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Special Issue "Low-Dimensional Anisotropic Thermoelectrics"

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Materials for Energy Applications".

Deadline for manuscript submissions: closed (31 January 2015)

Special Issue Editors

Guest Editor
Prof. Dr. Kunihito Koumoto

Graduate School of Engineering Department of Applied Chemistry Chemical Engineering and Biotechnology Nagoya University Nagoya 464-8603 Japan
Website | E-Mail
Guest Editor
Dr. Chunlei Wan

Graduate School of Engineering Department of Applied Chemistry Chemical Engineering and Biotechnology Nagoya University Nagoya 464-8603 Japan
Website | E-Mail

Special Issue Information

Dear Colleagues,

Thermoelectric material research has recently flourished with the emergence of novel concepts of band engineering, nanostructuring and discoveries of various novel materials. Particularly, materials with low dimensional structure provide unprecedented opportunities to decouple phonon and electron transport properties and thereby high thermoelectric performance. These low dimensional anisotropic materials could have a very high electrical conductivity along one specific crystallographic direction, but have phonons strongly scattered by the dissimilar interfaces or anharmonic atomic bonding. Furthermore, quantum confinement of phonon and electron in the low-dimensional structure could lead to yet undiscovered, emergent electronic or thermal phenomena and possibly high thermoelectricity. In this special issue, we would like to focus on the recent development of low dimensional anisotropic thermoelectrics, including both experimental and theoretical studies of electron and phonon transport in two-dimensional nanosheets, materials with natural superlattice structures, anisotropic layered materials or one-dimensional materials. Novel synthesis strategies of atomic-level layered materials are particularly appreciated.

It is my pleasure to invite you to submit a manuscript for this special issue. Full papers, communications, and reviews are all welcome.

Kunihito Koumoto
Chunlei Wan
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Materials is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1500 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

 

Keywords

  • thermoelectric materials
  • anisotropic
  • natural superlattice
  • interface phonon scattering
  • anharmonicity
  • two-dimensional nanosheet
  • intercalation
  • inorganic/organic hybrid

Published Papers (9 papers)

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Research

Jump to: Review

Open AccessArticle Rapid Synthesis and Formation Mechanism of Core-Shell-Structured La-Doped SrTiO3 with a Nb-Doped Shell
Materials 2015, 8(7), 3992-4003; doi:10.3390/ma8073992
Received: 11 March 2015 / Revised: 14 June 2015 / Accepted: 24 June 2015 / Published: 2 July 2015
PDF Full-text (2295 KB) | HTML Full-text | XML Full-text
Abstract
To provide a convenient and practical synthesis process for metal ion doping on the surface of nanoparticles in an assembled nanostructure, core-shell-structured La-doped SrTiO3 nanocubes with a Nb-doped surface layer were synthesized via a rapid synthesis combining a rapid sol-precipitation and hydrothermal
[...] Read more.
To provide a convenient and practical synthesis process for metal ion doping on the surface of nanoparticles in an assembled nanostructure, core-shell-structured La-doped SrTiO3 nanocubes with a Nb-doped surface layer were synthesized via a rapid synthesis combining a rapid sol-precipitation and hydrothermal process. The La-doped SrTiO3 nanocubes were formed at room temperature by a rapid dissolution of NaOH pellets during the rapid sol-precipitation process, and the Nb-doped surface (shell) along with Nb-rich edges formed on the core nanocubes via the hydrothermal process. The formation mechanism of the core-shell-structured nanocubes and their shape evolution as a function of the Nb doping level were investigated. The synthesized core-shell-structured nanocubes could be arranged face-to-face on a SiO2/Si substrate by a slow evaporation process, and this nanostructured 10 μm thick thin film showed a smooth surface. Full article
(This article belongs to the Special Issue Low-Dimensional Anisotropic Thermoelectrics)
Open AccessArticle Synthesis and Thermoelectric Properties in the 2D Ti1 xNbxS3 Trichalcogenides
Materials 2015, 8(5), 2514-2522; doi:10.3390/ma8052514
Received: 25 March 2015 / Revised: 10 April 2015 / Accepted: 22 April 2015 / Published: 11 May 2015
Cited by 5 | PDF Full-text (1077 KB) | HTML Full-text | XML Full-text
Abstract
A solid solution of Ti1 − xNbxS3 composition (x = 0, 0.05, 0.07, 0.10) was synthesized by solid-liquid-vapor reaction followed by spark plasma sintering. The obtained compounds crystallize in the monoclinic ZrSe3 structure type. For the
[...] Read more.
A solid solution of Ti1 − xNbxS3 composition (x = 0, 0.05, 0.07, 0.10) was synthesized by solid-liquid-vapor reaction followed by spark plasma sintering. The obtained compounds crystallize in the monoclinic ZrSe3 structure type. For the x = 0.07 sample, a mixture of both A and B variants of the MX3 structure is evidenced by transmission electron microscopy. This result contrasts with those of pristine TiS3, prepared within the same conditions, which crystallizes as a large majority of A variant. Thermoelectric properties were investigated in the temperature range 323 to 523 K. A decrease in the electrical resistivity and absolute value of the Seebeck coefficient is observed when increasing x due to electron doping. The lattice component of the thermal conductivity is effectively reduced by the Nb for Ti substitution through a mass fluctuation effect and/or a disorder effect created by the mixture of both A and B variants. Due to the low carrier concentration and the semiconductor character of the doped compounds, the too low power factor values leads to ZT values that remain smaller by a factor of 50 than those of the TiS2 layered compound. Full article
(This article belongs to the Special Issue Low-Dimensional Anisotropic Thermoelectrics)
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Open AccessCommunication Enhanced Thermoelectric Performance of Bi2O2Se with Ag Addition
Materials 2015, 8(4), 1568-1576; doi:10.3390/ma8041568
Received: 9 February 2015 / Revised: 5 March 2015 / Accepted: 6 March 2015 / Published: 1 April 2015
Cited by 4 | PDF Full-text (1148 KB) | HTML Full-text | XML Full-text
Abstract
Polycrystalline Bi2O2Se/Ag nanocomposites were synthesized by spark plasma sintering process. Their thermoelectric properties were evaluated from 300 to 673 K. With the addition of silver, the conductive second phase Ag2Se and Ag can be observed, which results
[...] Read more.
Polycrystalline Bi2O2Se/Ag nanocomposites were synthesized by spark plasma sintering process. Their thermoelectric properties were evaluated from 300 to 673 K. With the addition of silver, the conductive second phase Ag2Se and Ag can be observed, which results in a significant enhancement of electrical conductivity. The maximum conductivity is 691.8 S cm−1 for Bi2O2Se/20 vol.% Ag, which increased nearly 500 higher times than the pure Bi2O2Se bulk. ZT value can be enhanced greatly, ~0.07, for Bi2O2Se/5 vol.% Ag at 673 K, which is two times larger than the pure sample. Full article
(This article belongs to the Special Issue Low-Dimensional Anisotropic Thermoelectrics)
Open AccessArticle Structure and Transport Properties of the BiCuSeO-BiCuSO Solid Solution
Materials 2015, 8(3), 1043-1058; doi:10.3390/ma8031043
Received: 20 January 2015 / Revised: 24 February 2015 / Accepted: 5 March 2015 / Published: 12 March 2015
Cited by 6 | PDF Full-text (625 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
In this paper, we report on the crystal structure and the electrical and thermal transport properties of the BiCuSe1−xSxO series. From the evolution of the structural parameters with the substitution rate, we can confidently conclude that a complete solid
[...] Read more.
In this paper, we report on the crystal structure and the electrical and thermal transport properties of the BiCuSe1−xSxO series. From the evolution of the structural parameters with the substitution rate, we can confidently conclude that a complete solid solution exists between the BiCuSeO and BiCuSO end members, without any miscibility gap. However, the decrease of the stability of the materials when increasing the sulfur fraction, with a simultaneous volatilization, makes it difficult to obtain S-rich samples in a single phase. The band gap of the materials linearly increases between 0.8 eV for BiCuSeO and 1.1 eV in BiCuSO, and the covalent character of the Cu-Ch (Ch = chalcogen element, namely S or Se here) bond slightly decreases when increasing the sulfur fraction. The thermal conductivity of the end members is nearly the same, but a significant decrease is observed for the samples belonging to the solid solution, which can be explained by point defect scattering due to atomic mass and radii fluctuations between Se and S. When increasing the sulfur fraction, the electrical resistivity of the samples strongly increases, which could be linked to an evolution of the energy of formation of copper vacancies, which act as acceptor dopants in these materials. Full article
(This article belongs to the Special Issue Low-Dimensional Anisotropic Thermoelectrics)
Open AccessArticle Fe-Doping Effect on Thermoelectric Properties of p-Type Bi0.48Sb1.52Te3
Materials 2015, 8(3), 959-965; doi:10.3390/ma8030959
Received: 9 January 2015 / Revised: 17 February 2015 / Accepted: 26 February 2015 / Published: 5 March 2015
Cited by 4 | PDF Full-text (761 KB) | HTML Full-text | XML Full-text
Abstract
The substitutional doping approach has been shown to be an effective strategy to improve ZT of Bi2Te3-based thermoelectric raw materials. We herein report the Fe-doping effects on electronic and thermal transport properties of polycrystalline bulks of p-type Bi
[...] Read more.
The substitutional doping approach has been shown to be an effective strategy to improve ZT of Bi2Te3-based thermoelectric raw materials. We herein report the Fe-doping effects on electronic and thermal transport properties of polycrystalline bulks of p-type Bi0.48Sb1.52Te3. After a small amount of Fe-doping on Bi/Sb-sites, the power factor could be enhanced due to the optimization of carrier concentration. Additionally, lattice thermal conductivity was reduced by the intensified point-defect phonon scattering originating from the mass difference between the host atoms (Bi/Sb) and dopants (Fe). An enhanced ZT of 1.09 at 300 K was obtained in 1.0 at% Fe-doped Bi0.48Sb1.52Te3 by these synergetic effects. Full article
(This article belongs to the Special Issue Low-Dimensional Anisotropic Thermoelectrics)
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Review

Jump to: Research

Open AccessReview Misfit Layer Compounds and Ferecrystals: Model Systems for Thermoelectric Nanocomposites
Materials 2015, 8(4), 2000-2029; doi:10.3390/ma8042000
Received: 6 February 2015 / Revised: 3 April 2015 / Accepted: 7 April 2015 / Published: 22 April 2015
Cited by 13 | PDF Full-text (4023 KB) | HTML Full-text | XML Full-text
Abstract
A basic summary of thermoelectric principles is presented in a historical context, following the evolution of the field from initial discovery to modern day high-zT materials. A specific focus is placed on nanocomposite materials as a means to solve the challenges presented by
[...] Read more.
A basic summary of thermoelectric principles is presented in a historical context, following the evolution of the field from initial discovery to modern day high-zT materials. A specific focus is placed on nanocomposite materials as a means to solve the challenges presented by the contradictory material requirements necessary for efficient thermal energy harvest. Misfit layer compounds are highlighted as an example of a highly ordered anisotropic nanocomposite system. Their layered structure provides the opportunity to use multiple constituents for improved thermoelectric performance, through both enhanced phonon scattering at interfaces and through electronic interactions between the constituents. Recently, a class of metastable, turbostratically-disordered misfit layer compounds has been synthesized using a kinetically controlled approach with low reaction temperatures. The kinetically stabilized structures can be prepared with a variety of constituent ratios and layering schemes, providing an avenue to systematically understand structure-function relationships not possible in the thermodynamic compounds. We summarize the work that has been done to date on these materials. The observed turbostratic disorder has been shown to result in extremely low cross plane thermal conductivity and in plane thermal conductivities that are also very small, suggesting the structural motif could be attractive as thermoelectric materials if the power factor could be improved. The first 10 compounds in the [(PbSe)1+δ]m(TiSe2)n family (m, n ≤ 3) are reported as a case study. As n increases, the magnitude of the Seebeck coefficient is significantly increased without a simultaneous decrease in the in-plane electrical conductivity, resulting in an improved thermoelectric power factor. Full article
(This article belongs to the Special Issue Low-Dimensional Anisotropic Thermoelectrics)
Open AccessReview Chemical Potential Tuning and Enhancement of Thermoelectric Properties in Indium Selenides
Materials 2015, 8(3), 1283-1324; doi:10.3390/ma8031283
Received: 25 January 2015 / Revised: 10 March 2015 / Accepted: 11 March 2015 / Published: 20 March 2015
Cited by 4 | PDF Full-text (5448 KB) | HTML Full-text | XML Full-text
Abstract
Researchers have long been searching for the materials to enhance thermoelectric performance in terms of nano scale approach in order to realize phonon-glass-electron-crystal and quantum confinement effects. Peierls distortion can be a pathway to enhance thermoelectric figure-of-merit ZT by employing natural nano-wire-like electronic
[...] Read more.
Researchers have long been searching for the materials to enhance thermoelectric performance in terms of nano scale approach in order to realize phonon-glass-electron-crystal and quantum confinement effects. Peierls distortion can be a pathway to enhance thermoelectric figure-of-merit ZT by employing natural nano-wire-like electronic and thermal transport. The phonon-softening known as Kohn anomaly, and Peierls lattice distortion decrease phonon energy and increase phonon scattering, respectively, and, as a result, they lower thermal conductivity. The quasi-one-dimensional electrical transport from anisotropic band structure ensures high Seebeck coefficient in Indium Selenide. The routes for high ZT materials development of In4Se3δ are discussed from quasi-one-dimensional property and electronic band structure calculation to materials synthesis, crystal growth, and their thermoelectric properties investigations. The thermoelectric properties of In4Se3δ can be enhanced by electron doping, as suggested from the Boltzmann transport calculation. Regarding the enhancement of chemical potential, the chlorine doped In4Se3δCl0.03 compound exhibits high ZT over a wide temperature range and shows state-of-the-art thermoelectric performance of ZT = 1.53 at 450 °C as an n-type material. It was proven that multiple elements doping can enhance chemical potential further. Here, we discuss the recent progress on the enhancement of thermoelectric properties in Indium Selenides by increasing chemical potential. Full article
(This article belongs to the Special Issue Low-Dimensional Anisotropic Thermoelectrics)
Open AccessReview Hierarchical Architecturing for Layered Thermoelectric Sulfides and Chalcogenides
Materials 2015, 8(3), 1124-1149; doi:10.3390/ma8031124
Received: 4 February 2015 / Revised: 25 February 2015 / Accepted: 26 February 2015 / Published: 16 March 2015
Cited by 19 | PDF Full-text (3337 KB) | HTML Full-text | XML Full-text | Correction
Abstract
Sulfides are promising candidates for environment-friendly and cost-effective thermoelectric materials. In this article, we review the recent progress in all-length-scale hierarchical architecturing for sulfides and chalcogenides, highlighting the key strategies used to enhance their thermoelectric performance. We primarily focus on TiS2-based
[...] Read more.
Sulfides are promising candidates for environment-friendly and cost-effective thermoelectric materials. In this article, we review the recent progress in all-length-scale hierarchical architecturing for sulfides and chalcogenides, highlighting the key strategies used to enhance their thermoelectric performance. We primarily focus on TiS2-based layered sulfides, misfit layered sulfides, homologous chalcogenides, accordion-like layered Sn chalcogenides, and thermoelectric minerals. CS2 sulfurization is an appropriate method for preparing sulfide thermoelectric materials. At the atomic scale, the intercalation of guest atoms/layers into host crystal layers, crystal-structural evolution enabled by the homologous series, and low-energy atomic vibration effectively scatter phonons, resulting in a reduced lattice thermal conductivity. At the nanoscale, stacking faults further reduce the lattice thermal conductivity. At the microscale, the highly oriented microtexture allows high carrier mobility in the in-plane direction, leading to a high thermoelectric power factor. Full article
(This article belongs to the Special Issue Low-Dimensional Anisotropic Thermoelectrics)
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Open AccessReview Recent Progress on PEDOT-Based Thermoelectric Materials
Materials 2015, 8(2), 732-750; doi:10.3390/ma8020732
Received: 6 January 2015 / Revised: 23 January 2015 / Accepted: 9 February 2015 / Published: 16 February 2015
Cited by 46 | PDF Full-text (2314 KB) | HTML Full-text | XML Full-text
Abstract
The thermoelectric properties of poly(3,4-ethylenedioxythiophene) (PEDOT)-based materials have attracted attention recently because of their remarkable electrical conductivity, power factor, and figure of merit. In this review, we summarize recent efforts toward improving the thermoelectric properties of PEDOT-based materials. We also discuss thermoelectric measurement
[...] Read more.
The thermoelectric properties of poly(3,4-ethylenedioxythiophene) (PEDOT)-based materials have attracted attention recently because of their remarkable electrical conductivity, power factor, and figure of merit. In this review, we summarize recent efforts toward improving the thermoelectric properties of PEDOT-based materials. We also discuss thermoelectric measurement techniques and several unsolved problems with the PEDOT system such as the effect of water absorption from the air and the anisotropic thermoelectric properties. In the last part, we describe our work on improving the power output of thermoelectric modules by using PEDOT, and we outline the potential applications of polymer thermoelectric generators. Full article
(This article belongs to the Special Issue Low-Dimensional Anisotropic Thermoelectrics)

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