First-principles study of the structural and electronic properties of Sr1−xMxSi2 (M=Ca and Ba)

2019 ◽  
Vol 33 (07) ◽  
pp. 1950039
Author(s):  
N. Q. Jiang ◽  
Z. J. Chen ◽  
T. H. Chen

We investigated the structural and electronic properties of Sr[Formula: see text]M[Formula: see text]Si2 (M[Formula: see text]=[Formula: see text]Ca and Ba) (x[Formula: see text]=[Formula: see text]0, 0.25, 0.5, 0.75 and 1) by the first-principles calculation in the frame work of density-functional theory. It was found that the structure of Sr[Formula: see text]Ca[Formula: see text]Si2 is evidently compressed with increasing the Ca content. On the other hand, the incorporation of Ba cause the swelling crystal structure. A structure transition for Sr[Formula: see text]M[Formula: see text]Si2 (M[Formula: see text]=[Formula: see text]Ca and Ba) from cubic to tetragonal appear when the doping concentration is 0.5. Band structure calculations indicated that the bandgap decrease or even disappear with increasing Ca atoms, which suggesting the transition from the semiconductor to the metal for SrSi2. Whereas, the semiconducting bandgap increases with the incorporation of Ba atoms. Our results imply that the thermoelectric properties of SrSi2-based alloys can be further enhanced by increasing Ca doping content, Ca-doped SrSi2 is a promising thermoelectric material.

2019 ◽  
Vol 16 (2) ◽  
pp. 77 ◽  
Author(s):  
Muhammad Zamir Mohyedin ◽  
Afiq Radzwan ◽  
Mohammad Fariz Mohamad Taib ◽  
Rosnah Zakaria ◽  
Nor Kartini Jaafar ◽  
...  

Bi2Se3 is one of the promising materials in thermoelectric devices and very useful out of environmental concern due to its efficiency to perform at room temperature. Based on the first-principles calculation of density functional theory (DFT) by using CASTEP computer code, structural and electronic properties of Bi2Se3 were investigated. The calculation is conducted within the exchange-correlation of local density approximation (LDA) and generalized gradient approximation within the revision of Perdew-Burke-Ernzerhof (GGA-PBE) functional. It was found that the results are consistent with previous works of theoretical study with small percentage difference. LDA exchange-correlation functional method is more accurate and have a better agreement than GGA-PBE to describe the structural properties of Bi2Se3 which consist of lattice parameters. LDA functional also shown more accurate electronic structure of Bi2Se3 that consist of band structure and density of states (DOS) which consistent with most previous theoretical works with small percentage difference. This study proves the reliability of CASTEP computer code and show LDA exchange-correlation functional is more accurate in describing the nature of Bi2Se3 compared to the other functionals.


Catalysts ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 94
Author(s):  
Mailing Berwanger ◽  
Rajeev Ahuja ◽  
Paulo Cesar Piquini

First principles density functional theory was used to study the energetic, structural, and electronic properties of HfS 2 and TiS 2 materials in their bulk, pristine monolayer, as well as in the monolayer structure with the adsorbed C, N, and P atoms. It is shown that the HfS 2 monolayer remains a semiconductor while TiS 2 changes from semiconductor to metallic behavior after the atomic adsorption. The interaction with the external atoms introduces localized levels inside the band gap of the pristine monolayers, significantly altering their electronic properties, with important consequences on the practical use of these materials in real devices. These results emphasize the importance of considering the interaction of these 2D materials with common external atomic or molecular species.


2014 ◽  
Vol 510 ◽  
pp. 33-38 ◽  
Author(s):  
F.W. Badrudin ◽  
M.S.A. Rasiman ◽  
M.F.M. Taib ◽  
N.H. Hussin ◽  
O.H. Hassan ◽  
...  

Structural and electronic properties of a new fluorine-free cathode material of polyanionichydroxysulfates, LiFeSO4OH withcaminitestructure are studied using first principles density functional theory. From the calculated result, it reveals that antiferromagnetic configuration is more stable compared to ferromagnetic and non-magnetic configuration. Meanwhile, the density of state calculation divulges that this material exhibited large d-d type of band gap and would behave as a Mott-Hubbard insulator. Thus, this behaviour can lead to poor electronic conductivity.


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...


Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1596 ◽  
Author(s):  
Jialin Yan ◽  
Jingjing Xia ◽  
Qinfang Zhang ◽  
Binwen Zhang ◽  
Baolin Wang

Based on the genetic algorithm (GA) incorporated with density functional theory (DFT) calculations, the structural and electronic properties of neutral and charged arsenic clusters Asn (n = 2–24) are investigated. The size-dependent physical properties of neutral clusters, such as the binding energy, HOMO-LUMO gap, and second difference of cluster energies, are discussed. The supercluster structures based on the As8 unit and As2 bridge are found to be dominant for the larger cluster Asn (n ≥ 8). Furthermore, the possible geometric structures of As28, As38, and As180 are predicted based on the growth pattern.


2016 ◽  
Vol 27 (03) ◽  
pp. 1650035 ◽  
Author(s):  
Rezek Mohammad ◽  
Şenay Katırcıoğlu

Structural stability and electronic properties of GaAs[Formula: see text]P[Formula: see text] ([Formula: see text]) nanowires (NWs) in zinc-blende (ZB) ([Formula: see text] diameter [Formula: see text][Formula: see text]Å) and wurtzite (WZ) ([Formula: see text][Formula: see text]Å) phases are investigated by first-principles calculations based on density functional theory (DFT). GaAs ([Formula: see text]) and GaP ([Formula: see text]) compound NWs in WZ phase are found energetically more stable than in ZB structural ones. In the case of GaAs[Formula: see text]P[Formula: see text] alloy NWs, the energetically favorable phase is found size and composition dependent. All the presented NWs have semiconductor characteristics. The quantum size effect is clearly demonstrated for all GaAs[Formula: see text]P[Formula: see text] ([Formula: see text]) NWs. The band gaps of ZB and WZ structural GaAs compound NWs with [Formula: see text] diameter [Formula: see text][Formula: see text]Å and [Formula: see text][Formula: see text]Å, respectively are enlarged by the addition of concentrations of phosphorus for obtaining GaAs[Formula: see text]P[Formula: see text] NWs proportional to the x values around 0.25, 0.50 and 0.75.


2014 ◽  
Vol 28 (26) ◽  
pp. 1450204 ◽  
Author(s):  
Fayyaz Hussain ◽  
M. Imran ◽  
Y. Q. Cai ◽  
Hafeez Ullah ◽  
Abdul Shakoor ◽  
...  

Bulk ZnO has traditionally been regarded as multifunctional materials for energy and optoelectronics applications. Recently, exploring this material at the nanoscale has been reported and seeking a proper substrate is highly desired. In this work, the structural and electronic properties of graphene like ZnO two-dimensional (2D) monolayer are investigated by first principles calculation based on density functional theory. The alignment of the valence and conduction bands of ZnO with the state of Cu substrate is analyzed. Particularly the attention has been focused on the establishment of a Schottky contact and interfacial charge transfer between the 2D ZnO monolayer and Cu substrate. It is predicted that the electronic charges are accumulated on the Zn and O atoms due to d–d hybridization between Cu and Zn . Our study reveals that the significant interaction between the ZnO and Cu can greatly modify the electronic properties of the ZnO and suggests potential applications in nanoelectronic devices.


2012 ◽  
Vol 26 (29) ◽  
pp. 1250151
Author(s):  
Z. H. YU ◽  
C. Y. LI ◽  
H. Z. LIU

Using the first-principles plane wave pseudopotential method, the structural and electronic properties of intermetallic compound SrLiSb have been studied within generalized gradient approximation in the frame of density functional theory. The calculations of lattice parameters are in well agreement with the available experimental data. The geometry optimization results indicated the compressibility of SrLiSb is anisotropic under high pressure. The energy band structure and density of states of SrLiSb were also calculated, indicating that SrLiSb has an electronic phase transition from direct-gap semiconductor to indirect-gap semiconductor at approximate 8 GPa.


2013 ◽  
Vol 703 ◽  
pp. 67-70
Author(s):  
Guo Xiang Chen ◽  
Dou Dou Wang

Calculations have been performed for the structures and electronic properties of GaN nanoribbons with armchair edge (AGaNNRs), using the first-principles projector-augmented wave (PAW) potential within density functional theory (DFT) framework. The lowest unoccupied conduction band (LUCB) and the highest occupied valence band (HOVB) are always separated, representing a semiconductor character for the AGaNNRs. In addition, the majority and minority spin bands are fully superposition and therefore the AGaNNRs are non-magnetic. As the nanoribbons width increase, band gaps of AGaNNRs decrease monotonically and become close to their asymptotic limit of a single layer of GaN sheet.


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