Effect of anisotropy on phononic band structure and figure of merit of pentamode metamaterials

2020 ◽  
Vol 127 (12) ◽  
pp. 124903
Author(s):  
Chengxin Cai ◽  
Rong Guo ◽  
Xuemei Wang ◽  
Fuyan Sun ◽  
Zhaohong Wang ◽  
...  
Keyword(s):  
Band Structure ◽  
Figure Of Merit

scholarly journals Analyzing transport properties of p-type Mg2Si–Mg2Sn solid solutions: optimization of thermoelectric performance and insight into the electronic band structure

2019 ◽  
Vol 7 (3) ◽  
pp. 1045-1054 ◽  
Author(s):  
Hasbuna Kamila ◽  
Prashant Sahu ◽  
Aryan Sankhla ◽  
Mohammad Yasseri ◽  
Hoang-Ngan Pham ◽  
...  
Keyword(s):  
Band Structure ◽  
Transport Properties ◽  
Carrier Concentration ◽  
Solid Solutions ◽  
Figure Of Merit ◽  
Electronic Band Structure ◽  
Thermoelectric Performance ◽  
Electronic Band ◽  
P Type ◽  
Insight Into

Figure of merit zT mapping of p-Mg2Si1−xSnx with respect to carrier concentration.

The realization of a high thermoelectric figure of merit in Ge-substituted β-Zn4Sb3 through band structure modification

2012 ◽  
Vol 22 (28) ◽  
pp. 13977 ◽  
Author(s):  
Shanyu Wang ◽  
Xiaojian Tan ◽  
Gangjian Tan ◽  
Xiaoyu She ◽  
Wei Liu ◽  
...  
Keyword(s):  
Band Structure ◽  
Figure Of Merit ◽  
Thermoelectric Figure Of Merit ◽  
Structure Modification ◽  
Thermoelectric Figure

Optical and thermoelectric response of RhTiSb half-Heusler

2019 ◽  
Vol 33 (22) ◽  
pp. 1950247 ◽  
Author(s):  
Besbes Anissa ◽  
Djelti Radouan ◽  
Bestani Benaouda
Keyword(s):  
Refractive Index ◽  
Band Structure ◽  
Absorption Coefficient ◽  
Seebeck Coefficient ◽  
Dielectric Function ◽  
Figure Of Merit ◽  
Large Range ◽  
Ultraviolet Region ◽  
Optical Parameters ◽  
Boltzmann Transport

Structural, electronic, optical and thermoelectric response of the cubic RhTiSb compound is reported using TB-mBJ potential. The calculated results for the band structure and DOS confirm that the RhTiSb is a nonmagnetic (NM) semiconductor with an indirect bandgap of 0.71 eV. The main optical parameters such as dielectric function, absorption coefficient, refractive index and optical reflectivity were estimated for emission upto 14 eV. The RhTiSb half-Heusler exhibits a maximum absorption in the visible and ultraviolet region. By using the Boltzmann transport equations as incorporated in BoltzTraP code, the thermoelectric characteristics were calculated. The main properties which describe the aptitude of material in thermoelectric environment such as Seebeck coefficient and figure of merit were calculated. The high values of figure-of-merit (ZT [Formula: see text] 0.7) were observed in large range of temperature indicating that RhTiSb have a good thermoelectric performance.

scholarly journals Comparative studies on the electronic transport in magnetically quantized low band gap semiconductor system

BIBECHANA ◽  
2020 ◽  
Vol 17 ◽  
pp. 34-41
Author(s):  
S Shrestha ◽  
C K Sarkar
Keyword(s):  
Magnetic Field ◽  
Band Structure ◽  
Band Gap ◽  
Cadmium Telluride ◽  
Figure Of Merit ◽  
Mercury Cadmium Telluride ◽  
Energy Levels ◽  
Transverse Component ◽  
Band Structures ◽  
Low Band Gap

The Q1D system formed by magnetically confined system is attracting attention of researchers in device application because it is capable of over-looking the various techniques of fabrication difficulties and defects created by such fabrication techniques. In the presence of a high magnetic field, the transverse component of the energy dispersion relation gets quantized into various equally spaced energy levels called Landau levels and the motion of the carriers is completely restricted. However, the longitudinal component along the field is still free to move. The mobility of such system is enhanced when a low effective mass semiconductors n-HgCdTe (Mercury Cadmium Telluride) is used. The band structure of n-HgCdTe is found to be nonparabolic due to its low band gap according to Kane [Phadke and Sharma, 1975]. Recent publications, based on experimental verifications of transport coefficient of n-HgCdTe of Chen and Sher [Chen and Sher, 1982] show that the band structure of Mercury Cadmium Telluride (MCT) is more hyperbolic in nature rather than nonparabolic. The author has compared the effect of band structures on the various transport properties of MCT such as mobility, Seebeck coefficient, thermal conductivity, figure of merit (Z) etc. The figure of merit is a very important property of a material to be used in thermoelectric devices, such as cooler, refrigerator etc. The product of Z and temperature i.e. (ZT), a dimensionless quantity is found to be maximum for parabolic band structure and is followed by nonparabolic and hyperbolic band structures for all ranges of variation of temperature as well as magnetic field. Taking the hyperbolic band structure of MCT, the effect of high and low temperature scattering mechanisms on ZT is also observed. BIBECHANA 17 (2020) 34-41

scholarly journals First Principles Study of Thermoelectric Properties of Skutterudites: Ir4Sb12 and Ca0.04Ir4Sb12

2020 ◽  
Vol 6 (2) ◽  
pp. 1-9
Author(s):  
B. Bhattarai ◽  
T. Dahal ◽  
N. P. Adhikari
Keyword(s):  
Band Structure ◽  
Band Gap ◽  
Density Of States ◽  
First Principles ◽  
Figure Of Merit ◽  
Density Functional ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Figure ◽  
Metallic Behavior ◽  
Maximum Value

First – principles calculations to study thermal and electrical properties of pristine and calcium filled skutterudite Ir4Sb12 has been carried out. Density of states (DOS) and band-structure calculations are based on Density Functional Theory (DFT) within Generalized Gradient Approximation (GGA). Transport properties are calculated using BoltzTrap software packages. Volume optimization is carried out on the basis of Murnaghan equation of states. The optimized lattice parameter of pristine Ir4Sb12 is found to be 9.4243 Å and that of calcium filled Ir4Sb12 is found to be 9.4949 Å. Our calculation shows that pristine Ir4Sb12 is a p-type of semiconductor with a narrow PBE-GGA band gap of 0.25 eV. After filling calcium, the band gap is reduced to zero showing the metallic behavior of filled compound. Band structure, density of states, variations of electrical and thermal conductivities with temperature and Seebeck coefficient show that calcium filled Ir4Sb12 has a metallic character. At Fermi level, the maximum value of thermoelectric figure of merit of unfilled Ir4Sb12 compound at temperature 400K is found to be 0.5. At the same temperature thermoelectric figure of merit calcium filled Ca0.04Ir4Sb12 is found to be around 0.03. The maximum value of of Ca filled Ca0.04Ir4Sb12 at 1000K is computed around 0.1.

The Structural, Electronic, Optical and Thermo-Electric Properties of Oxynitride Perovskite CaTaO2N

SPIN ◽  
2020 ◽  
Vol 10 (01) ◽  
pp. 2050007
Author(s):  
K. Hocine ◽  
O. Cheref ◽  
K. Bettine ◽  
D. Rached ◽  
S. Benalia ◽  
...  
Keyword(s):  
Band Structure ◽  
Figure Of Merit ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Structural Parameters ◽  
Electric Properties ◽  
Partial Density ◽  
Full Potential ◽  
Thermo Electric ◽  
Electronic Band

In this study, we carried out ab-initio calculations of structural, electronic, optical and thermo-electric properties of CaTaO2N compound in Pnma orthorhombic structure, using the full-potential linearized augmented plane wave method (FP-LAPW), within the framework of density functional theory (DFT). The calculated structural parameters are found to be in good agreement with the experimental results. Moreover, we have studied the electronic band structure, total and partial density of states in order to explain the origin of band gaps and the nitrogen anion contribution in the valence and the conduction bands. The CaTaO2N band structure has shown a direct band gap in the direction [Formula: see text] (with the value 2.32[Formula: see text]eV). The optical properties represented by the dielectric functions for CaTaO2N compound have revealed that the Pnma structure absorbs the light at a large window in the edge UV-Vis regions. In order to explain the thermo-electric properties, we have calculated Seebeck coefficient, electrical conductivity, thermal conductivity and the factor figure of merit in this temperature range 100–1000 K. The factor figure of mérit (ZT) of CaTaO2N takes a maximum value of 0.775 at [Formula: see text][Formula: see text]K.

Improved Figure of Merit of Cu2SnSe3 via Band Structure Modification and Energy-Dependent Carrier Scattering

2020 ◽  
Vol 12 (17) ◽  
pp. 19693-19700 ◽  
Author(s):  
Hongwei Ming ◽  
Chen Zhu ◽  
Xiaoying Qin ◽  
Jian Zhang ◽  
Di Li ◽  
...  
Keyword(s):  
Band Structure ◽  
Figure Of Merit ◽  
Structure Modification ◽  
Carrier Scattering ◽  
Energy Dependent

Advances in thermoelectric (GeTe) x (AgSbTe2)100-x

2021 ◽  
Author(s):  
Hongxia Liu ◽  
Xinyue Zhang ◽  
Wen Li ◽  
Yanzhong Pei
Keyword(s):  
Band Structure ◽  
Figure Of Merit ◽  
Lattice Thermal Conductivity ◽  
Thermoelectric Generators ◽  
Thermoelectric Figure ◽  
Promising Candidate ◽  
Thermoelectric Transport Properties ◽  
Electronic Performance ◽  
P Type ◽  
Strong Anharmonicity

Abstract The (GeTe) x (AgSbTe2)100-x alloys, also called TAGS-x in short, have long been demonstrated as a promising candidate for thermoelectric applications with successful services as the p-type leg in radioisotope thermoelectric generators for space missions. This largely stems from the complex band structure for a superior electronic performance and strong anharmonicity for a low lattice thermal conductivity. Utilization of the proven strategies including carrier concentration optimization, band and defects engineering, an extraordinary thermoelectric figure of merit, zT, has been achieved in TAGS-based alloys. Here, crystal structure, band structure, microstructure, synthesis techniques and thermoelectric transport properties of TAGS-based alloys, as well as successful strategies for manipulating the thermoelectric performance, are surveyed with opportunities for further advancements. These strategies involved are believed to be in principle applicable for advancing many other thermoelectrics.

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