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.

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.

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.

The n- and p-type thermoelectric response of a semiconducting Co-based quaternary Heusler alloy: a density functional approach

2019 ◽  
Vol 7 (25) ◽  
pp. 7664-7671 ◽  
Author(s):  
Enamullah Enamullah ◽  
Pil-Ryung Cha
Keyword(s):  
Electronic Structure ◽  
Thermoelectric Properties ◽  
Heusler Alloy ◽  
Density Functional ◽  
Transport Theory ◽  
Mechanical Stability ◽  
Functional Approach ◽  
Boltzmann Transport ◽  
Boltzmann Transport Theory ◽  
P Type

In the combined framework of density functional and Boltzmann transport theory, we have systematically studied the electronic structure, mechanical stability and thermoelectric properties of the semiconducting quaternary Heusler alloy, CoFeTiAl.

scholarly journals Exploring the thermoelectric properties of oligo(phenylene-ethynylene) derivatives

Nanoscale ◽  
2020 ◽  
Vol 12 (28) ◽  
pp. 15150-15156
Author(s):  
Hang Chen ◽  
Sara Sangtarash ◽  
Guopeng Li ◽  
Markus Gantenbein ◽  
Wenqiang Cao ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Seebeck Coefficient ◽  
Thermoelectric Properties ◽  
Single Molecule ◽  
Phenylene Ethynylene ◽  
Single Molecule Junctions

Seebeck coefficient measurements provide unique insights into the electronic structure of single-molecule junctions.

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.

A New Challenge of Polymer Thermoelectric Materials as Ecomaterials

2007 ◽  
Vol 539-543 ◽  
pp. 2329-2332 ◽  
Author(s):  
Yoshikazu Shinohara ◽  
Yoshio Imai ◽  
Yukihiro Isoda ◽  
Kentaro Hiraishi ◽  
Hachiro Nakanishi
Keyword(s):  
Electrical Conductivity ◽  
Seebeck Coefficient ◽  
Thermoelectric Properties ◽  
Oxidative Polymerization ◽  
Side Chain ◽  
Side Chains ◽  
Nmr Analysis ◽  
Alkyl Side Chains ◽  
High Seebeck Coefficient ◽  
Polymer Thermoelectric

Typical conductive polymers of poly(3-alkylthiophenes) were synthesized by oxidative polymerization. Polythiophene with no side chain was also electrolyticaly polymerized. Alkyl side chains were CnH2n+1 with n=4, 6, 8, 12. The regioregularity with the HT linkage was larger than 99% based on NMR analysis. We have evaluated the effect of side chain size on the thermoelectric properties of Seebeck coefficient and electrical conductivity. The results were as follows: 1) Seebeck coefficient decreased with an increasing electrical conductivity. 2) High Seebeck coefficient >1mV/K was observed at low electrical conductivity <10-2S/cm. 3) Small side chains, especially no side chain caused higher thermoelectric properties of polythiophene series.

ELECTRICAL CONDUCTING AND THERMOELECTRIC PROPERTIES OF Ba4Na2Nb10O30−Ba3NaLaNb10O30 SYSTEM

1990 ◽  
Vol 04 (10) ◽  
pp. 681-688
Author(s):  
MASAYUKI TSUKIOKA ◽  
YASUO TANOKURA ◽  
MASAZI SHIMAZU ◽  
SHINICHIRO KUROIWA ◽  
SADAO TSUTSUMI
Keyword(s):  
Electrical Resistivity ◽  
Seebeck Coefficient ◽  
Thermoelectric Properties ◽  
Solid Solutions ◽  
Diffraction Measurement ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ceramic Samples ◽  
Electrical Conducting ◽  
P Type

Ceramic samples of BNN-BNLN ( Ba 4 Na 2 Nb 10 O 30− Ba 3 NaLaNb 10 O 30) system were prepared in flowing N 2 gas at about 1410°C, which has been confirmed to have continuous solid solutions over the whole range of BNN-BNLN system by X-ray diffraction measurement. Electrical resistivity and Seebeck coefficient measurements were carried out at temperatures from 77 K to 773 K and from 60 K to 200 K, respectively for the samples of different composition belonging to the BNN-BNLN system. These experiments revealed that all these materials were extrinsic semiconductors and change from p-type semiconductors to n-type during the process of rising temperature.

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.

scholarly journals Получение тонких пленок теллурида висмута на полиимидных подложках методом импульсного лазерного осаждения

2020 ◽  
Vol 54 (3) ◽  
pp. 305
Author(s):  
А.Е. Шупенев ◽  
И.С. Коршунов ◽  
А.Г. Григорьянц
Keyword(s):  
Seebeck Coefficient ◽  
Thermoelectric Properties ◽  
Growth Temperature ◽  
Electrical Power ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
Deposition Method ◽  
Substrate Distance ◽  
Polyimide Substrate ◽  
High Seebeck Coefficient

Abstract The peculiarities of obtaining p -Bi_0.5Sb_1.5Te_3 and n -Bi_2Te_2.7Se_0.3 thin thermoelectric films with a thickness of about 300 nm grown on a polyimide substrate by the pulsed-laser-deposition method are reported. The influence of the growth temperature, pressure and target-to-substrate distance on the film’s thermoelectric properties is investigated. Thermoelectric p - and n -type films exhibit a high Seebeck coefficient of 220 and –200 μV/K and low electrical power factors of 9.7 and 5.0 μW/(cm K^2) respectively due to the relatively high electrical resistances of the films.

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