First-Principles Simulation on Thermoelectric Properties in Low-Dimensional Materials

2016 ◽  
Vol 258 ◽  
pp. 77-80 ◽  
Author(s):  
Koichi Nakamura
Keyword(s):  
Seebeck Coefficient ◽  
Carrier Concentration ◽  
Thermoelectric Properties ◽  
First Principles ◽  
First Principles Calculation ◽  
Absolute Value ◽  
Scale Temperature ◽  
Low Dimensional ◽  
Low Dimensional Materials ◽  
Model Structures

Thermoelectric properties were simulated for low-dimensional atomistic model structures based on first-principles calculation. New methodology about the first-principles simulation on Seebeck coefficient at arbitrary temperature and carrier concentration is presented. Dependence of Seebeck coefficient on scale, temperature, and carrier concentration has been demonstrated for silicon and beta silicon carbide nanowire models. Compared with the corresponding bulk models, a significant increase of the absolute value of Seebeck coefficient can be observed owing to quantum confinement by dimensional reduction. By the simulation with considering the energy dependence of the relaxation time, the Seebeck coefficient from the viewpoint of first principles can be evaluated as a range determined by the scattering constants peculiar to particular scattering processes.

scholarly journals Effect of band structure adjustment based of Cu site on the thermoelectric properties of BiCuSeO

2021 ◽  
Author(s):  
Bo Feng
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Seebeck Coefficient ◽  
Effective Mass ◽  
Valence Band ◽  
Thermoelectric Properties ◽  
Density Of States ◽  
First Principles Calculation ◽  
Temperature Range ◽  
Ti Doping

Abstract The effect of Ti doped at Cu site on the thermoelectric properties of BiCuSeO was studied by experimental method and first principles calculation. The results show that Ti doping can cause the lattice contraction and decrease the lattice constant. Ti doping can increase the band gap and lengthen the Cu/Ti-Se bond, resulting in the decrease of carrier concentration. Ti doping can reduce the effective mass and the Bi-Se bond length, correspondingly improve the carrier mobility. Ti doping can decrease the density of states of Cu-3d and Se-4p orbitals at the top of valence band, but Ti-4p orbitals can obviously increase the density of states at the top of valence band and finally increase the electrical conductivity in the whole temperature range. With the decrease of effective mass, Ti doping would reduce the Seebeck coefficient, but the gain effect caused by the increase of electrical conductivity is more than the benefit reduction effect caused by the decrease of Seebeck coefficient, and the power factor shows an upward trend. Ti doping can reduce Young's modulus, lead to the increase of defect scattering and strain field, correspondingly reduce the lattice thermal conductivity and total thermal conductivity. It is greatly increased for the ZT values in the middle and high temperature range, with the highest value of 1.04 at 873 K.

Thermoelectric Properties of n-type (Bi2Se3)x(Bi2Te3)1-x Crystals Prepared by Zone Melting

2008 ◽  
Vol 368-372 ◽  
pp. 547-549
Author(s):  
Jun Jiang ◽  
Ya Li Li ◽  
Gao Jie Xu ◽  
Ping Cui ◽  
Li Dong Chen
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Seebeck Coefficient ◽  
Carrier Concentration ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Zone Melting ◽  
Chemical Compositions ◽  
Melting Method ◽  
Temperature Range

In the present study, n-type (Bi2Se3)x(Bi2Te3)1-x crystals with various chemical compositions were fabricated by the zone melting method. Thermoelectric properties, including Seebeck coefficient (α), electrical conductivity (σ) and thermal conductivity (κ), were measured in the temperature range of 300-500 K. The influence of the variations of Bi2Te3 and Bi2Se3 content on thermoelectric properties was studied. The increase of Bi2Se3 content (x) caused an increase in carrier concentration and thus an increase of σ and a decrease of α. The maximum figure of merit (ZT = α2σT/κ) of 0.87 was obtained at about 325 K for the composition of 93%Bi2Te3-7%Bi2Se3 with doping TeI4.

Band structure, phonon spectrum, and thermoelectric properties of β-BiAs and β-BiSb monolayers

2020 ◽  
Vol 8 (2) ◽  
pp. 581-590 ◽  
Author(s):  
C. Y. Wu ◽  
L. Sun ◽  
J. C. Han ◽  
H. R. Gong
Keyword(s):  
Band Structure ◽  
Thermoelectric Properties ◽  
First Principles ◽  
Phonon Spectrum ◽  
Transport Theory ◽  
First Principles Calculation ◽  
Boltzmann Transport ◽  
Band Structures ◽  
Boltzmann Transport Theory ◽  
Phonon Spectra

First-principles calculation and Boltzmann transport theory have been combined to comparatively investigate the band structures, phonon spectra, and thermoelectric properties of both β-BiSb and β-BiAs monolayers.

Tetragonal and trigonal Mo2B2 monolayers: two new low-dimensional materials for Li-ion and Na-ion batteries

2019 ◽  
Vol 21 (9) ◽  
pp. 5178-5188 ◽  
Author(s):  
Tao Bo ◽  
Peng-Fei Liu ◽  
Junrong Zhang ◽  
Fangwei Wang ◽  
Bao-Tian Wang
Keyword(s):  
First Principles ◽  
Electronic Structures ◽  
Structure Prediction ◽  
Lattice Dynamics ◽  
Anode Materials ◽  
Crystal Structure Prediction ◽  
Prediction Technique ◽  
Li Ion ◽  
Low Dimensional ◽  
Low Dimensional Materials

In this study, we report two new Mo2B2 monolayers and investigate their stabilities, electronic structures, lattice dynamics, and properties as anode materials for energy storage by using the crystal structure prediction technique and first-principles method.

Thermoelectric properties of polycrystalline Bi2Se3−x by powder compaction sintering

2020 ◽  
Vol 34 (18) ◽  
pp. 2050206
Author(s):  
Ying Zhou ◽  
Zhenhua Ge ◽  
Jun Guo ◽  
Jing Feng
Keyword(s):  
Electrical Conductivity ◽  
Seebeck Coefficient ◽  
Carrier Concentration ◽  
Thermoelectric Properties ◽  
Thermoelectric Materials ◽  
Electrical Transport ◽  
Bulk Material ◽  
Powder Compaction ◽  
Electrical Transport Properties ◽  
X Ray

[Formula: see text] is a [Formula: see text] compound (where Pn = Bi and Sb, Ch = Te, Se, and S), which has attracted increasing attention as a candidate for use in thermoelectric applications. Previous studies demonstrated the advantage of [Formula: see text] thermoelectric materials, despite an inferior thermoelectric performance. Herein, a series of [Formula: see text] ([Formula: see text], 0.10, 0.15, 0.20, and 0.25) thermoelectric materials were prepared by powder compaction sintering. The effects of phase structures and microstructure of the [Formula: see text] bulk material were analyzed by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The thermoelectric properties, including Seebeck coefficient, electrical conductivity, and thermal conductivity, were measured systematically. The results show that carrier concentration increased with decreasing Se content, which in turn affected the electrical transport properties. Low Se contents gave larger power factor (PF) values than the pristine [Formula: see text] sample, the maximum PF value being [Formula: see text] at 320 K for [Formula: see text]. The variation in PF was attributed to the variations in electrical conductivity [Formula: see text] and Seebeck coefficient [Formula: see text] upon optimizing Se content. The [Formula: see text] samples showed an enhanced thermoelectric figure of merit (ZT) with increasing measurement temperature, due to the increased [Formula: see text] value, [Formula: see text], and decreased [Formula: see text]. The [Formula: see text] sample exhibited the highest ZT (0.28) at 575 K, while [Formula: see text] exhibited the lowest ZT (0.14) at 325 K. This indicated that tuning Se content was an effective way to enhance carrier concentration.

Quantum effect enhanced magnetism of C-doped phosphorene nanoribbons: first-principles calculations

2017 ◽  
Vol 19 (41) ◽  
pp. 28354-28359 ◽  
Author(s):  
Xiaolin Cai ◽  
Chunyao Niu ◽  
Yuan-Yao He ◽  
Jianjun Wang ◽  
Zhili Zhu ◽  
...  
Keyword(s):  
First Principles ◽  
Quantum Effect ◽  
First Principles Calculations ◽  
Practical Applications ◽  
Low Dimensional ◽  
Low Dimensional Materials

Manipulating magnetism of low-dimensional materials is of great importance for their practical applications.

Size-dependent strain in fivefold twins of gold

2021 ◽  
Vol 77 (1) ◽  
pp. 93-98
Author(s):  
Hao Wu ◽  
Rong Yu ◽  
Jing Zhu ◽  
Wei Chen ◽  
Yadong Li ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
First Principles ◽  
First Principles Calculations ◽  
Geometrical Constraint ◽  
Size Dependent ◽  
Transmission Electron ◽  
Dependent Strain ◽  
Low Dimensional ◽  
Low Dimensional Materials ◽  
Aberration Corrected

Multiple twinned structures are common in low-dimensional materials. They are intrinsically strained due to the geometrical constraint imposed by the non-crystallographic fivefold symmetry. In this study, the strain distributions in sub-10 nm fivefold twins of gold have been analyzed by combining aberration-corrected transmission electron microscopy and first-principles calculations. Bending of atomic planes has been measured by both experiments and calculations, and its contribution to the filling of the angular gap was shown to be size-dependent.

Thermoelectric properties of PbTe thin films prepared by gas evaporation method

1999 ◽  
Vol 14 (1) ◽  
pp. 209-212 ◽  
Author(s):  
Masatoshi Ito ◽  
Won-Son Seo ◽  
Kunihito Koumoto
Keyword(s):  
Thin Films ◽  
Electrical Conductivity ◽  
Grain Size ◽  
Seebeck Coefficient ◽  
Grain Boundaries ◽  
Carrier Concentration ◽  
Thermoelectric Properties ◽  
Carrier Mobility ◽  
Evaporation Method

PbTe thin films with fine grains were successfully fabricated by the gas evaporation method. Thermoelectric properties, i.e., Seebeck coefficient and electrical conductivity, both decreased with decreasing grain size. This was attributed to the decrease in carrier mobility exceeding the increase in carrier concentration with decreasing grain size. It was clarified that the effects of grain boundaries and of oxidation on carrier mobility are considerably large.

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