Thermoelectric Properties of Hot-Pressed Ultra-Fine Particulate Sige Powder Alloys with Inert Additions

1991 ◽  
Vol 234 ◽  
Author(s):  
John S. Beaty ◽  
Jonathan L Rolfe ◽  
Jan W. Vandersande
Keyword(s):  
Thermal Conductivity ◽  
Silicon Nitride ◽  
Thermoelectric Materials ◽  
Phonon Scattering ◽  
Fine Powder ◽  
Fine Particulates ◽  
High Temperature Heat Treatment ◽  
Scattering Centers ◽  
Efficiency Theory ◽  
P Type

ABSTRACTThe objective of the work reported here is to reduce the thermal conductivity of thermoelectric materials in order to improve their figureof- merit and conversion efficiency. Theory predicts that the addition of ultra-fine, inert, phonon-scattering centers to thermoelectric materials will reduce their thermal conductivity [1]. To investigate this prediction, ultra-fine particulates (20Å to 120Å) of silicon nitride have been added to boron doped, p-type, 80/20 SiGe. All of the SiGe samples produced from ultra-fine powder have lower thermal conductivities, than that for standard SiGe, but high temperature heat treatment increases the thermal conductivity back to the value for standard SiGe. However, the SiGe samples with silicon nitride, inert, phonon-scattering centers, retained the lower thermal conductivity after several heat treatments. A reduction of approximately 25% in thermal conductivity has been achieved in these samples.

Phonon Scattering and Thermal Conductivity in p-Type Nanostructured PbTe-BaTe Bulk Thermoelectric Materials

2012 ◽  
Vol 22 (24) ◽  
pp. 5175-5184 ◽  
Author(s):  
Shih-Han Lo ◽  
Jiaqing He ◽  
Kanishka Biswas ◽  
Mercouri G. Kanatzidis ◽  
Vinayak P. Dravid
Keyword(s):  
Thermal Conductivity ◽  
Thermoelectric Materials ◽  
Phonon Scattering ◽  
P Type

THERMOELECTRICITY OF Ca2.9Ce0.1Co4O9+δ BASED NANOCOMPOSITES WITH Cu2O NANOINCLUSION

2013 ◽  
Vol 27 (22) ◽  
pp. 1350108
Author(s):  
FANG JU LI
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Energy Harvesting ◽  
Thermoelectric Properties ◽  
Thermoelectric Materials ◽  
Phonon Scattering ◽  
Temperature Dependent ◽  
Resistivity Measurements ◽  
Carrier Scattering ◽  
Scattering Centers

Ca 2.9 Ce 0.1 Co 4 O 9+δ/x wt% Cu 2 O nanocomposites have been studied as the thermoelectric materials for energy harvesting purpose. We evaluate the thermoelectric properties of the composites through temperature dependent thermopower, thermal conductivity and resistivity measurements. It is found that the introduction of Cu 2 O nanoparticles serves as phonon scattering centers, which reduces the thermal conductivity. The nanoinclusions contribute to a remarkable increase in electrical resistivity due to enhanced carrier scattering. As a result, Cu 2 O nanoinclusions do not succeed in improving ZT of Ca 2.9 Ce 0.1 Co 4 O 9+δ material.

Phase Transformation and Thermoelectric Properties of Sn-Filled/Fe-Doped CoSb3 Skutterudites

2011 ◽  
Vol 312-315 ◽  
pp. 223-228
Author(s):  
Il Ho Kim
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Seebeck Coefficient ◽  
Phonon Scattering ◽  
Induction Melting ◽  
X Ray Diffraction ◽  
Scattering Centers ◽  
Δ Phase ◽  
Increasing Temperature ◽  
P Type

Sn-filled and Fe-doped CoSb3 skutterudites were synthesized by encapsulated induction melting. A single δ-phase was obtained by subsequent annealing, as confirmed by X-ray diffraction. The as-solidified ingot consisted of mixed phases of -CoSb, -CoSb2, δ-CoSb3 and elemental Sb. The phases could be transformed by annealing, and the phases of the as-solidified ingot annealed at 773 K for 24 h transformed to δ-CoSb3. The temperature dependence of the Seebeck coefficient, electrical resistivity and thermal conductivity were examined from 300 K to 700 K. The positive Seebeck coefficient confirmed p-type conduction. The electrical resistivity increased with increasing temperature, which showed that the SnzCo3FeSb12 skutterudite is highly degenerate. The thermal conductivity was reduced by Sn-filling because the filler atoms acted as phonon scattering centers in the skutterudite lattice. The thermoelectric figure of merit was enhanced by Sn filling and its optimum composition was considered to be Sn0.3Co3FeSb12.

Reduced thermal conductivity due to scattering centers in p-type SiGe alloys

1992 ◽  
Author(s):  
John S. Beaty ◽  
Johnathan L. Rolfe ◽  
Jan Vandersande ◽  
Jean-Pierre Fleurial
Keyword(s):  
Thermal Conductivity ◽  
Scattering Centers ◽  
P Type

Approaching the minimum lattice thermal conductivity of p-type SnTe thermoelectric materials by Sb and Mg alloying

2019 ◽  
Vol 64 (14) ◽  
pp. 1024-1030 ◽  
Author(s):  
Tiezheng Fu ◽  
Jiazhan Xin ◽  
Tiejun Zhu ◽  
Jiajun Shen ◽  
Teng Fang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermoelectric Materials ◽  
Lattice Thermal Conductivity ◽  
P Type

Phonon Scattering in Bi2Te3/Sb2Te3 Superlattice

2011 ◽  
Author(s):  
Yaguo Wang ◽  
Xianfan Xu ◽  
Rama Venkatasubramanian
Keyword(s):  
Thermal Conductivity ◽  
Thermoelectric Materials ◽  
Phonon Scattering ◽  
Quantum Confinement Effect ◽  
Theoretical Models ◽  
Heat Transfer Process ◽  
Acoustic Phonons ◽  
Time Resolved ◽  
Hetero Structure ◽  
Phonon Velocity

Thermoelectric materials are characterized with the figure of merit, ZT = S2σT/κ, where T is the temperature, S the Seebeck coefficient, σ the electrical conductivity and κ the thermal conductivity. Many researches have been focused on reducing lattice thermal conductivity through increasing phonon scattering at interfaces. Thin-film superlattices are one of the promising candidates for high ZT thermoelectric materials. Several theoretical models have been used to explain the large ZT in superlattice. One comes from the extra scattering channels at interfaces introduced by the hetero-structure. Another is a result of quantum confinement effect which reduces the phonon group velocity propagating perpendicularly through the superlattice layers through flattening the dispersion curve of acoustic phonons. In this work, ultrafast time-resolved measurements were conducted on Bi2Te3, Sb2Te3 and Bi2Te3/Sb2Te3 superlattice (SL) films to detect coherent acoustic phonons in these materials. Scattering of these phonons is revealed in the Bi2Te3/Sb2Te3 SLs, which comes from the interfaces of the hetero-structure in SL. Also, a decrease of acoustic phonon velocity resulted from folding and flattening of phonons branches is observed. Results show that both interface scattering and the reduced phonon velocity contribute to suppressing the heat transfer process.

scholarly journals Graphene inclusion induced ultralow thermal conductivity and improved figure of merit in p-type SnSe

Nanoscale ◽  
2020 ◽  
Vol 12 (24) ◽  
pp. 12760-12766 ◽  
Author(s):  
Lei Chen ◽  
Weiyao Zhao ◽  
Meng Li ◽  
Guangsai Yang ◽  
Sheik Md Kazi Nazrul Islam ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Figure Of Merit ◽  
Phonon Scattering ◽  
P Type

Polycrystalline SnSe sample with graphene embedded in realized the enhancement of phonon scattering and achieved ultralow thermal conductivity.

scholarly journals Reduction of Lattice Thermal Conductivity in PbTe Induced by Artificially Generated Pores

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Jae-Yeol Hwang ◽  
Eun Sung Kim ◽  
Syed Waqar Hasan ◽  
Soon-Mok Choi ◽  
Kyu Hyoung Lee ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Pore Structure ◽  
Transport Properties ◽  
Thermoelectric Materials ◽  
Thermal Transport ◽  
Lattice Thermal Conductivity ◽  
Phonon Scattering ◽  
Phonon Modes ◽  
Thermal Transport Properties

Highly dense pore structure was generated by simple sequential routes using NaCl and PVA as porogens in conventional PbTe thermoelectric materials, and the effect of pores on thermal transport properties was investigated. Compared with the pristine PbTe, the lattice thermal conductivity values of pore-generated PbTe polycrystalline bulks were significantly reduced due to the enhanced phonon scattering by mismatched phonon modes in the presence of pores (200 nm–2 μm) in the PbTe matrix. We obtained extremely low lattice thermal conductivity (~0.56 W m−1 K−1at 773 K) in pore-embedded PbTe bulk after sonication for the elimination of NaCl residue.

Effect of β-Si3N4 Powder on Thermal Conductivity of Silicon Nitride Ceramics

2015 ◽  
Vol 655 ◽  
pp. 11-16 ◽  
Author(s):  
Xing Li Liu ◽  
Meng Meng Peng ◽  
Xiao Shan Ning ◽  
Yosuke Takahashi
Keyword(s):  
Thermal Conductivity ◽  
Heat Treatment ◽  
High Temperature ◽  
Silicon Nitride ◽  
High Temperature Heat Treatment ◽  
Plasma Sintering ◽  
Nitride Ceramics ◽  
Temperature Heat ◽  
Spark Plasma ◽  
Temperature Heat Treatment

To investigate the influence of β-Si3N4 powder on thermal conductivity of silicon nitride, coarse, fine β-Si3N4 powder and various β-Si3N4/α-Si3N4 ratios of starting powders were adopted to fabricate ceramics by spark plasma sintering at 1600°Cand subsequent high-temperature heat treatment at 1900°C with the sintering additives of Y2O3 and MgO. It is found that with more fine β-Si3N4 powder in the starting powder, β-Si3N4 grains exhibit high thermal conductivity, which is partly resulted from the compaction of β-Si3N4 grains.

scholarly journals Hierarchically nanostructured thermoelectric materials: challenges and opportunities for improved power factors

2020 ◽  
Vol 93 (11) ◽  
Author(s):  
Neophytos Neophytou ◽  
Vassilios Vargiamidis ◽  
Samuel Foster ◽  
Patrizio Graziosi ◽  
Laura de Sousa Oliveira ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Power Factor ◽  
High Power ◽  
Thermoelectric Materials ◽  
Phonon Scattering ◽  
Electronic Device ◽  
Macro Scale ◽  
Challenges And Opportunities ◽  
Recent Developments ◽  
New Generation

Abstract The field of thermoelectric materials has undergone a revolutionary transformation over the last couple of decades as a result of the ability to nanostructure and synthesize myriads of materials and their alloys. The ZT figure of merit, which quantifies the performance of a thermoelectric material has more than doubled after decades of inactivity, reaching values larger than two, consistently across materials and temperatures. Central to this ZT improvement is the drastic reduction in the material thermal conductivity due to the scattering of phonons on the numerous interfaces, boundaries, dislocations, point defects, phases, etc., which are purposely included. In these new generation of nanostructured materials, phonon scattering centers of different sizes and geometrical configurations (atomic, nano- and macro-scale) are formed, which are able to scatter phonons of mean-free-paths across the spectrum. Beyond thermal conductivity reductions, ideas are beginning to emerge on how to use similar hierarchical nanostructuring to achieve power factor improvements. Ways that relax the adverse interdependence of the electrical conductivity and Seebeck coefficient are targeted, which allows power factor improvements. For this, elegant designs are required, that utilize for instance non-uniformities in the underlying nanostructured geometry, non-uniformities in the dopant distribution, or potential barriers that form at boundaries between materials. A few recent reports, both theoretical and experimental, indicate that extremely high power factor values can be achieved, even for the same geometries that also provide ultra-low thermal conductivities. Despite the experimental complications that can arise in having the required control in nanostructure realization, in this colloquium, we aim to demonstrate, mostly theoretically, that it is a very promising path worth exploring. We review the most promising recent developments for nanostructures that target power factor improvements and present a series of design ‘ingredients’ necessary to reach high power factors. Finally, we emphasize the importance of theory and transport simulations for materialoptimization, and elaborate on the insight one can obtain from computational tools routinely used in the electronic device communities. Graphical abstract

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