Glass-like lattice thermal conductivity and high thermoelectric efficiency in Yb9Mn4.2Sb9

AbstractRecent experimental and theoretical studies have shown that the thermal to electrical power conversion efficiency (as measured by the thermoelectric figure of merit) can be enhanced in nanocomposite materials. Primarily, these efforts to improve the thermoelectric efficiency rely on reducing the lattice thermal conductivity through nanostructuring of the materials or the introduction of a second nanometer-scale phase into the composite material. Here, we show that the inclusion of semimetal nanoparticles into bismuth telluride (Bi2Te3) can result in both an increase in the electronic transport properties (so called "power factor") as well as a decrease in lattice thermal conductivity. The effect of different volume fractions of Bi nanoinclusions (3% and 5%) on the thermal and electrical properties of the composite are reported. A marginal increase in the thermoelectric figure of merit is achieved for 3% metal nanoinclusion, whereas a significant improvement in the figure of merit could be achieved for 5% nanoinclusions in the Bi2Te3 thermoelectric matrix.

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Improvement of Thermoelectric Properties through Reduction of Thermal Conductivity by Nanoparticle Addition and Stoichiometric Change to Mg2Si

MRS Advances ◽

10.1557/adv.2017.507 ◽

2017 ◽

Vol 2 (58-59) ◽

pp. 3637-3643

Author(s):

William T. Yorgason ◽

Arden N. Barnes ◽

Nick Roberts

Keyword(s):

Thermal Conductivity ◽

Lattice Thermal Conductivity ◽

Phonon Scattering ◽

Waste Heat ◽

Mean Free Path ◽

Phonon Transport ◽

Thermoelectric Efficiency ◽

Minimal Impact ◽

Si Nanoparticle ◽

Si Nanoparticles

ABSTRACT Thermoelectric materials have been of interest for several decades due to their ability to recapture waste heat of various systems and convert it to useful electricity. One method used to improve the thermoelectric efficiency of a material is to reduce the lattice thermal conductivity (k p ) while not affecting the other properties. In order to reduce the k p of the material, this paper introduces silicon (Si) nanoparticles (NPs) in Mg2Si to manipulate phonon scattering and mean free path. A series of simulations is performed with the metal silicide thermoelectric material MgxSix. The objective of this work is two-fold: 1) to determine the optimal Si nanoparticle (NP) concentration and 2) to determine the optimal MgxSix stoichiometry for minimizing the k p of the system. It should be noted, however, that the assumed reduction in thermal conductivity is only a result of reduced phonon transport and that minimal impact is made on the transport of electrons. Interestingly, the uniform off-stoichiometry (49.55 atomic percent (a/o) Si) sample of MgxSix resulted in a reduction of k p of 84.62 %, while the Si NP sample, with matching a/o Si, resulted in a reduction of k p of 78.82 %.

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α-Bi2Sn2O7: A Potential Room Temperature n-type Oxide Thermoelectric

10.26434/chemrxiv.12420242.v1 ◽

2020 ◽

Author(s):

Warda Rahim ◽

Jonathan Skelton ◽

David Scanlon

Keyword(s):

Thermal Conductivity ◽

Low Temperature ◽

Room Temperature ◽

Lattice Thermal Conductivity ◽

Phonon Transport ◽

Consumer Electronics ◽

Low Grade ◽

Oxide Material ◽

Thermoelectric Efficiency ◽

Oxide Thermoelectrics

Interest in oxide thermoelectrics has been building due to their high thermal stability and earth-abundant constituent elements. However, the thermoelectric efficiency of flagship oxide materials remains comparatively low, and most materials only reach the maximum figure of merit, ZT, at very high temperatures, above those where the majority of low-grade industrial heat is emitted. It is important to identify thermoelectrics with high conversion efficiency closer to room temperature, particularly for lower-temperature applications such as in domestic heating, consumer electronics and electric vehicles. One of the main factors limiting the efficiency of oxide thermoelectrics is their large lattice thermal conductivities, which has inspired research into more structurally complex materials. In this study, we apply first-principles modelling to assess the low-temperature polymorph of Bi2Sn2O7 (α-Bi2Sn2O7) as a potential thermoelectric material, due to its complex crystal structure, which should suppress phonon transport, and the presence of Bi p and Sn s states in the conduction band, which should yield high electrical conductivity when donor (n) doped. Lattice-dynamics calculations using third-order perturbation theory predict an ultralow room-temperature lattice thermal conductivity of 0.4 W m-1 K-1, the lowest ever predicted for an oxide material, and suggest that nanostructuring to a grain size of 5 nm could further decrease this to 0.28 W m-1 K-1. The ultralow lattice thermal conductivity gives α-Bi2Sn2O7 a maximum ZT of 0.36 at 385 K (0.46 with nanostructuring), which is the highest low-temperature value predicted for an oxide thermoelectric. Most importantly, our analysis highlights the relationship between the structural complexity, the chemical nature of the cation, and the short phonon lifetimes, and thus provides guidelines for identifying other novel high-performance oxide thermoelectrics.

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α-Bi2Sn2O7: A Potential Room Temperature n-type Oxide Thermoelectric

10.26434/chemrxiv.12420242 ◽

2020 ◽

Author(s):

Warda Rahim ◽

Jonathan Skelton ◽

David Scanlon

Keyword(s):

Thermal Conductivity ◽

Low Temperature ◽

Room Temperature ◽

Lattice Thermal Conductivity ◽

Phonon Transport ◽

Consumer Electronics ◽

Low Grade ◽

Oxide Material ◽

Thermoelectric Efficiency ◽

Oxide Thermoelectrics

Interest in oxide thermoelectrics has been building due to their high thermal stability and earth-abundant constituent elements. However, the thermoelectric efficiency of flagship oxide materials remains comparatively low, and most materials only reach the maximum figure of merit, ZT, at very high temperatures, above those where the majority of low-grade industrial heat is emitted. It is important to identify thermoelectrics with high conversion efficiency closer to room temperature, particularly for lower-temperature applications such as in domestic heating, consumer electronics and electric vehicles. One of the main factors limiting the efficiency of oxide thermoelectrics is their large lattice thermal conductivities, which has inspired research into more structurally complex materials. In this study, we apply first-principles modelling to assess the low-temperature polymorph of Bi2Sn2O7 (α-Bi2Sn2O7) as a potential thermoelectric material, due to its complex crystal structure, which should suppress phonon transport, and the presence of Bi p and Sn s states in the conduction band, which should yield high electrical conductivity when donor (n) doped. Lattice-dynamics calculations using third-order perturbation theory predict an ultralow room-temperature lattice thermal conductivity of 0.4 W m-1 K-1, the lowest ever predicted for an oxide material, and suggest that nanostructuring to a grain size of 5 nm could further decrease this to 0.28 W m-1 K-1. The ultralow lattice thermal conductivity gives α-Bi2Sn2O7 a maximum ZT of 0.36 at 385 K (0.46 with nanostructuring), which is the highest low-temperature value predicted for an oxide thermoelectric. Most importantly, our analysis highlights the relationship between the structural complexity, the chemical nature of the cation, and the short phonon lifetimes, and thus provides guidelines for identifying other novel high-performance oxide thermoelectrics.

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Biaxial Tensile Strain-Induced Enhancement of Thermoelectric Efficiency of α-Phase Se2Te and SeTe2 Monolayers

Nanomaterials ◽

10.3390/nano12010040 ◽

2021 ◽

Vol 12 (1) ◽

pp. 40

Author(s):

Shao-Bo Chen ◽

Gang Liu ◽

Wan-Jun Yan ◽

Cui-E Hu ◽

Xiang-Rong Chen ◽

...

Keyword(s):

Thermal Conductivity ◽

Density Functional ◽

Tensile Strain ◽

Lattice Thermal Conductivity ◽

Waste Heat ◽

Electronic Conductivity ◽

Thermoelectric Efficiency ◽

Α Phase ◽

Biaxial Tensile ◽

Biaxial Tensile Strain

Thermoelectric (TE) materials can convert waste heat into electrical energy, which has attracted great interest in recent years. In this paper, the effect of biaxial-tensile strain on the electronic properties, lattice thermal conductivity, and thermoelectric performance of α-phase Se2Te and SeTe2 monolayers are calculated based on density-functional theory and the semiclassical Boltzmann theory. The calculated results show that the tensile strain reduces the bandgap because the bond length between atoms enlarges. Moreover, the tensile strain strengthens the scatting rate while it weakens the group velocity and softens the phonon model, leading to lower lattice thermal conductivity kl. Simultaneously, combined with the weakened kl, the tensile strain can also effectively modulate the electronic transport coefficients, such as the electronic conductivity, Seebeck coefficient, and electronic thermal conductivity, to greatly enhance the ZT value. In particular, the maximum n-type doping ZT under 1% and 3% strain increases up to six and five times higher than the corresponding ZT without strain for the Se2Te and SeTe2 monolayers, respectively. Our calculations indicated that the tensile strain can effectively enhance the thermoelectric efficiency of Se2Te and SeTe2 monolayers and they have great potential as TE materials.

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Эффективная масса, подвижность носителей заряда и решеточная теплопроводность в нанокомпозитных термоэлектриках на основе халькогенидов висмута и сурьмы

Физика и техника полупроводников ◽

10.21883/ftp.2021.12.51693.09 ◽

2021 ◽

Vol 55 (12) ◽

pp. 1124

Author(s):

Л.Н. Лукьянова ◽

А.А. Шабалдин ◽

А.Ю. Самунин ◽

О.А. Усов

Keyword(s):

Thermal Conductivity ◽

Material Parameter ◽

Lattice Thermal Conductivity ◽

Base Material ◽

Thermoelectric Efficiency ◽

Direct Crystallization ◽

Scattering Parameter ◽

Bismuth Chalcogenides ◽

Crystallization Method ◽

P Type

In the p-type thermoelectrics based on bismuth chalcogenides and antimony with an excess bismuth, the density of states effective mass m/m0 increases in nanocomposite and nanostructured solid solutions compared with the base material obtained by the direct crystallization method. It is shown that an increase in m/m0 is associated with an increase in the effective scattering parameter reff and amplifying the relaxation time of energy, which is typical for topological insulators. The material parameter beta, proportional to the thermoelectric efficiency of ZT, at temperatures below room increases stronger in nanostructured composition than in a nanocomposite with the inclusions of SiO2 due to the growth of m/m0 and decrease the lattice thermal conductivity κL. At high temperatures in the range of 300-500 to the greatest growth of the parameter beta in the base material associated with higher mobility.

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