic structure analysis of γ/γ′ interface and γ′-Ni3Al in terms of Mulliken population and partial density of states (PDOS) was performed to understand the alloying mechanism of Ru in Ni-based single-crystal superalloys. The results show that the strengthening effect of Ru alloying is mainly due to the reduction in binding energy of Ru as well as a p-orbital hybridization between Ru and the host atoms.

First-Principles Study on Al/Al3Hf Heterogeneous Nucleation Interface

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.

Theoretical Studies of the Atomic and Electronic Structure of Mercury/Aluminium Oxide Interface

2011 ◽  
Vol 255-260 ◽  
pp. 2972-2976 ◽  
Author(s):  
Ping He ◽  
Jiang Wu ◽  
Xiu Min Jiang ◽  
Nai Chao Chen
Keyword(s):  
Charge Density ◽  
Density Functional ◽  
Covalent Bond ◽  
Partial Density ◽  
Oxide Interface ◽  
Functional Theory ◽  
Adsorption Sites ◽  
Interacting Electrons ◽  
Strong Covalent Bond ◽  
Evolution Tendency

Density-functional theory (DFT) theory is conducted for the structural and electronic features at the Hg/Al2O3 interface by the analysis of optimal structural geometry, partial density of states (PDOS) and difference charge density. The two adsorption sites of on-top and hollow locations according to the symmetry is adopted to construct the associated interfacial models between Hg atom and free surface. The calculated studies show that the oxygen atoms near Hg atom in the Al2O3 surface, for both on-top and hollow sites, have the gathering effect by shifting toward Hg atom. But their interacting electrons at the interface exhibit different statues in terms of the PDOS analysis that there have no evolution tendency to form the bond between associated O and Hg atoms at the on-top site; and the occurrence of Hg-5d and O-2p overlapping orbitals reveals the strong covalent bond existed at the interface. The PDOS curves show that Al atom in the surface is not liable to contribute to the formation of corresponding bonds by mixing its electrons with Hg atom. Meanwhile, the calculated results derived from difference charge density are in good agreement with the PDOS analysis. The calculated results support some advanced atomic investigation on design a new sorbent refined from fly gas, especially improving the mercury removal from the flue gas.

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