scholarly journals Stability, Elastic and Electronic Properties of Ta2N by First-Principles Calculations

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 445
Author(s):  
Longpeng Zhu ◽  
Jiong Wang ◽  
Chenchen Dong ◽  
Yong Du ◽  
Shun-Li Shang ◽  
...  

Owing to exploring the influence of the N atoms ordering in Ta2N compounds on their properties, the stability, elastic, and electronic properties of Ta2N compounds (Ta2N-I: P3¯ml and Ta2N-II: P3¯1m) were investigated using first-principles calculations based on density functional theory. Ta2N-II is energetically favorable according to the enthalpy of formation. Elastic constants were employed to reveal the stronger resistance to deformation, but weaker anisotropy, in Ta2N-II. A ductile-brittle transition was found between Ta2N-I (ductile) and Ta2N-II (brittle). The partial density of states showed a stronger orbital hybridization of Ta-d and N-p in Ta2N-II, resulting in stronger covalent bonding. The charge density difference illustrated the interaction of the Ta-N bond and electron distribution of Ta2N.

2019 ◽  
Author(s):  
Henrik Pedersen ◽  
Björn Alling ◽  
Hans Högberg ◽  
Annop Ektarawong

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.


RSC Advances ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 952-957 ◽  
Author(s):  
Konstantina Iordanidou ◽  
Michel Houssa ◽  
Clas Persson

Using first principles calculations based on density functional theory the impact of hole doping on the magnetic and electronic properties of two dimensional PtS2 is studied.


2019 ◽  
Author(s):  
Henrik Pedersen ◽  
Björn Alling ◽  
Hans Högberg ◽  
Annop Ektarawong

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.


Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1640 ◽  
Author(s):  
Yangqi Ji ◽  
Xiaoli Yuan

The elastic properties and electronic properties of MxNy (M = Ti, Zr) TiN, Ti2N, Zr3N4, ZrN with different structures have been investigated using density functional theory. Through the calculation of the elastic constants, it was found that all of these structures meet the mechanical stability except for ZrN with space group P63mc. Their mechanical properties are studied by a comparison of various parameters. The stiffness of TiN is larger than that of ZrN with space group Fm 3 ¯ m. Ti2N’s stiffness with space group I41/amdz is larger than Ti2N with space group P42/mnm. Zr3N4’s stiffness with space group Pnam is largest in three structures of Zr3N4. TiN, Ti2N and ZrN are non-central force, Zr3N4 is central force. TiN and ZrN with space group Fm 3 ¯ m are brittle, and TiN is brittler than ZrN with space group Fm 3 ¯ m. The two kinds of Ti2N are brittle and Ti2N with space group I41/amdz is larger. Three structures of Zr3N4 are tough and Zr3N4 with space group I 4 ¯ 3d is the toughest. Meanwhile, the electronic properties of TiN, Ti2N, Zr3N4 and ZrN were calculated, possible superconducting properties of the studied materials were predicted.


RSC Advances ◽  
2018 ◽  
Vol 8 (70) ◽  
pp. 39976-39982 ◽  
Author(s):  
E. Unsal ◽  
F. Iyikanat ◽  
H. Sahin ◽  
R. T. Senger

Herein, we carried out first-principles calculations based on density functional theory to investigate the effects of surface functionalization with hydrogen atoms on structural, dynamical and electronic properties of Cu2Si monolayer.


2015 ◽  
Vol 817 ◽  
pp. 690-697
Author(s):  
Yong Hua Duan ◽  
Yong Sun ◽  
Ming Jun Peng

The stability and electronic properties of Mg2Pb (100), (110) and (111) surfaces were investigated by using the first-principles density functional theory (DFT) method. The calculated results showed that the orders of relaxation and surface energy are |∆d15(111)| < |∆d15(110)| < |∆d15(100)| andEsurf(100) >Esurf(110) >Esurf(111), respectively, indicating that Mg2Pb (111) surface is the most stable among these three low index surfaces. The Density of states (DOS) of Mg2Pb surfaces are mainly dominated by Pb-6, Mg-3s, and 2porbitals in the band ranging from-5 eV to Fermi level. It can be further obtained from results of the DOS and the charge density difference that Mg2Pb (111) surface is more stable than Mg2Pb (100) and (110) surfaces. The Mg2Pb (111) surface is the thermodynamically most favorable over all of the range of.


Author(s):  
Enesio Marinho Jr ◽  
Pedro Alves da Silva Autreto

Graphene-based materials (GBMs) are a large family of materials that have attracted great interest due to potential applications. In this work, we applied first-principles calculations based on density functional theory...


Author(s):  
Xia Yun He ◽  
Jing Li ◽  
Lin Tao ◽  
Shuai Nie ◽  
Timing Fang ◽  
...  

Compared with pure metal oxides, heterojunction greatly changes the response to gas by the synergistic effect of interface. In this work, density functional theory was used to reveal the adsorption...


2019 ◽  
Author(s):  
Henrik Pedersen ◽  
Björn Alling ◽  
Hans Högberg ◽  
Annop Ektarawong

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.


2018 ◽  
Vol 08 (01) ◽  
pp. 1820002 ◽  
Author(s):  
Xiaobin Liu ◽  
Wenxiu Que ◽  
Yucheng He ◽  
Huanfu Zhou

The electronic properties of Cu-doped lithium niobate (LiNbO3) systems are investigated by first-principles calculations. In this work, we focus on substitutionally Cu[Formula: see text]Li-doped LiNbO3 system with cuprous and cupric doping, which corresponds to the Li[Formula: see text]Cu[Formula: see text]NbO3 and Li[Formula: see text]Cu[Formula: see text]NbO3 [abbreviated as (Li, Cu I)NbO3 and (Li, Cu II)NbO3]. The density functional theory (DFT) calculations show that the electronic property of LiNbO3 is completely different from (Li, Cu I)NbO3 and (Li, Cu II)NbO3. The calculated band structure and density of state (DOS) of (Li, Cu I)NbO3 show a small band gap of 1.34[Formula: see text]eV and the top of valance band (VB) is completely composed of a doping energy level originating from Cu 3d filled orbital. However, the calculated band structure and DOS of (Li, Cu II)NbO3 show a relatively large band gap of 2.22[Formula: see text]eV and the top of VB is mainly composed of Cu 3d unfilled orbital and O 2p orbital.


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