Design and evaluation of n-type Si1-xGex as a thermoelectric-conversion material

2007 ◽  
Vol 1044 ◽  
Author(s):  
Tomohiro Imai ◽  
Tsutomu Iida ◽  
Yuki Miyata ◽  
Takashi Itoh ◽  
Hiroki Funashima ◽  
...  
Keyword(s):  
Seebeck Coefficient ◽  
Thermoelectric Power ◽  
Electronic Band Structure ◽  
Local Density ◽  
Band Structure Calculation ◽  
Full Potential ◽  
Electronic Band ◽  
Thermoelectric Conversion ◽  
High Seebeck Coefficient ◽  
Flapw Method

AbstractSi1-xGex alloys show the high power generating efficiency as a thermoelectric- conversion material. We evaluate the thermoelectric power of the n-type SiGe system on the basis of the first principles calculations. The electronic-band-structure calculation is performed using all-electron full-potential linearized augmented-plane-wave (FLAPW) method within the local density approximation (LDA). The Seebeck coefficient is analyzed by the Bloch-Boltzmann equation. We find that the ordered rhombohedral SiGe has high Seebeck coefficient in comparison with zincblende SiGe. The efficiency of the thermoelectric power in Si1-xGex is gained by the local atomic configuration rather than the Ge concentration.

Study and Design for High Thermoelectric Properties for AgxTeyTlz Compound with First Principle Band Calculation

2010 ◽  
Vol 74 ◽  
pp. 15-21
Author(s):  
Hiroki Funashima ◽  
Noriaki Hamada
Keyword(s):  
Electronic Band Structure ◽  
Local Density ◽  
Band Structure Calculation ◽  
Full Potential ◽  
First Principles Calculations ◽  
Electronic Band ◽  
Augmented Plane Wave ◽  
Plane Wave Method ◽  
Augmented Plane Wave Method ◽  
Linearized Augmented Plane Wave

Recently it was reported that AgxTeyTz shows extremely low thermal conductivity, and high power generating efficiency as a thermoelectric conversion material[1]. We evaluate the seebeck coefficient on basis of the first principles calculations. The electronic band structure calculation is performed using all-electron full-potential linearized augmented plane-wave method(FLAPW) within the local density approximation(LDA). The seebeck coefficent is analyzed by Bloch-Boltzmann equation. In this paper, we find that AgTeTl and AgTe2Tl3 are better thermoelectric material among AgxTeyTlz.

Structural, electronic and elastic properties of the B2-ScM (M =Au, Hg and Tl) intermetallic compounds: Ab initio calculations

2015 ◽  
Vol 04 (04) ◽  
pp. 1550020
Author(s):  
Ahmad A. Mousa ◽  
Jamil M. Khalifeh
Keyword(s):  
Mechanical Properties ◽  
Bulk Modulus ◽  
Intermetallic Compounds ◽  
Elastic Constants ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Local Density ◽  
Full Potential ◽  
Generalized Gradient ◽  
Electronic Band

Structural, electronic, elastic and mechanical properties of ScM (M[Formula: see text][Formula: see text][Formula: see text]Au, Hg and Tl) intermetallic compounds are studied using the full potential-linearized augmented plane wave (FP-LAPW) method based on the density functional theory (DFT), within the generalized gradient approximation (GGA) and the local density approximation (LDA) to the exchange-correlation approximation energy as implemented in the Wien2k code. The ground state properties including lattice parameters, bulk modulus and elastic constants were all computed and compared with the available previous theoretical and experimental results. The lattice constant was found to increase in contrast to the bulk modulus which was found to decrease with every substitution of the cation (M) starting from Au till Tl in ScM. Both the electronic band structure and density-of-states (DOS) calculations show that these compounds possess metallic properties. The calculated elastic constants ([Formula: see text], [Formula: see text] and [Formula: see text] confirmed the elastic stability of the ScM compounds in the B2-phase. The mechanical properties and ductile behaviors of these compounds are also predicted based on the calculated elastic constants.

Ab initio study of structural, mechanical, thermal and electronic properties of perovskites Sr(Li,Pd)H3

2016 ◽  
Vol 30 (04) ◽  
pp. 1650003 ◽  
Author(s):  
S. Benlamari ◽  
S. Amara Korba ◽  
S. Lakel ◽  
H. Meradji ◽  
S. Ghemid ◽  
...  
Keyword(s):  
Bulk Modulus ◽  
Electronic Properties ◽  
Elastic Constants ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Local Density ◽  
Velocity Variation ◽  
Full Potential ◽  
Generalized Gradient ◽  
Electronic Band

The structural, elastic, thermal and electronic properties of perovskite hydrides SrLiH3 and SrPdH3 have been investigated using the all-electron full-potential linear augmented plane wave (FP-LAPW) method based on the density functional theory (DFT). For the exchange-correlation potential, local-density approximation (LDA) and generalized gradient approximation (GGA) have been used to calculate theoretical lattice parameters, bulk modulus, and its pressure derivative. The present results are in good agreement with available theoretical and experimental data. The three independent elastic constants [Formula: see text], [Formula: see text] and [Formula: see text] are also reported. From electronic band structure and density of states (DOSs), it is found that SrLiH3 is an insulator characterized by an indirect gap of 3.48 eV, while SrPdH3 is metallic with a calculated DOSs at Fermi energy of 0.745 states/eV-unit cell. Poisson’s ratio [Formula: see text], Young’s modulus (E), shear modulus (G), anisotropy factor (A), average sound velocities [Formula: see text] and density [Formula: see text] of these compounds are also estimated for the first time. The Debye temperature is deduced from the average sound velocity. Variation of elastic constants and bulk modulus of these compounds as a function of pressure is also reported. Pressure and thermal effects on some macroscopic properties are predicted using the quasi-harmonic Debye model.

Theoretical Prediction of the Structural, Elastic, Electronic and Thermodynamic Properties of Binary CoP3 and Ternary FeCoP3 Skutterudites Materials

SPIN ◽  
2020 ◽  
Vol 10 (02) ◽  
pp. 2050011
Author(s):  
Riadh Zouablia ◽  
Ghlamallah Benabdellah ◽  
Mohamed Mokhtari ◽  
Said Hiadsi
Keyword(s):  
Thermodynamic Properties ◽  
Ternary Alloy ◽  
Electronic Band Structure ◽  
Binary Compound ◽  
Debye Model ◽  
Band Structure Calculation ◽  
Full Potential ◽  
Pressure Derivative ◽  
Electronic Band ◽  
The Impact

The structural, elastic, electronic and thermodynamic properties of skutterudite binary compound CoP3 and the ternary alloy FeCoP3 were investigated by using the full-potential linearized augmented plane-wave plus local orbitals method within the approximation GGA-PBEsol functional. The computed lattice constants, bulk moduli and the pressure derivative of the bulk moduli at the equilibrium are in good agreement with the published experimental data. The brittleness and ductility of these materials were studied by the analysis of the elastic constants and other mechanical parameters, where we have found that both CoP3 and FeCoP3 are ductile materials. The electronic band structure calculation, using the modified Becke-Johnson potential (TB-mBJ), shows that the skutterudite binary compound CoP3 at equilibrium, present a narrow indirect bandgap of 0.524[Formula: see text]eV where the ternary alloy FeCoP3 is a metal behavior. Finally, we investigated the impact of pressure [Formula: see text] and temperature [Formula: see text] on the lattice parameters, heat capacities [Formula: see text], Debye temperatures [Formula: see text] and the entropies [Formula: see text] using the quasi-harmonic Debye model.

ELECTRONIC AND OPTICAL PROPERTIES OF BaO, BaS, BaSe, BaTe AND BaPo COMPOUNDS UNDER HYDROSTATIC PRESSURE

2009 ◽  
Vol 23 (26) ◽  
pp. 3065-3079 ◽  
Author(s):  
S. DRABLIA ◽  
H. MERADJI ◽  
S. GHEMID ◽  
N. BOUKHRIS ◽  
B. BOUHAFS ◽  
...  
Keyword(s):  
Optical Properties ◽  
Dielectric Function ◽  
Imaginary Part ◽  
Density Functional ◽  
Energy Gap ◽  
Electronic Band Structure ◽  
Local Density ◽  
Full Potential ◽  
Electronic Band ◽  
Electronic And Optical Properties

We have performed first-principle full-potential (linear) augmented plane wave plus local orbital calculations (FP-L/APW + l0) with density functional theory (DFT) in local density approximation (LDA) and generalized gradient approximation (GGA), with the aim to determine and predict the electronic and optical properties of rocksalt BaO , BaS , BaSe , BaTe and BaPo compounds. First we present the main features of the electronic properties of these compounds, where the electronic band structure shows that the fundamental energy gap is indirect (Γ–X) for all compounds except for BaO which is direct (X–X). The different interband transitions have been determined from the imaginary part of the dielectric function. The real and imaginary parts of the dielectric function and the reflectivity are calculated. We have presented the assignment of the different optical transitions existing in these compounds from the imaginary part of the dielectric function spectra with respect to their correspondence in the electronic band. We have also calculated the pressure and volume dependence of the optical properties for these compounds.

scholarly journals DFT COMPUTATION OF THE BAND STRUCTURE AND DENSITY OF STATE FOR ZnO HALITE STRUCTURE USING FHI-aims CODE.

2020 ◽  
Vol 4 (2) ◽  
pp. 490-498
Author(s):  
M. A. Adamu ◽  
K. Lawal ◽  
K. Lawal ◽  
A. Saminu
Keyword(s):  
Band Structure ◽  
Band Gap ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Local Density ◽  
Research Work ◽  
Basis Sets ◽  
Band Structure Calculation ◽  
Density Of State ◽  
Electronic Band

This research work is on Density Functional Theory (DFT) within Local Density Approximation as parameterised by Perdew and Wang (pw-lda).The calculation was performed using Fritz Haber Institute Ab-initio Molecular Simulations (FHI-aims) code based on numerical atomic-centered orbital basis sets. The electronic band structure, density of state (DOS) and band gap energy were calculated for ZnO compound. The band structure and Density of States (DOS) diagrams are plotted from the calculated equilibrium lattice parameters. The experimentally lattice constant values were used to calculate the minimum total energy. The calculated electronic band structure results show that ZnO (Halite) is an indirect semiconductor with energy band gap of 0.89 eV. Hence, the HOMO is -0.863382 eV at L_symmetry point and LUMO is 0.0239417 eV at ᴦ- point. The DOS energy level within the compound shows considerable high state of electron occupation and the DOS observed around the Fermi level at zero level indicate that it has conducting properties. In general, FHI-aims code has shown better accuracy and prediction of band structure calculation within reasonable computational methods.

DFT-BASEDAB INITIOSTUDY OF THE ELECTRONIC AND OPTICAL PROPERTIES OF CESIUM BASED FLUORO-PEROVSKITECsMF3(M = CaANDSr)

2012 ◽  
Vol 26 (32) ◽  
pp. 1250199 ◽  
Author(s):  
M. HARMEL ◽  
H. KHACHAI ◽  
M. AMERI ◽  
R. KHENATA ◽  
N. BAKI ◽  
...  
Keyword(s):  
Optical Properties ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Local Density ◽  
Theoretical Data ◽  
Full Potential ◽  
Generalized Gradient ◽  
Electronic Band ◽  
Electronic And Optical Properties ◽  
Structure Density

Density functional theory (DFT) is performed to study the structural, electronic and optical properties of cubic fluoroperovskite AMF3( A = Cs ; M = Ca and Sr ) compounds. The calculations are based on the total-energy calculations within the full-potential linearized augmented plane wave (FP-LAPW) method. The exchange-correlation potential is treated by local density approximation (LDA) and generalized gradient approximation (GGA). The structural properties, including lattice constants, bulk modulus and their pressure derivatives are in very good agreement with the available experimental and theoretical data. The calculations of the electronic band structure, density of states and charge density reveal that compounds are both ionic insulators. The optical properties (namely: the real and the imaginary parts of the dielectric function ε(ω), the refractive index n(ω) and the extinction coefficient k(ω)) were calculated for radiation up to 40.0 eV.

Synthesis, Luminescence and Electronic Band Structure of Al(PO3)3 Crystals

2015 ◽  
Vol 230 ◽  
pp. 73-78 ◽  
Author(s):  
Volodymyr Boyko ◽  
S.G. Nedilko ◽  
Yuriy Hizhnyi ◽  
Vitalii Chornii ◽  
Kateryna Terebilenko ◽  
...  
Keyword(s):  
Electronic Band Structure ◽  
Emission Spectra ◽  
Ultra Violet ◽  
Active Role ◽  
Full Potential ◽  
Electronic Band ◽  
Augmented Plane Wave ◽  
Flapw Method ◽  
Phosphate Groups

The crystals of aluminium metaphosphate Al(PO3)3 are synthesized by flux method. The photoluminescence properties of Al(PO3)3 are studied under the vacuum ultra violet (VUV) synchrotron excitations. The electronic structure of Al(PO3)3 crystal is calculated by the full-potential linear-augmented-plane-wave (FLAPW) method. The photoluminescence (PL) emission spectra of of aluminium metaphosphate reveal emission bands in the ultraviolet-blue and in the yellow-red spectral regions. Obtained results point to an active role of the electronic states of phosphate groups in the processes of intrinsic luminescence in Al(PO3)3 crystals.

scholarly journals Band Gap Engineering of Cd1-xBexSe Alloys

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Djillali Bensaid ◽  
Mohammed Ameri ◽  
Nadia Benseddik ◽  
Ali Mir ◽  
Nour Eddine Bouzouira ◽  
...  
Keyword(s):  
Density Functional ◽  
Electronic Band Structure ◽  
Local Density ◽  
Full Potential ◽  
Electronic Band ◽  
Band Gap Engineering ◽  
Lattice Constants ◽  
Optical Dielectric Constant ◽  
Lmto Method ◽  
Optical Dielectric

The structural and electronic properties of the ternary Cd1-xBexSe alloys have been calculated using the full-potential linear muffin-tin-orbital (FP-LMTO) method based on density functional theory within local density approximation (LDA). The calculated equilibrium lattice constants and bulk moduli are compared with previous results. The concentration dependence of the electronic band structure and the direct and indirect band gaps are investigated. Moreover, the refractive index and the optical dielectric constant for Cd1-xBexSe are studied. The thermodynamic stability of the alloys of interest is investigated by means of the miscibility. This is the first quantitative theoretical prediction to investigate the effective masses, optical and thermodynamic properties for Cd1-xBexSe alloy, and still awaits experimental.

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