Defect Clustering and Nanostructure Formation in PbTe-based Bulk Thermoelectrics

Phonon Scattering ◽

Pair Interaction ◽

Interaction Energies ◽

Thermoelectric Figure ◽

Ionic Model ◽

Pb Ions ◽

Mc Simulation

AbstractIn recent years, LAST-m (AgPbmSbTem+2) and related materials have emerged as potential high performance high temperature thermoelectrics. One example is LAST-18. When optimally doped, this compound has thermoelectric figure of merit ZT=1.7 at 700K. This large ZT is most likely due to the low lattice thermal conductivity, caused by phonon scattering from nanostructures. These nanostructures involve clustering and ordering of Ag, Sb, and Pb ions. The origin of these nanostructures has been studied using Monte Carlo (MC) simulation of an ionic model and ab initio studies of pair interaction energies. Effects of these substitutions on the band structure near the gap and their implications on transport properties are briefly discussed.

Thermal Conductivity of Zn4−xCdxSb3 Solid Solutions

MRS Proceedings ◽

10.1557/proc-478-103 ◽

1997 ◽

Vol 478 ◽

Cited By ~ 20

Author(s):

T. Caillat ◽

A. Borshchevsky ◽

J. -P. Fleurial

Keyword(s):

Thermal Conductivity ◽

High Performance ◽

Figure Of Merit ◽

State Of The Art ◽

Thermoelectric Figure ◽

Jet Propulsion ◽

P Type ◽

Electrical Conductors

Abstractβ-Zn4Sb3 was recently identified at the Jet Propulsion Laboratory as a new high performance p-type thermoelectric material with a maximum dimensionless thermoelectric figure of merit ZT of 1.4 at a temperature of 673K. A usual approach, used for many state-of-the-art thermoelectric materials, to further improve ZT values is to alloy β-Zn4Sb3 with isostructural compounds because of the expected decrease in lattice thermal conductivity. We have grown Zn4−xCdxSb3 crystals with 0.2≤x<1.2 and measured their thermal conductivity from 10 to 500K. The thermal conductivity values of Zn4−xCdxSb3 alloys are significantly lower than those measured for β-Zn4Sb3 and are comparable to its calculated minimum thermal conductivity. A strong atomic disorder is believed to be primarily at the origin of the very low thermal conductivity of these materials which are also fairly good electrical conductors and are therefore excellent candidates for thermoelectric applications.

Vacancy Phonon Scattering and Thermoelectric Properties in In2Te3–SnTe Compounds

Materials Science Forum ◽

10.4028/www.scientific.net/msf.650.126 ◽

2010 ◽

Vol 650 ◽

pp. 126-131 ◽

Cited By ~ 5

Author(s):

Hong Fu ◽

Peng Zhan Ying ◽

J.L. Cui ◽

Y.M. Yan ◽

X.J. Zhang

Keyword(s):

Thermal Conductivity ◽

Point Defects ◽

Figure Of Merit ◽

Phonon Scattering ◽

Chemical Compositions ◽

Thermoelectric Figure ◽

Solid Solution Formation ◽

Solution Formation

Solid solution formation is a common and effective way to reduce the lattice thermal conductivity for thermoelectric materials because of additional phonon scattering by point defects and grain boundaries. In the present work we prepared In2Te3–SnTe compounds using a mild solidification technique and evaluated their thermoelectric properties in the temperature range from 318705 K. Measurements reveal that the transport properties are strongly dependent on the chemical composition  In2Te3 content, and lattice thermal conductivity significantly reduces above a minimum In2Te3 concentration, which can possibly be explained by an introduction of the vacancy on the indium sublattice and periodical vacancy planes. The highest thermoelectric figure of merit ZT of 0.19 can be achieved at 705 K, and a big improvement of In2Te3 based alloys would be expected if a proper optimization to the chemical compositions and structures were made.

Influence of Pd Doping on Electrical and Thermal Properties of n-Type Cu0.008Bi2Te2.7Se0.3 Alloys

Materials ◽

10.3390/ma12244080 ◽

2019 ◽

Vol 12 (24) ◽

pp. 4080 ◽

Cited By ~ 2

Author(s):

Se Yun Kim ◽

Hyun-Sik Kim ◽

Kyu Hyoung Lee ◽

Hyun-jun Cho ◽

Sung-sil Choo ◽

...

Keyword(s):

Thermal Conductivity ◽

Thermal Properties ◽

Carrier Concentration ◽

Figure Of Merit ◽

Phonon Scattering ◽

Energy Conversion Efficiency ◽

Thermoelectric Figure ◽

Pd Doping ◽

Effect Of Pd

Doping is known as an effective way to modify both electrical and thermal transport properties of thermoelectric alloys to enhance their energy conversion efficiency. In this project, we report the effect of Pd doping on the electrical and thermal properties of n-type Cu0.008Bi2Te2.7Se0.3 alloys. Pd doping was found to increase the electrical conductivity along with the electron carrier concentration. As a result, the effective mass and power factors also increased upon the Pd doping. While the bipolar thermal conductivity was reduced with the Pd doping due to the increased carrier concentration, the contribution of Pd to point defect phonon scattering on the lattice thermal conductivity was found to be very small. Consequently, Pd doping resulted in an enhanced thermoelectric figure of merit, zT, at a high temperature, due to the enhanced power factor and the reduced bipolar thermal conductivity.

First-principles prediction of structural stability and thermoelectric properties of SrGaSnH

RSC Advances ◽

10.1039/d0ra09757h ◽

2021 ◽

Vol 11 (6) ◽

pp. 3304-3314

Author(s):

Enamul Haque ◽

Mizanur Rahaman

Keyword(s):

Thermal Conductivity ◽

Structural Stability ◽

First Principles ◽

Figure Of Merit ◽

Phonon Scattering ◽

Thermoelectric Figure

Weak anharmonicity: the weak anharmonicity leads to weak phonon scattering in SrGaSnH. Thus, SrGaSnH intrinsically possesses a high lattice thermal conductivity (kl).. Such large κl dramatically reduces the thermoelectric figure of merit.

Low-Temperature Thermoelectric Properties of Zn4Sb3 Prepared by Hot Pressing

Materials Science Forum ◽

10.4028/www.scientific.net/msf.510-511.1070 ◽

2006 ◽

Vol 510-511 ◽

pp. 1070-1073 ◽

Cited By ~ 3

Author(s):

Il Ho Kim ◽

J.B. Park ◽

Tae Whan Hong ◽

Soon Chul Ur ◽

Young Geun Lee ◽

...

Keyword(s):

Thermal Conductivity ◽

Hot Pressing ◽

Figure Of Merit ◽

Phonon Scattering ◽

Total Thermal Conductivity ◽

Thermoelectric Figure ◽

Scattering Centers

Zn4Sb3 was successfully produced by a hot pressing technique, and its thermoelectric properties were investigated in the temperature range from 4K to 300K. The Seebeck coefficient, electrical conductivity, thermal conductivity, and thermoelectric figure of merit showed a discontinuity in variation at 242K, indicating the α-Zn4Sb3 to β-Zn4Sb3 phase transformation. Lattice thermal conductivity was found to be dominant in the total thermal conductivity of Zn4Sb3. Therefore, it is expected that thermoelectric properties can be improved by reducing the lattice thermal conductivity inducing phonon scattering centers.

Realizing a 14% single-leg thermoelectric efficiency in GeTe alloys

Science Advances ◽

10.1126/sciadv.abf2738 ◽

2021 ◽

Vol 7 (19) ◽

pp. eabf2738

Author(s):

Zhonglin Bu ◽

Xinyue Zhang ◽

Bing Shan ◽

Jing Tang ◽

Hongxia Liu ◽

...

Keyword(s):

High Performance ◽

Figure Of Merit ◽

High Efficiency ◽

Phonon Scattering ◽

Waste Heat ◽

Chemical Diffusion ◽

Thermoelectric Device ◽

Thermoelectric Efficiency ◽

Good Service ◽

Thermoelectric Figure

GeTe alloys have recently attracted wide attention as efficient thermoelectrics. In this work, a single-leg thermoelectric device with a conversion efficiency as high as 14% under a temperature gradient of 440 K was fabricated on the basis of GeTe-Cu2Te-PbSe alloys, which show a peak thermoelectric figure of merit (zT) > 2.5 and an average zT of 1.8 within working temperatures. The high performance of the material is electronically attributed to the carrier concentration optimization and thermally due to the strengthened phonon scattering, the effects of which all originate from the defects in the alloys. A design of Ag/SnTe/GeTe contact successfully enables both a prevention of chemical diffusion and an interfacial contact resistivity of 8 microhm·cm2 for the realization of highly efficient devices with a good service stability/durability. Not only the material’s high performance but also the device’s high efficiency demonstrated the extraordinariness of GeTe alloys for efficient thermoelectric waste-heat recovery.

Review of the Thermoelectric Properties in Nanostructured Fe2VAl

Metals ◽

10.3390/met8110864 ◽

2018 ◽

Vol 8 (11) ◽

pp. 864 ◽

Cited By ~ 7

Author(s):

Eric Alleno

Keyword(s):

Thermal Conductivity ◽

Figure Of Merit ◽

Phonon Scattering ◽

High Pressure Torsion ◽

Thermoelectric Figure ◽

Plasma Sintering ◽

Average Grain Size

Besides alloying, nanostructuring was implemented to improve the thermoelectric properties in Fe2VAl. This Heusler alloy indeed displays a thermoelectric figure of merit too small for applications (ZT ~ 0.1 at 300 K) which is caused by a large lattice thermal conductivity (λL = 27 W·m−1·K−1 at 300 K). The effect of nanostructuring on the microstructure and on the thermoelectric properties of alloyed Fe2VAl are therefore reviewed. By mechanical alloying followed by spark plasma sintering, the average grain size (D) was decreased to D ~ 300–400 nm in Fe2VAl0.9Si0.1, Fe2VAl0.9Si0.07Sb0.03, Fe2V1.05Al0.95, and Fe2V0.9W0.1Al. As expected, phonon scattering at the numerous grain boundaries lead to a strong decrease in the lattice thermal conductivity, which reached values as small as λL = 3.3 W·m−1·K−1. However, in all the reviewed examples, the thermoelectric figure of merit (ZT) is only marginally or not even improved when comparing to non-nanostructured samples because the electrical resistivity also increases upon nanostructuring. A significantly improved ZT = 0.3 at 500 K was only recently observed in severely deformed Fe2VAl0.95Ta0.05 by high pressure torsion because the very fine microstructure (D ~ 100 nm) strongly enhanced the thermal conductivity reduction.

Ultralow lattice thermal conductivity of chalcogenide perovskite CaZrSe3 contributes to high thermoelectric figure of merit

npj Computational Materials ◽

10.1038/s41524-019-0253-5 ◽

2019 ◽

Vol 5 (1) ◽

Author(s):

Eric Osei-Agyemang ◽

Challen Enninful Adu ◽

Ganesh Balasubramanian

Keyword(s):

Thermal Conductivity ◽

Figure Of Merit ◽

Density Functional ◽

Phonon Scattering ◽

Mean Free Path ◽

Boltzmann Transport ◽

Phonon Modes ◽

Thermoelectric Figure

AbstractAn emerging chalcogenide perovskite, CaZrSe3, holds promise for energy conversion applications given its notable optical and electrical properties. However, knowledge of its thermal properties is extremely important, e.g. for potential thermoelectric applications, and has not been previously reported in detail. In this work, we examine and explain the lattice thermal transport mechanisms in CaZrSe3 using density functional theory and Boltzmann transport calculations. We find the mean relaxation time to be extremely short corroborating an enhanced phonon–phonon scattering that annihilates phonon modes, and lowers thermal conductivity. In addition, strong anharmonicity in the perovskite crystal represented by the Grüneisen parameter predictions, and low phonon number density for the acoustic modes, results in the lattice thermal conductivity to be limited to 1.17 W m−1 K−1. The average phonon mean free path in the bulk CaZrSe3 sample (N → ∞) is 138.1 nm and nanostructuring CaZrSe3 sample to ~10 nm diminishes the thermal conductivity to 0.23 W m−1 K−1. We also find that p-type doping yields higher predictions of thermoelectric figure of merit than n-type doping, and values of ZT ~0.95–1 are found for hole concentrations in the range 1016–1017 cm−3 and temperature between 600 and 700 K.

High-Performance of Half-Heusler MNiSn (M=Hf,Zr) Single-Phase Thermoelectric Alloys Fabricated using Optical Floating Zone Melting

MRS Proceedings ◽

10.1557/proc-0886-f09-02 ◽

2005 ◽

Vol 886 ◽

Cited By ~ 4

Author(s):

Yoshisato Kimura ◽

Tomoya Kuji ◽

Akihisa Zama ◽

Yasufumi Shibata ◽

Yoshinao Mishima

Keyword(s):

High Performance ◽

Figure Of Merit ◽

Single Phase ◽

Zone Melting ◽

Floating Zone ◽

Thermoelectric Figure ◽

Micro Cracks ◽

Solidification Defects ◽

First Time

ABSTRACTWe have succeeded to grow almost single-phase of Half-Heusler intermetallic compounds MNiSn, where M = (Hfx,Zr1−x) and x varies from 0 to 1, for the first time by directional solidification using optical floating zone melting (OFZ). Thermoelectric power and electrical resistivity can be dramatically improved since OFZ process effectively reduces solidification defects such as micro-cracks and cavities as well as unfavorable coexisting phases. Dimensionless thermoelectric figure of merit, ZT, of OFZ (Hf,Zr)NiSn alloys can be improved effectively by lowering the lattice thermal conductivity through the solid solution effects due to the substitution of Hf and Zr with each other. The maximum ZT value of 0.9 is achieved in (Hf0.5Zr0.5)NiSn at 963 K.

Influence of multi-sintering on the thermoelectric properties of Bi2Sr2Co2Oy ceramics

Modern Physics Letters B ◽

10.1142/s0217984920500190 ◽

2019 ◽

Vol 34 (02) ◽

pp. 2050019 ◽

Cited By ~ 2

Author(s):

Y. Zhang ◽

M. M. Fan ◽

C. C. Ruan ◽

Y. W. Zhang ◽

X.-J. Li ◽

...

Keyword(s):

Thermal Conductivity ◽

Figure Of Merit ◽

Phonon Scattering ◽

Sintered Sample ◽

Thermoelectric Figure ◽

The Third ◽

Ceramic Samples ◽

Optimum Formula

[Formula: see text] ceramic samples have a structure similar to phonon glass electronic crystals, and their thermoelectric properties can be effectively adjusted through repeated grinding and sintering. The results show that multi-sintering can make their grain refined and increase their grain boundary, which will effectively increase density and phonon scattering. Finally, multi-sintering can reduce the resistivity and thermal conductivity, thus obviously improve thermoelectric figure of merit [Formula: see text] of [Formula: see text]. The optimum [Formula: see text] value of 0.26 is achieved at 923 K by the third sintered sample.