scholarly journals Thermoelectric Properties of Sb-S System Compounds from DFT Calculations

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4707
Author(s):  
Hailong Yang ◽  
Pascal Boulet ◽  
Marie-Christine Record
Keyword(s):  
Seebeck Coefficient ◽  
Thermoelectric Properties ◽  
Electronic Structures ◽  
Density Functional ◽  
Lattice Thermal Conductivity ◽  
Dimensional Structure ◽  
Functional Theory ◽  
One Dimensional ◽  
Shed Light

By combining density functional theory, quantum theory of atoms in molecules and transport properties calculations, we evaluated the thermoelectric properties of Sb-S system compounds and shed light on their relationships with electronic structures. The results show that, for Sb2S3, the large density of states (DOS) variation induces a large Seebeck coefficient. Taking into account the long-range weak bonds distribution, Sb2S3 should exhibit low lattice thermal conductivity. Therefore, Sb2S3 is promising for thermoelectric applications. The insertion of Be atoms into the Sb2S3 interstitial sites demonstrates the electrical properties and Seebeck coefficient anisotropy and sheds light on the understanding of the role of quasi-one-dimensional structure in the electron transport. The large interstitial sites existing in SbS2 are at the origin of phonons anharmonicity which counteracts the thermal transport. The introduction of Zn and Ga atoms into these interstitial sites could result in an enhancement of all the thermoelectric properties.

Electronic structure of the thermoelectric materials PbTe and AgPb18SbTe20 from first-principles calculations

2010 ◽  
Vol 25 (6) ◽  
pp. 1030-1036 ◽  
Author(s):  
Pengxian Lu ◽  
Zigang Shen ◽  
Xing Hu
Keyword(s):  
Band Structure ◽  
Thermoelectric Properties ◽  
First Principles ◽  
Electronic Structures ◽  
Density Functional ◽  
Partial Density ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Scanning Transmission ◽  
Linearized Augmented Plane Wave

To investigate the effects of substituting Ag and Sb for Pb on the thermoelectric properties of PbTe, the electronic structures of PbTe and AgPb18SbTe20 were calculated by using the linearized augmented plane wave based on the density-functional theory of the first principles. By comparing the differences in the band structure, the partial density of states (PDOS), the scanning transmission microscope, and the electron density difference for PbTe and AgPb18SbTe20, we explained the reason from the aspect of electronic structures why the thermoelectric properties of AgPb18SbTe20 could be improved significantly. Our results suggest that the excellent thermoelectric properties of AgPb18SbTe20 should be attributed in part to the narrowing of its band gap, band structure anisotropy, the much extrema and large DOS near Fermi energy, as well as the large effective mass of electrons. Moreover, the complex bonding behaviors for which the strong bonds and the weak bonds are coexisted, and the electrovalence and covalence of Pb–Te bond are mixed should also play an important role in the enhancement of the thermoelectric properties of the AgPb18SbTe20.

scholarly journals Giant magnetoresistance and spin Seebeck coefficient in zigzag α-graphyne nanoribbons

Nanoscale ◽  
2014 ◽  
Vol 6 (19) ◽  
pp. 11121-11129 ◽  
Author(s):  
Ming-Xing Zhai ◽  
Xue-Feng Wang ◽  
P. Vasilopoulos ◽  
Yu-Shen Liu ◽  
Yao-Jun Dong ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Seebeck Coefficient ◽  
Thermoelectric Properties ◽  
Green's Function ◽  
Density Functional ◽  
Function Method ◽  
Giant Magnetoresistance ◽  
Functional Theory ◽  
Non Equilibrium Green’S Function ◽  
Non Equilibrium

We investigate the spin-dependent electric and thermoelectric properties of ferromagnetic zigzag α-graphyne nanoribbons (ZαGNRs) using density-functional theory combined with non-equilibrium Green's function method.

scholarly journals Piezoresistivity of InAsP Nanowires: Role of Crystal Phases and Phosphorus Atoms in Strain-Induced Channel Conductances

Molecules ◽  
2019 ◽  
Vol 24 (18) ◽  
pp. 3249 ◽  
Author(s):  
In Kim ◽  
Han Seul Kim ◽  
Hoon Ryu
Keyword(s):  
Density Functional Theory ◽  
Electronic Structures ◽  
Density Functional ◽  
Experimental Studies ◽  
Atomistic Simulations ◽  
Wurtzite Phase ◽  
Strong Electron ◽  
Functional Theory ◽  
Crystal Phases

Strong piezoresistivity of InAsP nanowires is rationalized with atomistic simulations coupled to Density Functional Theory. With a focal interest in the case of the As(75%)-P(25%) alloy, the role of crystal phases and phosphorus atoms in strain-driven carrier conductance is discussed with a direct comparison to nanowires of a single crystal phase and a binary (InAs) alloy. Our analysis of electronic structures presents solid evidences that the strong electron conductance and its sensitivity to external tensile stress are due to the phosphorous atoms in a Wurtzite phase, and the effect of a Zincblende phase is not remarkable. With several solid connections to recent experimental studies, this work can serve as a sound framework for understanding of the unique piezoresistive characteristics of InAsP nanowires.

Thermoelectric Properties of Sm Doped CaMnO3 Using Density Functional Theory Method

2020 ◽  
Vol 1010 ◽  
pp. 334-338
Author(s):  
Abdullah Chik ◽  
Ruhiyuddin Mohd Zaki ◽  
Akeem Adekunle Adewale ◽  
Faizul Che Pa ◽  
Yeoh Cheow Keat
Keyword(s):  
Thermal Conductivity ◽  
Density Functional Theory ◽  
High Temperature ◽  
Seebeck Coefficient ◽  
Temperature Dependence ◽  
Band Gap ◽  
Thermoelectric Properties ◽  
Density Functional ◽  
Electronic Band ◽  
Functional Theory

The electronic structure and thermoelectric properties of CaMnO3 doped with 8% and 17% f block element Sm using first principles calculations and semi-classic Boltzmann theory were presented in this paper. The G-type AFM phase is most stable among five phases for CaMnO3, however, with 8% and 17% Sm doping, these compounds became nonmagnetic phases. CaMnO3 calculated electronic band structure shows an indirect band gap of 0.523 eV, which is underestimated by the density functional theory (DFT) calculations but the band gap explains the semiconducting behavior. However, with 8% and 17% Sm doping, the electronic bandstructure of these compounds exhibit metallic behavior, with Sm and Mn 3d electrons contributing to conduction band, increasing the magnitude of conductivity for doped compounds. All temperature dependence Seebeck coefficient plots show n-typed conduction for all compound with reduced magnitude of Seebeck coefficient for doped compounds. The temperature dependence thermal conductivity plot shows overall thermal conductivity is reduced in Sm doped compound. CaMnO3 with 17% Sm doping exhibit much higher ZT of 0.32 at 800 K showing enhanced thermoelectric properties at high temperature and suitability or high temperature energy conversion devices.

STRUCTURE AND DYNAMICS OF Al TRIMER ON Al(111) SURFACE

1999 ◽  
Vol 06 (05) ◽  
pp. 787-792
Author(s):  
C. M. CHANG ◽  
C. M. WEI
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Diffusion Processes ◽  
Center Of Mass ◽  
Density Functional Theory Calculations ◽  
Dimensional Structure ◽  
Functional Theory ◽  
One Dimensional ◽  
Structure And Dynamics ◽  
Diffusion Mechanisms

Trimer is the smallest cluster that can have a one-dimensional or a two-dimensional structure on fcc (111) surface. Using first-principles density-functional-theory calculations, the structural and dynamical properties of Al trimer on Al(111) surface have been studied in detail. Al trimer on Al(111) surface has four close-packed (compact) triangular configurations, two linear configurations, and some other noncompact triangular configurations. The close-packed triangular trimers are more stable than the noncompact triangular trimers as well as the linear trimers. For the dynamics of Al trimer on Al(111) surface, the diffusion processes are much more complicated than the adatom and dimer diffusions. There are three different kinds of diffusion mechanisms: concerted translations and rotation of compact triangular trimers (the energy barrier, Ed=0.24 eV); back and forth transformation between compact triangular trimers and linear trimers (Ed=0.21 eV); and translation of linear trimers (Ed= 0.28 eV). Among these different mechanisms with similar height of diffusion barriers, the concerted translations of the compact triangular trimers have the longest displacement of the center of mass in each step. Therefore, we expect that the long-range diffusion of Al trimer on Al(111) surface is dominated by the concerted motion process of the compact triangular trimers.

scholarly journals Revisiting the Electronic Structures and Phonon Properties of Thermoelectric Antimonide-Tellurides: Spin–Orbit Coupling Induced Gap Opening in ZrSbTe and HfSbTe

Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 917
Author(s):  
Souraya Goumri-Said ◽  
Tahani A. Alrebdi ◽  
Engin Deligoz ◽  
Haci Ozisik ◽  
Mohammed Benali Kanoun
Keyword(s):  
Thermoelectric Properties ◽  
Electronic Structures ◽  
Density Functional ◽  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Functional Theory ◽  
Gap Opening ◽  
Dynamical Properties ◽  
Phonon Properties

We report theoretical studies based on density functional theory within spin-orbit coupling to explore electronic structures, lattice dynamical properties of ZrSbTe and HfSbTe. With spin−orbit coupling included, our findings reveal that ZrSbTe and HfSbTe exhibit a semiconducting behavior with narrow indirect band gaps of 0.10 eV, and 0.15 eV, respectively. Besides, the lattice dynamical properties revealed that the explored materials based on antimonide−tellurides are dynamically stable. On the basis of electronic structures, the thermoelectric properties were computed using the Landauer-Buttiker formula by considering both electron and phonon contributions in the transport properties calculation. We employed Green’s-function method based on the Green-Kubo-Mori formula, where the thermoelectric properties such as the electrical conductivity σ and thermopower α were estimated in terms of the correlation functions. The present work could be viewed as a significant amendment of the electronic nature of ZrSbTe and HfSbTe that were reported to be metallic in literature.

Electronic Structures and Thermoelectric Properties of NaCo2O4 Thermoelectric Material

2011 ◽  
Vol 317-319 ◽  
pp. 2051-2055 ◽  
Author(s):  
Qiu Hua Ma ◽  
Qing Wei Wang ◽  
Peng Xian Lu ◽  
Yong Gai Hou
Keyword(s):  
Electrical Conductivity ◽  
Effective Mass ◽  
Thermoelectric Properties ◽  
Thermoelectric Material ◽  
Electronic Structures ◽  
Density Functional ◽  
Energy Gap ◽  
Covalent Bond ◽  
Strongly Correlated ◽  
Functional Theory

The electronic structures of thermoelectric material NaCo2O4 were studied by the first-principles calculations with plane-wave pseudopotential method and generalized approximation (GGA) based on density functional theory (DFT). On the basis of calculation for electronic structures, thermoelectric properties of NaCo2O4 were also investigated in this paper. The reasons for large thermoelectric potential are large effective mass of holes at the top of valence band and 6μB net spin magnetic moment. While high electrical conductivity should be attributed to small effective mass of electrons at the bottom of conduction band, large carrier concentration near the Fermi level and narrowed energy gap. In addition, covalent bond between Co atom and O atom promotes carrier mobility and thus benefits to electrical conductivity. Na1 and Na2 have different effects on the NaCo2O4. Na1 provides local state electrons and yet Na2 provides itinerant-electrons which play important role to strongly correlated system.

scholarly journals DFT Studies on the Electronic Structures of 4-Methoxybenzonitrile Dye for Dye-Sensitized Solar Cell

2013 ◽  
Vol 12 ◽  
pp. 8-22 ◽  
Author(s):  
A. Prakasam ◽  
D. Sakthi ◽  
P.M. Anbarasan
Keyword(s):  
Electron Transfer ◽  
Electronic Structures ◽  
Density Functional ◽  
Hybrid Functional ◽  
Absorption Bands ◽  
Functional Theory ◽  
Dye Sensitizer ◽  
Injection Process ◽  
Electron Transfer Processes

The geometries, electronic structures, polarizabilities and hyperpolarizabilities of organic dye sensitizer 4-methoxybenzonitrile was studied based on Ab Initio HF and Density Functional Theory (DFT) using the hybrid functional B3LYP. Ultraviolet-visible (UV-Vis) spectrum was investigated by Time Dependent DFT (TDDFT). Features of the electronic absorption spectrum in the visible and near-UV regions were assigned based on TDDFT calculations. The absorption bands are assigned to π→π* transitions. Calculated results suggest that the three excited states with the lowest excited energies in 4-methoxybenzonitrile is due to photoinduced electron transfer processes. The interfacial electron transfer between semiconductor TiO2 electrode and dye sensitizer 4-methoxybenzonitrile, is due to an electron injection process from excited dye to the semiconductor’s conduction band. The role of nitro group in 4-methoxybenzonitrile in geometries, electronic structures, and spectral properties were analyzed.

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