scholarly journals Probing the Structural, elastic, electronic and Thermoelectric Properties of C15-type Laves phase LaCo2: A DFT based ab-initio investigation

2021 ◽  
Vol 67 (4 Jul-Aug) ◽  
Author(s):  
S. Ziri ◽  
L. Blaha ◽  
F. Boukabrime ◽  
A. Maafa ◽  
A. Oughilas ◽  
...  
Keyword(s):  
Lattice Constant ◽  
Thermoelectric Properties ◽  
Density Functional ◽  
Poisson Ratio ◽  
Transport Coefficients ◽  
Laves Phase ◽  
Generalized Gradient ◽  
Large Power ◽  
Cauchy Pressure ◽  
High Seebeck Coefficient

Using first-principles calculations based on density functional theory, structural, elastic, electronic and thermoelectric properties of laves phase LaCo2 intermetallic compound with prototype MgCu2 are stated in this paper. The optimized lattice constant by structural optimization is found to be rationally compatible with the experimental lattice constant.  The Generalized Gradient Approximation (GGA) +Hubbard model was incorporated to evaluate the exact electronic structure. Elastic properties such as, elastic constants, bulk modulus B, shear modulus G, Young’s modulus E, and Poisson ratio ν have been determined using the Voigt–Reuss– Hill approximation. The ductility nature appears in both values of Cauchy pressure and Pugh’s ratio. The band structures and the Cauchy pressure show that the material behaves as metallic. In addition, semi-classical Boltzmann theory is used to verify the applicability of the material for thermoelectric applications. Calculations depict that the spin-up/down transport coefficients are temperature-dependent. It has been found that LaCo2 has a high Seebeck coefficient and therefore a large power factor.

Probing the structural, elastic, electronic and thermoelectric properties of C15-type Laves phase LaCo2: A DFT based ab-initio investigation

2021 ◽  
Vol 67 (4 Jul-Aug) ◽  
pp. 041003
Author(s):  
S. Ziri ◽  
L. Blaha ◽  
F. Boukabrine ◽  
A. Maafa ◽  
A. Oughilas ◽  
...  
Keyword(s):  
Lattice Constant ◽  
Thermoelectric Properties ◽  
Density Functional ◽  
Poisson Ratio ◽  
Transport Coefficients ◽  
Laves Phase ◽  
Generalized Gradient ◽  
Large Power ◽  
Cauchy Pressure ◽  
High Seebeck Coefficient

Using first-principles calculations based on density functional theory, structural, elastic, electronic and thermoelectric properties of laves phase LaCo2 intermetallic compound with prototype MgCu2 are stated in this paper. The optimized lattice constant by structural optimization is found to be rationally compatible with the experimental lattice constant.  The Generalized Gradient Approximation (GGA) +Hubbard model was incorporated to evaluate the exact electronic structure. Elastic properties such as, elastic constants, bulk modulus B, shear modulus G, Young’s modulus E, and Poisson ratio ν have been determined using the Voigt–Reuss– Hill approximation. The ductility nature appears in both values of Cauchy pressure and Pugh’s ratio. The band structures and the Cauchy pressure show that the material behaves as metallic. In addition, semi-classical Boltzmann theory is used to verify the applicability of the material for thermoelectric applications. Calculations depict that the spin-up/down transport coefficients are temperature-dependent. It has been found that LaCo2 has a high Seebeck coefficient and therefore a large power factor.

DFT study of structural, elastic, electronic, magnetic, thermal and transport properties of new multifunctional NiVSn half-Heusler for spintronic and thermoelectric applications

2021 ◽  
pp. 2150202
Author(s):  
Y. Bouldiab ◽  
S. terkhi ◽  
Z. Aziz ◽  
F. Bendahma ◽  
M. A. Bennani ◽  
...  
Keyword(s):  
Transport Properties ◽  
Thermoelectric Properties ◽  
Density Functional ◽  
Extreme Temperature ◽  
Ferromagnetic State ◽  
Debye Model ◽  
Generalized Gradient ◽  
Metallic Behavior ◽  
Half Metallic ◽  
High Seebeck Coefficient

In this work, the first-principles density functional calculations of the structural, elastic, electronic, magnetic, thermal and thermoelectric properties of NiVSn half-Heusler compound are carried out. The exchange and correlation potential are treated by using Generalized Gradient approximation of Perdew, Burke and Ernzerhof (GGA-PBE), GGA plus Tran–Blaha-modified Becke–Johnson (mBJ-GGA) approach and mBJ-GGA+U where U is the Hubbard on-site Coulomb interaction correction (mBJ-GGA+U). Structural calculations revealed that NiVSn is stable in type 1 structure ferromagnetic state. Elastic properties show that our compound is mechanically stable, ductile and anisotropic. The results of the band structures and density of states display a half metallic behavior of NiVSn with an indirect bandgap of 0.476, 0.508 and 0.845 eV by using GGA-PBE, mBJ-GGA, and mBJ-GGA+U, respectively. The total magnetic moment calculated is integer of 1 [Formula: see text]B confirming a half metallic behavior of NiVSn and follows the well-known Slater–Pauling rule ([Formula: see text]); therefore, the studied compound is suitable for application in spintronic fields. The thermodynamic properties such as bulk modulus, the heat capacity, the Debye temperature, and the thermal expansion coefficient are investigated using quasi-harmonic Debye model (QHDM). The thermal results show that NiVSn can be applied in extreme temperature and pressure conditions. The thermoelectric properties are studied employing the BoltzTrap code. The calculated transport properties are very interesting for the spin-down channel with high electrical conductivity, high Seebeck coefficient, and figure of merit value approaching unity. As a result, the half-Heusler alloy NiVSn is a promoter for conventional thermoelectric materials.

scholarly journals Influence of pressure on electro-mechanical properties of SrNbO3: A DFT study

2020 ◽  
Vol 48 (5-6) ◽  
pp. 399-411
Author(s):  
SAAD TARIQ ◽  
ABEEHA BATOOL ◽  
M. A. FARIDI ◽  
M. IMRAN JAMIL ◽  
A. A. MUBARAK ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Lattice Constant ◽  
Density Functional ◽  
Covalent Bond ◽  
Small Contribution ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Generalized Gradient Approximation ◽  
Cauchy Pressure ◽  
Spin Polarized

In the enclosure of density functional theory along with GGA (generalized gradient approximation), incorporated in Wien2k code has been utilized to explore structural, electronic and mechanical properties of SrNbO3 (SNO). It has been found that spin-polarized phase of SNO is most stable at 60 GPa with the calculated lattice constant of 3.801 Å. The calculated lattice constant and bulk modulus at 0 GPa are found to be in agreement with literature. The present calculations predict that SNO is stable and antiferromagnetic in nature up to 60 GPa. The calculated charge density contours and Cauchy pressure depicts majority of the bonding nature between the content atoms of SNO is ionic with a small contribution of covalent bond. The band-gap is found traverse from indirect R-Г gap under 0 GPa to wider direct Г-Г gap under 60 GPa. Furthermore, calculated elastic constants, C11, C12 and C44 suggest that compound is stable up to 60 GPa and exhibits ductile, anisotropic nature. Beneficial electronic and mechanical applications are predicted for SNO that could be used in optoelectronic applications.

Structural, Elastic and Electronic Properties of γ˝ Phase Precipitate in Mg-Gd-Zn Alloy

2019 ◽  
Vol 41 (6) ◽  
pp. 932-932
Author(s):  
Mengmeng Wu Mengmeng Wu ◽  
Rongkai Pan Rongkai Pan ◽  
Jilei Liang Jilei Liang ◽  
Guohai Zhou Guohai Zhou ◽  
Li Ma and Chunyu Zhang Li Ma and Chunyu Zhang
Keyword(s):  
Density Functional ◽  
Elastic Anisotropy ◽  
Poisson Ratio ◽  
Covalent Bond ◽  
Generalized Gradient ◽  
Electronic Density ◽  
Functional Theory ◽  
Full Relaxation ◽  
Principle Density Functional Theory ◽  
Zn Alloy

The γ˝ phase (Mg4GdZn) precipitate in Mg-Gd-Zn alloy was calculated via first-principle density functional theory within the generalized gradient approximation. Through structure optimization of full relaxation, the lattice parameters were theoretically obtained, and the calculated Mg4GdZn is the most energetically stable in view of the formation energy. Independent elastic constants were also calculated, illustrating the calculated Mg4GdZn is mechanically stable. The shear modulus, polycrystalline bulk modulus, Poisson ratio, and Young’s modulus of Mg4GdZn were calculated via the Voigt-Reuss-Hill approximation. Elastic anisotropy and ductility were analyzed in details. Seen from their charge density distribution and electronic density of states, both metallic bond and covalent bond were found in Mg4GdZn.

Ab-initio study of mechanical and thermoelectric properties of topological semimetal: LaAuPb

2021 ◽  
Author(s):  
Megha Goyal ◽  
M.M. Sinha
Keyword(s):  
Thermoelectric Properties ◽  
Density Functional ◽  
Transport Theory ◽  
Poisson Ratio ◽  
Topological Phase ◽  
Boltzmann Transport ◽  
Functional Theory ◽  
Boltzmann Transport Theory ◽  
Material Fabrication ◽  
The Stability

Abstract Heusler compounds are a tuneable class of material with a cubic crystal structure that can serve as a platform to study the topological phase of a material. These materials have numerous technological and scientific applications. So, in the present work, the mechanical, thermodynamical, and thermoelectric properties of LaAuPb in the topological phase have been reported by using density functional theory and Boltzmann transport theory. LaAuPb is mechanically stable, and the Poisson ratio reveals its ductile nature. The specific heat of the proposed compound at room temperature is 73.94 J K-1 mol-1 at constant volume. Debye’s temperature is estimated to be 188.64K. Moreover, the lattice thermal conductivity of the compound is 14.64 W/mK and 3.66 W/mK at 300K and 1200K, respectively. Good thermoelectric response of LaAuPb can be confirmed by its high value of the figure of merit (0.46) at 1200K. Hence, it is a potential material for thermoelectric applications. This work will help future researchers to better understand the stability, nature and behaviour of LaAuPb in material fabrication.

scholarly journals Theoretical study of the phase transitions and electronic structure of (Zr0.5, Mg0.5)N and (Hf0.5, Mg0.5)N

2020 ◽  
Vol 56 (1) ◽  
pp. 305-312
Author(s):  
M. A. Gharavi ◽  
R. Armiento ◽  
B. Alling ◽  
P. Eklund
Keyword(s):  
Electronic Structure ◽  
Seebeck Coefficient ◽  
Thermoelectric Properties ◽  
Solid Solutions ◽  
Rock Salt ◽  
Density Functional ◽  
Configurational Entropy ◽  
Mean Field Approximation ◽  
Random Structure ◽  
High Seebeck Coefficient

Abstract Rock-salt scandium nitride has gained interest due to its thermoelectric properties including a relatively high Seebeck coefficient. This motivates research for other semiconductor materials that exhibit similar electronic structure features as ScN. Using density functional theory calculations, we have studied disordered solid solutions of (Zr0.5, Mg0.5)N and (Hf0.5, Mg0.5)N using the special quasi-random structure model. The results show that within a mean-field approximation for the configurational entropy, the order–disorder phase transformation between the monoclinic LiUN2 prototype structure and the rock-salt cubic random alloy of these mentioned solid solutions occur at 740 K and 1005 K for (Zr0.5, Mg0.5)N and (Hf0.5, Mg0.5)N, respectively. The density-of-states for the two ternary compounds is also calculated and predicts semiconducting behavior with band gaps of 0.75 eV for (Zr0.5, Mg0.5)N and 0.92 eV for (Hf0.5, Mg0.5)N. The thermoelectric properties of both compounds are also predicted. We find that in the range of a moderate change in the Fermi level, a high Seebeck coefficient value at room temperature can be achieved.

First-Principles Study of Structural, Electronic, Optical and Elastic Properties of Cadmium Based Fluoro-Perovskite MCdF3 (M= Rb, Tl)

2019 ◽  
Vol 297 ◽  
pp. 173-186 ◽  
Author(s):  
Abderrahmane Cheriet ◽  
Brahim Lagoun ◽  
Mohamed Halit ◽  
Mourad Zaabat ◽  
Chadli Abdelhakim ◽  
...  
Keyword(s):  
Bulk Modulus ◽  
Density Functional ◽  
Elastic Anisotropy ◽  
Local Density ◽  
Poisson Ratio ◽  
Exchange Potential ◽  
Full Potential ◽  
Generalized Gradient ◽  
Pressure Derivative ◽  
Conduction Bands

This paper presents a theoretical study using the full potential linearized augmented plane wave approach (FP-LAPW) based on the density functional theory (DFT) to predict the structural and electronic properties of RbCdF3 and TlCdF3 compounds. The exchange-correlation potential is treated by the local density approximation (LDA), generalized gradient approximation (GGA) and modified Beck-Johnson exchange potential (mBJ). The calculated structural properties such as the equilibrium lattice parameter, the bulk modulus and its pressure derivative are in good agreement with the available data. The obtained results for the band structure and the density of states (DOS) show that the RbCdF3 (TlCdF3) compound have an indirect band gap of 6.77 and 3.07 eV (5.70 and 3.66 eV) with TB-mBJ and WC method respectively. From the electronic transition from valence conduction bands to conduction bands the optical properties were calculated. The elastic constants were calculated using the energy deformation relationship, from these constants the other mechanical properties such as bulk modulus, shear modulus, Young modulus and Poisson ratio were calculate and comment. Lastly, the elastic anisotropy was discussed.

GGA + U and mBJ + U study of the optoelectronic, magnetic and thermoelectric properties of the SmAlO3 compound with spin–orbit coupling

2016 ◽  
Vol 30 (12) ◽  
pp. 1650078 ◽  
Author(s):  
Sandeep Chettri ◽  
D. P. Rai ◽  
A. Shankar ◽  
R. Khenata ◽  
M. P. Ghimire ◽  
...  
Keyword(s):  
Thermoelectric Properties ◽  
Electronic Structures ◽  
Density Functional ◽  
Orbit Coupling ◽  
Full Potential ◽  
Potential Candidate ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Thermoelectric Efficiency ◽  
Generalized Gradient

The electronic, thermoelectric, optical, and magnetic properties of the samarium aluminate (SmAlO3) compound is studied using the spin-polarized full-potential linearized augmented plane wave (FP-LAPW) method based on the density functional theory (DFT). The exchange and correlation potential is treated with the generalized gradient approximation (GGA) and the Coulomb repulsion ([Formula: see text] Ry) has been calculated theoretically and was used for the GGA[Formula: see text] based approximated electronic structures. Additionally, the modified Becke–Johnson (mBJ) potential was also utilized along with the GGA[Formula: see text] approach for the calculation of the band gap. On the other hand, the optical properties were analyzed with the mBJ[Formula: see text] results and the thermoelectric properties were explained on the basis of the electronic structures and density of states (DOS) with a thermoelectric efficiency of 0.66 at 300 K. The minimum reflectivity at 1.13 eV (which was equal to 1.097 [Formula: see text]m) was found to be in agreement with the experimental results. Further refinements in the electronic structures were obtained by adding the spin–orbit coupling (SOC) interactions to the GGA[Formula: see text] approach, which was then combined with the mBJ approximations. Hence, a conclusion using the combined mBJ[Formula: see text]SOC study indicates that the SmAlO3 compound is a potential candidate for both thermoelectric as well as magnetic devices.

Transport properties of APdCu(Se2)(Se3) (A = K and Rb): new quaternary copper palladium polyselenides

RSC Advances ◽  
2014 ◽  
Vol 4 (39) ◽  
pp. 20102-20113 ◽  
Author(s):  
Sikander Azam ◽  
A. H. Reshak
Keyword(s):  
Density Functional Theory ◽  
Optical Properties ◽  
Electrical Transport ◽  
Density Functional ◽  
Density Functional Theory Calculation ◽  
Transport Coefficients ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Generalized Gradient Approximation ◽  
Theory Calculation

The electronic structure, effective mass, optical properties and electrical transport coefficients of APdCu(Se2)(Se3) (where A = K and Rb), a new quaternary copper palladium polyselenide, were investigated using a density functional theory calculation within a generalized gradient approximation (GGA) plus the Hubbard term (U) (GGA + U).

High Spin Polarization and Thermoelectric Efficiency of Half-Metallic Ferromagnetic CrYSn (Y=Ca, Sr) of Half-Heusler Compounds

SPIN ◽  
2020 ◽  
Vol 10 (02) ◽  
pp. 2050010 ◽  
Author(s):  
B. Bouadjemi ◽  
T. Lantri ◽  
M. Matougui ◽  
M. Houari ◽  
R. Bentata ◽  
...  
Keyword(s):  
Thermoelectric Properties ◽  
Density Functional ◽  
Ferromagnetic State ◽  
Full Potential ◽  
Thermoelectric Efficiency ◽  
Generalized Gradient ◽  
Half Metallic ◽  
Theoretical Predictions ◽  
Thermodynamic Conditions ◽  
High Spin Polarization

In the present work we have performed self-consistent ab-initio calculation using the full-potential linearized augmented plane-wave method (FP-LAPW), based on the density functional theory (DFT) as implemented in the Wien2k code to study the structural, electronic, magnetic, thermodynamic and thermoelectric properties of the half-heusler compound CrYSn ([Formula: see text], Sr) using generalized gradient approximation (GGA) described by Perdew–Burke–Ernzerhof (PBE), GGA+U and the modified Beck–Johnson correction (mBJ), the obtained results show that the compound is stable in the ferromagnetic state (FM) in [Formula: see text] phase on one hand and has a half-metallic character (metallic nature in spin up channel and semiconductor one in spin down channel with an indirect gap) on the other hand thus, the compound is a good candidate for spintronic applications, moreover it shows a very interesting thermoelectric predisposition in the minority spin or spin down channel at room temperature consisting of a very high Seebeck coefficient, high electrical conductivity and figure of merit near unity for the two compounds. The thermodynamic properties of CrCaSn and CrSrSn compounds using Gibbs code are studied for the first time. This study showed that these compounds can be used in extreme thermodynamic conditions. Since no experimental data were reported until now concerning this compound, our theoretical predictions of electronic, thermodynamic and thermoelectric properties are likely to be experimentally verified.

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