Electrical and thermal transport behaviours of high-entropy perovskite thermoelectric oxides

AbstractOxide-based ceramics could be promising thermoelectric materials because of their thermal and chemical stability at high temperature. However, their mediocre electrical conductivity or high thermal conductivity is still a challenge for the use in commercial devices. Here, we report significantly suppressed thermal conductivity in SrTiO3-based thermoelectric ceramics via high-entropy strategy for the first time, and optimized electrical conductivity by defect engineering. In high-entropy (Ca0.2Sr0.2Ba0.2Pb0.2La0.2)TiO3 bulks, the minimum thermal conductivity can be 1.17 W/(m·K) at 923 K, which should be ascribed to the large lattice distortion and the huge mass fluctuation effect. The power factor can reach about 295 μW/(m·K2) by inducing oxygen vacancies. Finally, the ZT value of 0.2 can be realized at 873 K in this bulk sample. This approach proposed a new concept of high entropy into thermoelectric oxides, which could be generalized for designing high-performance thermoelectric oxides with low thermal conductivity.

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Investigation of Thermoelectric Materials: Substitution effect of Bi on the Ag1-xPb18MTe20 (M = Sb, Bi) (x = 0, 0.14, 0.3)

MRS Proceedings ◽

10.1557/proc-1044-u03-14 ◽

2007 ◽

Vol 1044 ◽

Author(s):

Mi-kyung Han ◽

Huijun Kong ◽

Ctirad Uher ◽

Mercouri G Kanatzidis

Keyword(s):

Thermal Conductivity ◽

Electrical Conductivity ◽

Seebeck Coefficient ◽

Thermoelectric Materials ◽

Figure Of Merit ◽

Lattice Thermal Conductivity ◽

Substitution Effect ◽

Dimensionless Figure Of Merit ◽

The Matrix ◽

Mass Fluctuation

AbstractWe performed comparative investigations of the Ag1-xPb18MTe20 (M = Bi, Sb) (x = 0, 0.14, 0.3) system to better understand the roles of Sb and Bi on the thermoelectric properties. In both systems, the electrical conductivity nearly keeps the same values, while the Seebeck coefficient decreases dramatically in going from Sb to Bi. Compared to the lattice thermal conductivity of PbTe, that of AgPb18BiTe20 is substantially reduced. The lattice thermal conductivity of the Bi analog, however, is higher than that of AgPb18SbTe20 and this is attributed largely to the decrease in the degree of mass fluctuation between the nanostructures and the matrix (for the Bi analog). As a result the dimensionless figure of merit ZT of Ag1-xPb18MTe20 (M = Bi) is found to be smaller than that of Ag1-xPb18MTe20 (M = Sb).

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Efficient interlayer charge release for high-performance layered thermoelectrics

National Science Review ◽

10.1093/nsr/nwaa085 ◽

2020 ◽

Cited By ~ 3

Author(s):

Hao Zhu ◽

Zhou Li ◽

Chenxi Zhao ◽

Xingxing Li ◽

Jinlong Yang ◽

...

Keyword(s):

Thermal Conductivity ◽

Electrical Conductivity ◽

Seebeck Coefficient ◽

Carrier Concentration ◽

High Performance ◽

Lattice Thermal Conductivity ◽

Transport Barrier ◽

High Seebeck Coefficient ◽

Valence Bands ◽

Increase Carrier Concentration

Abstract Many layered superlattice materials intrinsically possess large Seebeck coefficient and low lattice thermal conductivity, but poor electrical conductivity because of the interlayer transport barrier for charges, which has become a stumbling block for achieving high thermoelectric performance. Herein, taking BiCuSeO superlattice as an example, it is demonstrated that efficient interlayer charge release can increase carrier concentration, thereby activating multiple Fermi pockets through Bi/Cu dual vacancies and Pb codoping. Experimental results reveal that the extrinsic charges, which are introduced by Pb and initially trapped in the charge-reservoir [Bi2O2]2+ sublayers, are effectively released into [Cu2Se2]2− sublayers via the channels bridged by Bi/Cu dual vacancies. This efficient interlayer charge release endows dual-vacancy- and Pb-codoped BiCuSeO with increased carrier concentration and electrical conductivity. Moreover, with increasing carrier concentration, the Fermi level is pushed down, activating multiple converged valence bands, which helps to maintain a relatively high Seebeck coefficient and yield an enhanced power factor. As a result, a high ZT value of ∼1.4 is achieved at 823 K in codoped Bi0.90Pb0.06Cu0.96SeO, which is superior to that of pristine BiCuSeO and solely doped samples. The present findings provide prospective insights into the exploration of high-performance thermoelectric materials and the underlying transport physics.

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Thermoelectric properties of Zn– and Ce–alloyed In2O3 and the effect of SiO2 nanoparticle additives

Nanotechnology ◽

10.1088/1361-6528/ac4307 ◽

2021 ◽

Author(s):

Cheng-Lun Hsin ◽

Jen-Che Hsiao ◽

You-Ming Chen ◽

Sheng-Wei Lee

Keyword(s):

Thermal Conductivity ◽

Electrical Conductivity ◽

Porous Structure ◽

Energy Conversion ◽

Thermoelectric Module ◽

Cost Effective ◽

Sio2 Nanoparticle ◽

Thermoelectric Oxides ◽

The Matrix ◽

Nanoparticle Additives

Abstract Thermoelectric materials are considered promising candidates for thermal energy conversion. This study presents the fabrication of Zn– and Ce–alloyed In2O3 with a porous structure. The electrical conductivity was improved by the alloying effect and an ultra–low thermal conductivity was observed owing to the porous structure, which concomitantly provide a distinct enhancement of ZT. However, SiO2 nanoparticle additives react with the matrix to form a third-phase impurity, which weakens the electrical conductivity and increases the thermal conductivity. A thermoelectric module was constructed for the purpose of thermal heat energy conversion. Our experimental results proved that both an enhancement in electrical conductivity and a suppression in thermal conductivity could be achieved through nano–engineering. This approach presents a feasible route to synthesize porous thermoelectric oxides, and provides insight into the effect of additives; moreover, this approach is a cost-effective method for the fabrication of thermoelectric oxides without traditional hot-pressing and spark–plasma–sintering processes.

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Enhanced Thermoelectric Characteristics of Ag2Se Nanoparticle Thin Films by Embedding Silicon Nanowires

Energies ◽

10.3390/en13123072 ◽

2020 ◽

Vol 13 (12) ◽

pp. 3072

Author(s):

Seunggen Yang ◽

Kyoungah Cho ◽

Sangsig Kim

Keyword(s):

Thin Film ◽

Thermal Conductivity ◽

Electrical Conductivity ◽

Thermoelectric Material ◽

Silicon Nanowires ◽

High Performance ◽

Conductivity Measurement ◽

Thermoelectric Generators ◽

Seebeck Coefficients ◽

Thermal Conductivities

A solution-processable Ag2Se nanoparticle thin film (NPTF) is a prospective thermoelectric material for plastic-based thermoelectric generators, but its low electrical conductivity hinders the fabrication of high performance plastic-based thermoelectric generators. In this study, we design Ag2Se NPTFs embedded with silicon nanowires (SiNWs) to improve their thermoelectric characteristics. The Seebeck coefficients are −233 and −240 µV/K, respectively, for a Ag2Se NPTF alone and a Ag2Se NPTF embedded with SiNWs. For the Ag2Se NPTF embedded with SiNWs, the electrical conductivity is improved from 0.15 to 18.5 S/m with the embedment of SiNWs. The thermal conductivities are determined by a lateral thermal conductivity measurement for nanomaterials and the thermal conductivities are 0.62 and 0.84 W/(m·K) for a Ag2Se NPTF alone and a Ag2Se NPTF embedded with SiNWs, respectively. Due to the significant increase in the electrical conductivity and the insignificant increase in its thermal conductivity, the output power of the Ag2Se NPTF embedded with SiNWs is 120 times greater than that of the Ag2Se NPTF alone. Our results demonstrate that the Ag2Se NPTF embedded with SiNWs is a prospective thermoelectric material for high performance plastic-based thermoelectric generators.

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Microwave Irradiation to Produce High Performance Thermoelectric Material Based on Al Doped ZnO Nanostructures

Crystals ◽

10.3390/cryst10070610 ◽

2020 ◽

Vol 10 (7) ◽

pp. 610

Author(s):

Neazar Baghdadi ◽

Numan Salah ◽

Ahmed Alshahrie ◽

Kunihito Koumoto

Keyword(s):

Thermal Conductivity ◽

Electrical Conductivity ◽

Microwave Irradiation ◽

High Performance ◽

Figure Of Merit ◽

Room Temperature ◽

Zno Nanostructures ◽

Al Doping ◽

Doped Zno ◽

Te Material

Microwave irradiation is found to be effective to provide highly crystalline nanostructured materials. In this work, this technique has been used to produce highly improved thermoelectric (TE) material based on aluminum (Al) doped zinc oxide (ZnO) nanostructures (NSs). The effect of Al dopant at the concentration range 0.5–3 mol % on the structural and TE properties has been investigated in more details. The optimum concentration of Al for better TE performance is found to be 2 mol %, which could significantly increase the electrical conductivity and reduce the thermal conductivity of ZnO NSs and thus enhance the TE performance. This concentration showed almost metallic conductivity behavior for ZnO NSs at low temperatures, e.g., below 500 K. The electrical conductivity reached 400 S/m at room temperature, which is around 200 times greater than the value recorded for the pure ZnO NSs. Remarkably, the measured room temperature thermal conductivity of the microwave synthesized ZnO NSs was very low, which is around 4 W/m·K. This value was further reduced to 0.5 W/m·K by increasing the Al doping to 3 mol %. The figure of merit recorded 0.028 at 675 K, which is 15 times higher than that of the pure ZnO NSs. The output power of a single leg module made of 2 mol % Al doped ZnO NSs was 3.7 µW at 485 K, which is higher by 8 times than that of the pure sample. These results demonstrated the advantage of the microwave irradiation rout as a superior synthetic technique for producing and doping promising TE nanomaterials like ZnO NSs.

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Smart design of free-standing ultrathin Co–Co(OH)2 composite nanoflakes on 3D nickel foam for high-performance electrochemical capacitors

Chemical Communications ◽

10.1039/c4cc07499h ◽

2015 ◽

Vol 51 (9) ◽

pp. 1689-1692 ◽

Cited By ~ 30

Author(s):

Zheyin Yu ◽

Zhenxiang Cheng ◽

Siti Rohana Majid ◽

Zhixin Tai ◽

Xiaolin Wang ◽

...

Keyword(s):

Mechanical Properties ◽

Electrical Conductivity ◽

High Performance ◽

Nickel Foam ◽

Electrochemical Capacitors ◽

Free Standing ◽

First Time

Free-standing Co–Co(OH)2 composite nanoflakes with excellent electrical conductivity and mechanical properties were applied in electrochemical capacitors for the first time.

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A High-Performance Solution-Processable Hybrid Thermoelectric Material

ASME 2012 Third International Conference on Micro/Nanoscale Heat and Mass Transfer ◽

10.1115/mnhmt2012-75002 ◽

2012 ◽

Cited By ~ 1

Author(s):

Shannon K. Yee ◽

Nelson Coates ◽

Jeffrey J. Urban ◽

Arun Majumdar ◽

Rachel A. Segalman

Keyword(s):

Thermal Conductivity ◽

Electrical Conductivity ◽

Transport Properties ◽

Conducting Polymer ◽

Thermoelectric Material ◽

Electrical Transport ◽

High Performance ◽

Full Potential ◽

Solution Processable ◽

Electrical Generation

Thermoelectrics have the potential to become an alternative power source for distributed electrical generation as they could provide co-generation anywhere thermal gradients exist. More recent material and manufacturing advances have further suggested that thermoelectrics could independently generate primary power [1]. However, due to cost, manufacturability, abundance, and material performance, the full potential of thermoelectrics has yet to be realized. In the last decade, thermoelectric material improvements have largely been realized by diminishing thermal conductivities via nanostructuring without sacrificing performance in electrical transport [2]. An alternative approach is to decouple and optimize the electrical conductivity and thermopower using the unique properties of organic-inorganic interfaces [3]. One method to do this could leverage the electrical properties of a conducting polymer in combination with the thermoelectric proprieties of an inorganic semiconductor in such a way that the interaction between these materials breaks mixture theory. Furthermore, it is expected that the thermal conductivity of this hybrid material would be low due to the inherent vibration mode mismatch between polymers and inorganics. Previously, we have developed a method for producing a solution-processable thermoelectric material suitable for thin film applications using a hybrid polymer-inorganic systems consisting of crystalline tellurium nanowires coated in a thin layer of a conducting polymer (i.e., PEDOT:PSS) [4]. The interfacial properties could be realized in bulk and films demonstrate enhanced transport properties beyond those of either component. More recently, we have been able to significantly improve the thermoelectric properties of these materials by morphological and chemical modifications. Here, we present our methodology and experimental transport properties of this new material where the thermal conductivity, electrical conductivity, and thermopower predictably vary as a function of composition, size, and the structural conformation caused by the solvent. The mechanism for these improvements is currently under investigation, but experimental results suggest that transport is dominated by interfacial phenomena. Furthermore, experiments suggest that both the electrical conductivity and thermopower can be independently increased without appreciably increasing the thermal conductivity. These improvements, in concert with the solution processable nature of this material, make it ideal for new thermoelectric applications.

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Electronic and Thermal Transport Properties of Complex Structured Cu-Bi-Se Thermoelectric Compound with Low Lattice Thermal Conductivity

Journal of Nanomaterials ◽

10.1155/2013/502150 ◽

2013 ◽

Vol 2013 ◽

pp. 1-7 ◽

Cited By ~ 3

Author(s):

Jae-Yeol Hwang ◽

Hyeona Mun ◽

Jung Young Cho ◽

Sang Sun Yang ◽

Kyu Hyoung Lee ◽

...

Keyword(s):

Thermal Conductivity ◽

Electrical Conductivity ◽

Thermal Properties ◽

Figure Of Merit ◽

Lattice Thermal Conductivity ◽

Phonon Scattering ◽

Dimensionless Figure Of Merit ◽

Impurity Doping ◽

Electron Carriers ◽

Mass Fluctuation

Monoclinic Cux+yBi5−ySe8structure has multiple disorders, such as randomly distributed substitutional and interstitial disorders by Cu as well as asymmetrical disorders by Se. Herein, we report the correlation of electronic and thermal properties with the structural complexities of Cux+yBi5−ySe8. It is found that the interstitial Cu site plays an important role not only to increase the electrical conductivity due to the generation of electron carriers but also to reduce the thermal conductivity mainly due to the phonon scattering by mass fluctuation. With impurity doping at the interstitial Cu site, an extremely low lattice thermal conductivity of 0.32 W·m−1·K−1was achieved at 560 K. These synergetic effects result in the enhanced dimensionless figure of merit (ZT).

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Effect of Heat Treatment on the Properties of Wood-Derived Biocarbon Structures

Materials ◽

10.3390/ma11091588 ◽

2018 ◽

Vol 11 (9) ◽

pp. 1588 ◽

Cited By ~ 3

Author(s):

Min Yu ◽

Theo Saunders ◽

Taicao Su ◽

Francesco Gucci ◽

Michael Reece

Keyword(s):

Thermal Conductivity ◽

Heat Treatment ◽

Electrical Conductivity ◽

Compressive Strength ◽

Thermal Properties ◽

High Temperature ◽

Hierarchical Structures ◽

Catalytic Graphitization ◽

Duration Time ◽

First Time

Wood-derived porous graphitic biocarbons with hierarchical structures were obtained by high-temperature (2200–2400 °C) non-catalytic graphitization, and their mechanical, electrical and thermal properties are reported for the first time. Compared to amorphous biocarbon produced at 1000 °C, the graphitized biocarbon-2200 °C and biocarbon-2400 °C exhibited increased compressive strength by ~38% (~36 MPa), increased electrical conductivity by ~8 fold (~29 S/cm), and increased thermal conductivity by ~5 fold (~9.5 W/(m·K) at 25 °C). The increase of duration time at 2200 °C contributed to increased thermal conductivity by ~12%, while the increase of temperature from 2200 to 2400 °C did not change their thermal conductivity, indicating that 2200 °C is sufficient for non-catalytic graphitization of wood-derived biocarbon.

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Superionic Lithium Intercalation through 2 nm x 2 nm Columns in the Crystallographic Shear Phase Nb18W8O69

10.26434/chemrxiv.11231153.v1 ◽

2019 ◽

Author(s):

Kent Griffith ◽

Clare Grey

Keyword(s):

High Performance ◽

Rate Capability ◽

Block Size ◽

Lithium Intercalation ◽

Resonance Spectroscopy ◽

Complex Metal Oxides ◽

Battery Electrode ◽

Crystallographic Shear ◽

Battery Material ◽

First Time

Nb18W8O69 (9Nb2O5×8WO3) is the tungsten-rich end-member of the Wadsley–Roth crystallographic shear (cs) structures within the Nb2O5–WO3 series. It has the largest block size of any known, stable Wadsley–Roth phase, comprising 5 ´ 5 units of corner-shared MO6 octahedra between the shear planes, giving rise to 2 nm ´ 2 nm blocks. Rapid lithium intercalation is observed in this new candidate battery material and 7Li pulsed field gradient nuclear magnetic resonance spectroscopy – measured in a battery electrode for the first time at room temperature – reveals superionic lithium conductivity. In addition to its promising rate capability, Nb18W8O69 adds a piece to the larger picture of our understanding of high-performance Wadsley–Roth complex metal oxides.

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