Superior room-temperature power factor in GeTe systems via multiple valence band convergence to a narrow energy range

A facile energy-saving route is developed for fabricating Sb 2 Te 3 -Te nanocomposites and nanosized Te powders. The fabrication route not only avoids using organic chemicals, but also keeps the energy consumption to a minimum. The fabrication procedure involves two steps. Energetic precursors of nanosized powders of Sb and Te are produced at room temperature followed by hot pressing at 400°C under 70 MPa for 1 h. The resulting Sb 2 Te 3 -Te nanocomposite exhibits enhanced power factor. The dimensionless figure of merit zT value of the Sb 2 Te 3 -Te nanocomposite is 0.29 at 475 K.

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Near room temperature power factor of metal sulfides films

10.1063/1.4731527 ◽

2012 ◽

Cited By ~ 3

Author(s):

J. M. Clamagirand ◽

J. R. Ares ◽

I. J. Ferrer ◽

C. Sánchez

Keyword(s):

Power Factor ◽

Room Temperature ◽

Metal Sulfides

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Substitution Versus Full-Heusler Segregation in TiCoSb

Metals ◽

10.3390/met8110935 ◽

2018 ◽

Vol 8 (11) ◽

pp. 935 ◽

Cited By ~ 1

Author(s):

Maryana Asaad ◽

Jim Buckman ◽

Jan-Willem Bos

Keyword(s):

Powder Metallurgy ◽

Power Factor ◽

Thermoelectric Materials ◽

Room Temperature ◽

The Difference ◽

P Type ◽

Full Heusler ◽

Thermal Conductivities

Half-Heuslers (HHs) are promising thermoelectric materials with great compositional flexibility. Here, we extend work on the p-type doping of TiCoSb using abundant elements. Ti0.7V0.3Co0.85Fe0.15Sb0.7Sn0.3 samples with nominal 17.85 p-type electron count were investigated. Samples prepared using powder metallurgy have negative Seebeck values, S ≤ −120 µV K−1, while arc-melted compositions are compensated semiconductors with S = −45 to +30 µV K−1. The difference in thermoelectric response is caused by variations in the degree of segregation of V(Co0.6Fe0.4)2Sn full-Heusler and Sn phases, which selectively absorb V, Fe, and Sn. The segregated microstructure leads to reduced lattice thermal conductivities, κlat = 4.5−7 W m−1 K−1 near room temperature. The largest power factor, S2/ρ = 0.4 mW m−1 K−2 and ZT = 0.06, is observed for the n-type samples at 800 K. This works extends knowledge regarding suitable p-type dopants for TiCoSb.

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Quantum Interference Enhanced Thermoelectricity in Ferrocene Based Molecular Junctions

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2019.16622 ◽

2019 ◽

Vol 19 (11) ◽

pp. 7452-7455

Author(s):

Ashkan Vakilipour Takaloo ◽

Hatef Sadeghi

Keyword(s):

Seebeck Coefficient ◽

Single Molecule ◽

Power Factor ◽

Quantum Interference ◽

Room Temperature ◽

Thermoelectric Power Factor ◽

Molecular Scale ◽

Single Molecule Junctions ◽

Path Structure ◽

Single Path

Recent experimental indications of room-temperature quantum interference in the sub-nanometer single molecules suggest that such effects could be utilized to engineer thermoelectric properties of organic single molecule junctions. In this paper, we show that the thermoelectric power factor is significantly enhanced in double path ferrocene cycles compared to the single path counterpart. Due to quantum interference in the double path structure, the Seebeck coefficient is significantly enhanced while the conductance is less affected compared to single path structure. The power factor of the ferrocene cycles are 1–2 orders of magnitude higher than the best organic material reported today. This opens new avenues for future molecular scale organometallic thermoelectricity.

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Impact of the iron substitution on the thermoelectric properties of Co 1− x Fe x S 2 ( x ≤ 0.30)

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2018.0337 ◽

2019 ◽

Vol 377 (2152) ◽

pp. 20180337 ◽

Cited By ~ 1

Author(s):

Ulises Acevedo Salas ◽

Ismail Fourati ◽

Jean Juraszek ◽

Fabienne Richomme ◽

Denis Pelloquin ◽

...

Keyword(s):

Thermal Conductivity ◽

Thermal Properties ◽

Thermoelectric Properties ◽

Thermoelectric Material ◽

Power Factor ◽

Room Temperature ◽

Low Carbon ◽

Energy Materials ◽

Work Samples ◽

Lattice Part

The strong interplay between magnetism and transport can tune the thermoelectric properties in chalcogenides and oxides. In the case of ferromagnetic CoS 2 pyrite, it was previously shown that the power factor is large at room temperature, reaching 1 mW m −1 K −2 and abruptly increases for temperatures below the Curie transition ( T C ), an increase potentially due to a magnonic effect on the Seebeck ( S ) coefficient. The too large thermal conductivity approximately equal to 10.5 W m −1 K −1 at room temperature prevents this pyrite from being a good thermoelectric material. In this work, samples belonging to the Co 1− x Fe x S 2 pyrite family ( x = 0, 0.15 and 0.30) have thus been investigated in order to modify the thermal properties by the introduction of disorder on the Co site. We show here that the thermal conductivity can indeed be reduced by such a substitution, but that this substitution predominantly induces a reduction of the electronic part of the thermal conductivity and not of the lattice part. Interestingly, the magnonic contribution to S below T C disappears as x increases, while at high T , S tends to a very similar value (close to −42 µV K −1 ) for all the samples investigated. This article is part of a discussion meeting issue ‘Energy materials for a low carbon future’.

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Electronic Structure and Surface Science of delta Plutonium

MRS Proceedings ◽

10.1557/proc-802-dd2.8 ◽

2003 ◽

Vol 802 ◽

Author(s):

M. Butterfield ◽

T. Durakiewicz ◽

E. Guziewicz ◽

J. J. Joyce ◽

D. P. Moore ◽

...

Keyword(s):

Electronic Structure ◽

Laser Ablation ◽

High Resolution ◽

Valence Band ◽

Surface Science ◽

Photoelectron Spectroscopy ◽

Room Temperature ◽

Instrument Resolution ◽

Δ Phase

AbstractHigh resolution photoelectron spectroscopy (PES) studies were conducted on a δ-phase Plutonium sample cleaned by laser ablation and gas dosed with O2 and H2. The measurements were made with an instrument resolution of 60 meV and with the sample at 77 K. The PES data strongly support a model with Pu2O3 growth on the metal and then PuO2 growth on the Pu2O3 layer at this temperature. In vacuum, the PuO2 reduces to Pu2O3 at room temperature with a pressure of 6×10−11 Torr. In the case of H2 dosing the hydrogen appears to penetrate the surface and disrupt the valence band as evidenced by a drop in intensity of the peak at EF which is not accompanied by a drop in the main 5f manifold at ∼2eV.

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Annealing Effect on the Thermoelectric Properties of Bi2Te3Thin Films Prepared by Thermal Evaporation Method

Journal of Nanomaterials ◽

10.1155/2013/201017 ◽

2013 ◽

Vol 2013 ◽

pp. 1-6 ◽

Cited By ~ 8

Author(s):

Jyun-Min Lin ◽

Ying-Chung Chen ◽

Chi-Pi Lin

Keyword(s):

Thin Films ◽

Seebeck Coefficient ◽

Thermoelectric Properties ◽

Power Factor ◽

Room Temperature ◽

Annealing Temperature ◽

Thermal Evaporation ◽

Thermal Evaporation Method ◽

Si Substrates ◽

Seebeck Coefficients

Bismuth telluride-based compounds are known to be the best thermoelectric materials within room temperature region, which exhibit potential applications in cooler or power generation. In this paper, thermal evaporation processes were adopted to fabricate the n-type Bi2Te3thin films on SiO2/Si substrates. The influence of thermal annealing on the microstructures and thermoelectric properties of Bi2Te3thin films was investigated in temperature range 100–250°C. The crystalline structures and morphologies were characterized by X-ray diffraction and field emission scanning electron microscope analyses. The Seebeck coefficients, electrical conductivity, and power factor were measured at room temperature. The experimental results showed that both the Seebeck coefficient and power factor were enhanced as the annealing temperature increased. When the annealing temperature increased to 250°C for 30 min, the Seebeck coefficient and power factor of n-type Bi2Te3-based thin films were found to be about −132.02 μV/K and 6.05 μW/cm·K2, respectively.

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Quantized thermoelectric Hall effect induces giant power factor in a topological semimetal

Nature Communications ◽

10.1038/s41467-020-19850-2 ◽

2020 ◽

Vol 11 (1) ◽

Cited By ~ 1

Author(s):

Fei Han ◽

Nina Andrejevic ◽

Thanh Nguyen ◽

Vladyslav Kozii ◽

Quynh T. Nguyen ◽

...

Keyword(s):

Energy Harvesting ◽

Hall Effect ◽

Power Factor ◽

Room Temperature ◽

Waste Heat ◽

Quantum Limit ◽

Topological Materials ◽

Weyl Semimetal ◽

Topological Semimetals ◽

Electronic Entropy

AbstractThermoelectrics are promising by directly generating electricity from waste heat. However, (sub-)room-temperature thermoelectrics have been a long-standing challenge due to vanishing electronic entropy at low temperatures. Topological materials offer a new avenue for energy harvesting applications. Recent theories predicted that topological semimetals at the quantum limit can lead to a large, non-saturating thermopower and a quantized thermoelectric Hall conductivity approaching a universal value. Here, we experimentally demonstrate the non-saturating thermopower and quantized thermoelectric Hall effect in the topological Weyl semimetal (WSM) tantalum phosphide (TaP). An ultrahigh longitudinal thermopower $$S_{xx} \sim 1.1 \times 10^3 \, \mu \, {\mathrm{V}} \, {\mathrm{K}}^{ - 1}$$ S x x ~ 1.1 × 1 0 3 μ V K − 1 and giant power factor $$\sim 525 \, \mu \, {\mathrm{W}} \, {\mathrm{cm}}^{ - 1} \, {\mathrm{K}}^{ - 2}$$ ~ 525 μ W cm − 1 K − 2 are observed at ~40 K, which is largely attributed to the quantized thermoelectric Hall effect. Our work highlights the unique quantized thermoelectric Hall effect realized in a WSM toward low-temperature energy harvesting applications.

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UPS, XPS, AES STUDIES OF Te THIN FILMS DEPOSITED ON Si(100) 2×1

Surface Review and Letters ◽

10.1142/s0218625x94000734 ◽

1994 ◽

Vol 01 (04) ◽

pp. 589-592 ◽

Cited By ~ 1

Author(s):

S. DI NARDO ◽

L. LOZZI ◽

M. PASSACANTANDO ◽

P. PICOZZI ◽

S. SANTUCCI

Keyword(s):

Thin Films ◽

Film Thickness ◽

Electronic Properties ◽

Valence Band ◽

Room Temperature ◽

Surface States ◽

Growth Mode ◽

Characteristic Behavior ◽

Complete Study ◽

Nominal Coverage

This work represents the first complete study of the interaction between Te and Si in very thin films of tellurium grown at room temperature on Si(100) 2×1 surfaces. In particular, the electronic properties have been investigated by UPS and XPS measurements and information on growth of tellurium on silicon have been obtained by AES measurements. Our results indicate that the interaction between tellurium and silicon is weak, taking the characteristic behavior of simple metals. Increasing the film thickness, the growth mode is one layer, completed with about 2 Å of Te nominal coverage, plus islanding, until the thickness reaches the value of about 10 Å, followed by coalescence of islands. When tellurium has completed a layer, the valence band surface states of silicon are quenched.

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Electrical Properties of Heavily Be-doped GaAs grown by Molecular Beam Epitaxy

MRS Proceedings ◽

10.1557/proc-163-121 ◽

1989 ◽

Vol 163 ◽

Cited By ~ 4

Author(s):

H. Shibata ◽

Y. Makita ◽

A. Yamada ◽

N. Ohnishi ◽

M. Mori ◽

...

Keyword(s):

Electrical Properties ◽

Molecular Beam Epitaxy ◽

Low Temperature ◽

Carrier Concentration ◽

Valence Band ◽

Temperature Region ◽

Room Temperature ◽

Molecular Beam ◽

Impurity Band ◽

Carrier Scattering

AbstractElectrical properties of heavily Be-doped GaAs grown by molecular beam epitaxy were investigated systematically in a wide range of Be-concentration from 1× 1014 up to 2× 1020 cm-3 by using yan der Pauw technique. Probable carrier scattering mechanisms observed in this work are discussed by taking into account the radiative mechanisms of several new photoluminescence emissions previously observed in the band-edge-emission region of the samples. All samples were checked their electrical properties first at room-temperature. Five selected samples out of them were measured from 10° K up to room-temperature. Samples having the carrier concentration from 1014 to 1018 cm3 presented typical semiconductor-like conduction with finite carrier excitation energy. For samples having carrier concentration 7× 1016 cm -3, the conduction mechanism at high temperature region above 30β K was dominated by holes thermally excited into valence band. At low temperature region below 30° K . it was dominated by holes hopping from neutral to ionized acceptors with the assistance of phonons. Hole mobilities of samples having the carrier concentration from 1017 to 1018 cm-3 showed an anomalous behavior in the low temperature region, which suggests the presence of a new type of carrier scattering mechanism. A radiative center denoted by lg-gl observed in this concentration region will be a candidate scattering center to explain these electrical behaviors. Samples having the carrier concentration larger than 1019 cm-3 demonstrated typically metallic electric conduction not owing to thermally excited carriers, which means that an impurity band is formed but merged with valence band. The density of state of this combined valence band mixed with impurity band can be supposed to reflect carrier concentration dependence of the PL emission bands observed in this region, i.e. [g-g]α , [g-g]β and [g-g]γ .

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