Dense dislocation arrays embedded in grain boundaries for high-performance bulk thermoelectrics

Science ◽  
2015 ◽  
Vol 348 (6230) ◽  
pp. 109-114 ◽  
Author(s):  
Sang Il Kim ◽  
Kyu Hyoung Lee ◽  
Hyeon A Mun ◽  
Hyun Sik Kim ◽  
Sung Woo Hwang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Grain Boundaries ◽  
Lattice Thermal Conductivity ◽  
Phonon Scattering ◽  
Maximum Temperature ◽  
Bismuth Antimony Telluride ◽  
Maximum Temperature Difference ◽  
Full Spectrum ◽  
Dislocation Arrays ◽  
Bulk Alloys

The widespread use of thermoelectric technology is constrained by a relatively low conversion efficiency of the bulk alloys, which is evaluated in terms of a dimensionless figure of merit (zT). ThezTof bulk alloys can be improved by reducing lattice thermal conductivity through grain boundary and point-defect scattering, which target low- and high-frequency phonons. Dense dislocation arrays formed at low-energy grain boundaries by liquid-phase compaction in Bi0.5Sb1.5Te3(bismuth antimony telluride) effectively scatter midfrequency phonons, leading to a substantially lower lattice thermal conductivity. Full-spectrum phonon scattering with minimal charge-carrier scattering dramatically improved thezTto 1.86 ± 0.15 at 320 kelvin (K). Further, a thermoelectric cooler confirmed the performance with a maximum temperature difference of 81 K, which is much higher than current commercial Peltier cooling devices.

EFFECT OF EMBEDDING NANOPARTICLES ON THERMAL CONDUCTIVITY OF CRYSTALLINE SEMICONDUCTORS: PHONON SCATTERING MECHANISM

2009 ◽  
Vol 08 (06) ◽  
pp. 551-556 ◽  
Author(s):  
K. K. CHOUDHARY ◽  
D. PRASAD ◽  
K. JAYAKUMAR ◽  
DINESH VARSHNEY
Keyword(s):  
Thermal Conductivity ◽  
Grain Boundaries ◽  
Lattice Thermal Conductivity ◽  
Present Model ◽  
Phonon Scattering ◽  
Scattering Mechanism ◽  
Temperature Dependent ◽  
Pure Crystal ◽  
Model Hamiltonian ◽  
Heat Carriers

We evolve a theoretical model for quantitative analysis of decrease in thermal conductivity (κ) by embedding ErAs nanoparticles in In0.53Ga0.47As crystalline semiconductors. The lattice thermal conductivity by incorporating the scattering of phonons with defects, grain boundaries, electrons, and phonons in the model Hamiltonian are evaluated. It is noticed that the ErAs nanoparticles provide an additional scattering mechanism for phonons. The embedding of ErAs nanoparticles in In0.53Ga0.47As crystalline semiconductors, the phonon scattering with point defects and grain boundaries become more efficient, which cause in the decrease of thermal conductivity up to half of its value of pure crystal. Conclusively, the temperature dependent of thermal conductivity is determined by competition among the several operating scattering mechanisms for the heat carriers. Numerical analysis of thermal conductivity from the present model shows similar results as those revealed from experiments.

Thermal Conductivity of Nano-Porous Bismuth Antimony Telluride

2010 ◽  
Author(s):  
Saburo Tanaka ◽  
Masayuki Takashiri ◽  
Koji Miyazaki
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Phonon Scattering ◽  
Antimony Telluride ◽  
Bismuth Antimony Telluride ◽  
Porous Thin Films ◽  
Average Grain Size ◽  
Bismuth Antimony ◽  
Bulk Alloys ◽  
Thermal Conductivities

Bismuth antimony telluride (Bi0.4Te3.0Sb1.6) nano-porous thin films have been prepared and measured their thermal conductivities. The thin films exhibit an average grain size of 50 nm and random crystal orientation. The cross-plane thermal conductivity is measured by a differential 3ω method at temperature range from 100 to 300 K, and the determined thermal conductivities are from 0.09 to 0.18 W/(m·K). As compared with bulk alloys at the same atomic composition, the nano-porous thin films exhibit an eightfold reduction in the thermal conductivity. For more detail analysis, the reduction of the thermal conductivity is examined by a simplified phonon gas model on a single crystal of bulk Bi2Te3. The analytical model fairly agreed with the experimental results, and thus we consider that the thermal conductivity is reduced by the strong phonon scattering at the nano-pores.

Thermoelectric Properties of AgBiTe2-Ag2Te Composite

1998 ◽  
Vol 545 ◽  
Author(s):  
Y. Takigawa ◽  
T. Imoto ◽  
T. Sakakibara ◽  
K. Kurosawa
Keyword(s):  
Thermal Conductivity ◽  
Composite Materials ◽  
Grain Boundaries ◽  
Thermoelectric Properties ◽  
Lattice Thermal Conductivity ◽  
Phonon Scattering ◽  
Lattice Vibrations ◽  
Thermoelectric Devices ◽  
Long Wavelength ◽  
Prepared Composite

AbstractWe prepared composite materials of AgBiTe2 with several contents of Ag2Te small-size grains for applications to thermoelectric devices. By enhancing long-wavelength phonon scattering at the grain boundaries, lattice thermal conductivity (thermal conductivity due to lattice vibrations) decreased 30% and thus the thermoelectric characteristics were significantly improved.

Highly enhanced thermoelectric properties of nanostructured Bi2S3 bulk materials via carrier modification and multi-scale phonon scattering

2019 ◽  
Vol 6 (6) ◽  
pp. 1374-1381 ◽  
Author(s):  
Yi Wu ◽  
Qing Lou ◽  
Yang Qiu ◽  
Jun Guo ◽  
Zhi-Yuan Mei ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Grain Boundaries ◽  
Thermoelectric Properties ◽  
Point Defects ◽  
Lattice Thermal Conductivity ◽  
Phonon Scattering ◽  
Bulk Materials ◽  
Multi Scale ◽  
Multiscale Structure ◽  
Strong Scattering

Low lattice thermal conductivity for LaCl3-doped samples is obtained via a multiscale structure and strong scattering by point defects, dislocations and grain boundaries.

Lattice Thermal Conductivity Modelling of a Diatomic Nanoscale Material

2020 ◽  
Vol 10 (5) ◽  
pp. 602-609
Author(s):  
Adil H. Awad
Keyword(s):  
Thermal Conductivity ◽  
Lattice Thermal Conductivity ◽  
Phonon Scattering ◽  
Correction Term ◽  
Nanoscale Material ◽  
New Approach ◽  
Two Samples ◽  
Conductivity Modelling ◽  
Callaway Model

Introduction: A new approach for expressing the lattice thermal conductivity of diatomic nanoscale materials is developed. Methods: The lattice thermal conductivity of two samples of GaAs nanobeam at 4-100K is calculated on the basis of monatomic dispersion relation. Phonons are scattered by nanobeam boundaries, point defects and other phonons via normal and Umklapp processes. Methods: A comparative study of the results of the present analysis and those obtained using Callaway formula is performed. We clearly demonstrate the importance of the utilised scattering mechanisms in lattice thermal conductivity by addressing the separate role of the phonon scattering relaxation rate. The formulas derived from the correction term are also presented, and their difference from Callaway model is evident. Furthermore their percentage contribution is sufficiently small to be neglected in calculating lattice thermal conductivity. Conclusion: Our model is successfully used to correlate the predicted lattice thermal conductivity with that of the experimental observation.

scholarly journals First-principles predictions of low lattice thermal conductivity and high thermoelectric performance of AZnSb (A = Rb, Cs)

RSC Advances ◽  
2021 ◽  
Vol 11 (25) ◽  
pp. 15486-15496
Author(s):  
Enamul Haque
Keyword(s):  
Thermal Conductivity ◽  
Debye Temperature ◽  
Layered Structure ◽  
First Principles ◽  
Lattice Thermal Conductivity ◽  
Phonon Scattering ◽  
Thermoelectric Performance

The layered structure, and presence of heavier elements Rb/Cs and Sb induce high anharmonicity, low Debye temperature, intense phonon scattering, and hence, low lattice thermal conductivity.

scholarly journals Effect of ZnO and SnO2 Nanolayers at Grain Boundaries on Thermoelectric Properties of Polycrystalline Skutterudites

Nanomaterials ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 2270
Author(s):  
Sang-il Kim ◽  
Jiwoo An ◽  
Woo-Jae Lee ◽  
Se Kwon ◽  
Woo Nam ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Atomic Layer Deposition ◽  
Grain Boundaries ◽  
Thermoelectric Properties ◽  
Phonon Scattering ◽  
Atomic Layer ◽  
Deposition Method ◽  
Plasma Sintering ◽  
Layer Deposition ◽  
Atomic Layer Deposition Method

Nanostructuring is considered one of the key approaches to achieve highly efficient thermoelectric alloys by reducing thermal conductivity. In this study, we investigated the effect of oxide (ZnO and SnO2) nanolayers at the grain boundaries of polycrystalline In0.2Yb0.1Co4Sb12 skutterudites on their electrical and thermal transport properties. Skutterudite powders with oxide nanolayers were prepared by atomic layer deposition method, and the number of deposition cycles was varied to control the coating thickness. The coated powders were consolidated by spark plasma sintering. With increasing number of deposition cycle, the electrical conductivity gradually decreased, while the Seebeck coefficient changed insignificantly; this indicates that the carrier mobility decreased due to the oxide nanolayers. In contrast, the lattice thermal conductivity increased with an increase in the number of deposition cycles, demonstrating the reduction in phonon scattering by grain boundaries owing to the oxide nanolayers. Thus, we could easily control the thermoelectric properties of skutterudite materials through adjusting the oxide nanolayer by atomic layer deposition method.

Theory of Thermal Conductivity of Micro- and Nano-structured Materials

2009 ◽  
Vol 1172 ◽  
Author(s):  
Gyaneshwar P. Srivastava
Keyword(s):  
Thermal Conductivity ◽  
Lattice Thermal Conductivity ◽  
Phonon Scattering ◽  
Polycrystalline Diamond ◽  
Comprehensive Treatment ◽  
Si Nanowires ◽  
Quantitative Investigation ◽  
Debye Relaxation ◽  
Structured Materials ◽  
20 Nm

AbstractWe provide a brief discussion of the Boltzmann equation derived Callaway-Debye relaxation time theory of lattice thermal conductivity of micro- and nano-structured materials (of size greater than 20 nm. Incorporated in the theory is a comprehensive treatment of three-phonon scattering events. Using numerical results from this theory, we present a quantitative investigation of the magnitude and temperature variation of the conductivity of CVD polycrystalline diamond films, suspended GaAs nanostructures, Si nanowires, and AlN micro- and nano-ceramics.

Effects of Heat Treatment on Thermal Conductivity of Highly Porous Copper/Silver Systems

2007 ◽  
Author(s):  
Brian A. Murtha ◽  
Anil K. Kulkarni ◽  
Jogender Singh
Keyword(s):  
Thermal Conductivity ◽  
Heat Treatment ◽  
Porous Material ◽  
Grain Boundaries ◽  
Phonon Scattering ◽  
Particle Diffusion ◽  
Conductive Heat ◽  
Material Particle ◽  
Highly Porous ◽  
Highly Porous Material

The phenomenon of sintering has a significant impact on the thermal conductivity of a highly porous material. Particle diffusion greatly reduces the number of grain boundaries that are normally present in porous materials. In turn, fewer grain boundaries imply fewer sites for phonon scattering during conductive heat transfer. Therefore, during heat treatment of a highly porous material, particle diffusion accounts for a changing thermal conductivity. This occurs with no bulk densificiation of the material. In fact, SEM images show that the microstructure of a porous material changes from many individual particles with small pores between the particles to diffused particles with large pores in between large chunks of material. To model such a phenomenon, standard equations were scaled with unitless weighting functions to account for variable microstructures during heating. By weighting standard equations, the effects of microstructure could be more accurately described as a function of porosity and time.

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