Thermal Conductivity Reduction in Nanostructured Semiconductor Using Broad-Band-Phonon Scattering

2004 ◽  
Author(s):  
Woochul Kim ◽  
Pramod Reddy ◽  
Arun Majumdar ◽  
Joshua Zide ◽  
Arthur Gossard ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Power Generation ◽  
Phonon Spectrum ◽  
Electrical Transport ◽  
Phonon Scattering ◽  
Broad Band ◽  
Impedance Mismatch ◽  
Efficient Operation ◽  
Low Thermal Conductivity ◽  
Nanostructured Semiconductor

Low thermal conductivity is essential for efficient operation of thermoelectric/thermionic power generation devices. There have been several attempts to design materials with low thermal conductivity without sacrificing electrical transport. These approaches utilized different mechanisms of phonon scattering, such as acoustic impedance mismatch of the adjacent layers in superlattices or defect scattering of phonons etc [1, 2]. However, each of these approaches scatter phonons only in a particular region of the phonon spectrum. In this paper we present experimental results of the thermal conductivity of epitaxially grown superlattices engineered to take advantage of the various scattering mechanisms to scatter phonons over the entire phonon spectrum.

Effects of the Addition of Rhenium on the Thermoelectric Properties of the AlPdMn Quasicrystalline System

2000 ◽  
Vol 626 ◽  
Author(s):  
A. L. Pope ◽  
R. Gagnon ◽  
R. Schneidmiller ◽  
P. N. Alboni ◽  
R. T. Littleton ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Transport Property ◽  
Periodic Structure ◽  
Thermoelectric Properties ◽  
Electrical Transport ◽  
Room Temperature ◽  
Phonon Scattering ◽  
X Ray ◽  
Low Thermal Conductivity

ABSTRACTPartially due to their lack of periodic structure, quasicrystals have inherently low thermal conductivity on the order of 1 - 3 W/m-K. AlPdMn quasicrystals exhibit favorable room temperature values of electrical conductivity, 500–800 (Ω-cm)-1, and thermopower, 80 μV/K, with respect to thermoelectric applications. In an effort to further increase the thermopower and hopefully minimize the thermal conductivity via phonon scattering, quartenary Al71Pd21Mn8-XReX quasicrystals were grown. X-ray data confirms that the addition of a fourth element does not alter the quasiperiodicity of the sample. Al71Pd21Mn8-XReX quasicrystals of varying Re concentration were synthesized where x had values of 0, 0.08, 0.25, 0.4, 0.8, 2, 5, 6, and 8. Both thermal and electrical transport property measurements have been performed and are reported.

scholarly journals Electrical Transport and Thermoelectric Properties of SnSe–SnTe Solid Solution

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3854 ◽  
Author(s):  
Jun-Young Cho ◽  
Muhammad Siyar ◽  
Woo Chan Jin ◽  
Euyheon Hwang ◽  
Seung-Hwan Bae ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Solid Solution ◽  
Electrical Conductivity ◽  
Single Crystal ◽  
Carrier Concentration ◽  
Electrical Transport ◽  
Lattice Thermal Conductivity ◽  
Phonon Scattering ◽  
Practical Applications ◽  
Defect Sites

SnSe is considered as a promising thermoelectric (TE) material since the discovery of the record figure of merit (ZT) of 2.6 at 926 K in single crystal SnSe. It is, however, difficult to use single crystal SnSe for practical applications due to the poor mechanical properties and the difficulty and cost of fabricating a single crystal. It is highly desirable to improve the properties of polycrystalline SnSe whose TE properties are still not near to that of single crystal SnSe. In this study, in order to control the TE properties of polycrystalline SnSe, polycrystalline SnSe–SnTe solid solutions were fabricated, and the effect of the solid solution on the electrical transport and TE properties was investigated. The SnSe1−xTex samples were fabricated using mechanical alloying and spark plasma sintering. X-ray diffraction (XRD) analyses revealed that the solubility limit of Te in SnSe1−xTex is somewhere between x = 0.3 and 0.5. With increasing Te content, the electrical conductivity was increased due to the increase of carrier concentration, while the lattice thermal conductivity was suppressed by the increased amount of phonon scattering. The change of carrier concentration and electrical conductivity is explained using the measured band gap energy and the calculated band structure. The change of thermal conductivity is explained using the change of lattice thermal conductivity from the increased amount of phonon scattering at the point defect sites. A ZT of ~0.78 was obtained at 823 K from SnSe0.7Te0.3, which is an ~11% improvement compared to that of SnSe.

scholarly journals N-Type Bismuth Telluride Nanocomposite Materials Optimization for Thermoelectric Generators in Wearable Applications

Materials ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1529 ◽  
Author(s):  
Amin Nozariasbmarz ◽  
Jerzy S. Krasinski ◽  
Daryoosh Vashaee
Keyword(s):  
Thermal Conductivity ◽  
Power Generation ◽  
Seebeck Coefficient ◽  
Figure Of Merit ◽  
Microwave Cavity ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Figure ◽  
Efficient Operation ◽  
High Seebeck Coefficient ◽  
Body Heat

Thermoelectric materials could play a crucial role in the future of wearable electronic devices. They can continuously generate electricity from body heat. For efficient operation in wearable systems, in addition to a high thermoelectric figure of merit, zT, the thermoelectric material must have low thermal conductivity and a high Seebeck coefficient. In this study, we successfully synthesized high-performance nanocomposites of n-type Bi2Te2.7Se0.3, optimized especially for body heat harvesting and power generation applications. Different techniques such as dopant optimization, glass inclusion, microwave radiation in a single mode microwave cavity, and sintering conditions were used to optimize the temperature-dependent thermoelectric properties of Bi2Te2.7Se0.3. The effects of these techniques were studied and compared with each other. A room temperature thermal conductivity as low as 0.65 W/mK and high Seebeck coefficient of −297 μV/K were obtained for a wearable application, while maintaining a high thermoelectric figure of merit, zT, of 0.87 and an average zT of 0.82 over the entire temperature range of 25 °C to 225 °C, which makes the material appropriate for a variety of power generation applications.

scholarly journals Ultra-low Thermal Conductivity in Si/Ge Hierarchical Superlattice Nanowire

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Xin Mu ◽  
Lili Wang ◽  
Xueming Yang ◽  
Pu Zhang ◽  
Albert C. To ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Silicon Germanium ◽  
Phonon Scattering ◽  
Low Thermal Conductivity ◽  
Structural Hierarchy ◽  
Si Nanowire ◽  
Hierarchical Structuring ◽  
Simulation Results ◽  
Dynamics Simulations

Abstract Due to interfacial phonon scattering and nanoscale size effect, silicon/germanium (Si/Ge) superlattice nanowire (SNW) can have very low thermal conductivity, which is very attractive for thermoelectrics. In this paper, we demonstrate using molecular dynamics simulations that the already low thermal conductivity of Si/Ge SNW can be further reduced by introducing hierarchical structure to form Si/Ge hierarchical superlattice nanowire (H-SNW). The structural hierarchy introduces defects to disrupt the periodicity of regular SNW and scatters coherent phonons, which are the key contributors to thermal transport in regular SNW. Our simulation results show that periodically arranged defects in Si/Ge H-SNW lead to a ~38% reduction of the already low thermal conductivity of regular Si/Ge SNW. By randomizing the arrangement of defects and imposing additional surface complexities to enhance phonon scattering, further reduction in thermal conductivity can be achieved. Compared to pure Si nanowire, the thermal conductivity reduction of Si/Ge H-SNW can be as large as ~95%. It is concluded that the hierarchical structuring is an effective way of reducing thermal conductivity significantly in SNW, which can be a promising path for improving the efficiency of Si/Ge-based SNW thermoelectrics.

Ultra-low thermal conductivity via interfacial phonon scattering in PbTe hoppercubes/PbTeO3 microrods for thermoelectric applications

2019 ◽  
Vol 799 ◽  
pp. 26-35
Author(s):  
S. Kavirajan ◽  
J. Archana ◽  
M. Omprakash ◽  
S. Harish ◽  
M. Navaneethan ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Phonon Scattering ◽  
Low Thermal Conductivity

Effect of fullerene addition on thermoelectric properties ofn-type skutterudite compound

2007 ◽  
Vol 22 (1) ◽  
pp. 249-253 ◽  
Author(s):  
Takashi Itoh ◽  
Kenta Ishikawa ◽  
Akira Okada
Keyword(s):  
Thermal Conductivity ◽  
Power Generation ◽  
Thermoelectric Properties ◽  
Thermoelectric Materials ◽  
Phonon Scattering ◽  
Grinding Method ◽  
Milling Method ◽  
Compound Matrix ◽  
Skutterudite Compound ◽  
Dispersion Of Nanoparticles

Thermoelectric power generation is a promising method for harnessing waste thermal energy, especially in the temperature range between 500 and 800 K. It is necessary to improve the performance of thermoelectric materials for the realization of the power generation. Dispersion of nanoparticles such as fullerenes is expected to induce phonon scattering that decreases thermal conductivity of materials, and application to thermoelectric materials may lead to improved properties. In the present study, then-type Co0.92Ni0.08Sb2.96Te0.04thermoelectric compound was synthesized, and the thermoelectric properties were evaluated. Furthermore, the fullerene particles were sufficiently mixed with the thermoelectric compound powder by the mechanical grinding method, and influences of the fullerene additions to the compound were investigated. The dispersion of fullerene particles in then-type Co0.92Ni0.08Sb2.96Te0.04compound was conducted through the planetary ball milling method to disentangle agglomerates of the fullerene and to disperse the particles in the thermoelectric compound matrix. The thermal conductivity decreased with an increase in fullerene content, and the maximum in dimensionless figure of meritZTwas 0.62 at 800 K for 1 mass% fullerene addition. This was 28% higher than that of fullerene-free sample.

scholarly journals First-Principles Calculations of Thermal and Electrical Transport Properties of bcc and fcc Dilute Fe–X (X = Al, Co, Cr, Mn, Mo, Nb, Ni, Ti, V, and W) Binary Alloys

Metals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1988
Author(s):  
Yang Lin ◽  
Xiaoyu Chong ◽  
Yingchun Ding ◽  
Yunxuan Zhou ◽  
Mengdi Gan ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Transport ◽  
Lattice Thermal Conductivity ◽  
Phonon Scattering ◽  
High Strength Steels ◽  
High Strength ◽  
Alloying Elements ◽  
Total Thermal Conductivity ◽  
Boltzmann Transport ◽  
Ultra High Strength Steels

The adiabatic shear sensitivity of ultra-high-strength steels is closely related to their thermal conductivity. Therefore, it is essential to investigate the effects of alloying elements on the thermal conductivity of ultra-high-strength steel. In this study, the variation in the scattering behavior of electrons with respect to temperature and the mechanism of three-phonon scattering were considered for obtaining the contributions of electrons and phonons, respectively, to the thermal conductivity of alloys while solving the Boltzmann transport equation. By predicting the effect of ten alloying elements on the electronic thermal conductivity (κe), it was found that, at 1200 K, the doping of iron with Ni and Cr endowed iron with κe values of 24.9 and 25.7 W/m K, respectively. In addition, the prediction for the lattice thermal conductivity (κL), which was performed without considering point defect scattering, indicated that elements such as Al, Co, Mn, Mo, V, and Cr demonstrate a positive effect on the lattice thermal conductivity, with values of 3.6, 3.7, 3.0, 3.1, 3.9, and 3.8 W/m K, respectively. The contribution of κL is only 5–15% of the total thermal conductivity (κtotal). The alloying elements exhibited a similar effect on κtotal and κe. Δκi; the change in thermal conductivity with respect to κ0 owing to the alloying element i was evaluated according to the total thermal conductivity. These values were used to understand the effect of the concentration of alloying elements on the thermal conductivity of iron. The Δκi values of Ni, Co, and W were 6.44, 6.80, and 6.06, respectively, indicating a reduction in the thermal conductivity of iron. This paper provides theoretical guidance for the design of ultra-high-strength steels with a high thermal conductivity.

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