scholarly journals Enhanced Thermoelectric Properties of WS2/Single-Walled Carbon Nanohorn Nanocomposites

Crystals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 140 ◽  
Author(s):  
Ji Hoon Kim ◽  
Seunggun Yu ◽  
Sang Won Lee ◽  
Seung-Yong Lee ◽  
Keun Soo Kim ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Seebeck Coefficient ◽  
Thermoelectric Properties ◽  
High Frequency ◽  
Figure Of Merit ◽  
Thermoelectric Efficiency ◽  
Thermoelectric Figure ◽  
Carbon Nanohorns ◽  
Single Walled Carbon ◽  
High Frequency Induction

Recently, two-dimensional tungsten disulfide (WS2) has attracted attention as a next generation thermoelectric material due to a favorable Seebeck coefficient. However, its thermoelectric efficiency still needs to be improved due to the intrinsically low electrical conductivity of WS2. In the present study, thermoelectric properties of WS2 hybridized with highly conductive single-walled carbon nanohorns (SWCNHs) were investigated. The WS2/SWCNH nanocomposites were fabricated by annealing the mixture of WS2 and SWCNHs using a high-frequency induction heated sintering (HFIHS) system. By adding SWCNHs to WS2, the nanocomposites exhibited increased electrical conductivity and a slightly decreased Seebeck coefficient with the content of SWCNHs. Hence, the maximum power factor of 128.41 μW/mK2 was achieved for WS2/SWCNHs with 0.1 wt.% SWCNHs at 780 K, resulting in a significantly improved thermoelectric figure of merit (zT) value of 0.027 compared to that of pristine WS2 with zT 0.017.

Improving the Thermoelectric Properties of the Material and Increasing the Efficiency of Conversion Processes

2021 ◽  
Vol 23 (5) ◽  
pp. 243-246
Author(s):  
D.G. Mustafaeva ◽  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Mean Free Path ◽  
Charge Carriers ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Efficiency ◽  
Thermoelectric Figure ◽  
Phonon Component

The area of practical application of thermoelectric materials depends on the value of the thermoelectric figure of merit. The use of semiconductor materials makes it possible to realize the conditions under which the ratio of their parameters ensures the achievement of high values of thermoelectric figure of merit. The achievement of the maximum thermoelectric figure of merit causes an increase in the efficiency of conversion processes due to the improvement of the thermoelectric properties of the material. The position of the maximum value of the thermoelectric figure of merit is predetermined by the scattering parameters and the ratio of the mobilities and effective masses of charge carriers. The nature of the change in electrical conductivity is determined by the behavior of the concentration of charge carriers. Thermal conductivity, like electrical conductivity, is proportional to the concentration of electrons and the mean free path. An increase in thermoelectric efficiency is achieved by optimizing thermoelectric parameters by doping and improving the properties of com¬pounds, which leads to an optimization of the concentration of charge carriers, a change in the density of states, and a decrease in the phonon component of thermal conductivity. The improvement of the thermoelectric properties of the material and the increase in the efficiency of the conversion processes are provided at a certain concentration of charge carriers, which corresponds to the optimal value.

Thermoelectric Properties of Ni Doped P-Type BiCuSeO Oxyselenides

2014 ◽  
Vol 602-603 ◽  
pp. 906-909 ◽  
Author(s):  
Yao Chun Liu ◽  
Jun Fu Liu ◽  
Bo Ping Zhang ◽  
Yuan Hua Lin
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Seebeck Coefficient ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Layer Structure ◽  
Thermoelectric Figure Of Merit ◽  
Ni Doping ◽  
Thermoelectric Figure ◽  
P Type

We report on the effect of Ni doping on the thermoelectric properties of p-type BiCuSeO oxyselenide, with layer structure composed of conductive (Cu2Se2)2-layers alternately stacked with insulating (Bi2O2)2+layers along c axis. After doping with Ni, enhanced electrical conductivity coupled with a moderate Seebeck coefficient leads to a power factor of ~231 μwm-1K-2at 873 K. Coupled to low thermal conductivity, ZT at 873 K is increased from 0.35 for pristine BiCuSeO to 0.39 for Bi0.95Ni0.05CuSeO. However, the efficiency of Ni doping in the insulating (Bi2O2)2+layer is low, and this doping only leads to a limited increase of the hole carriers concentration. Therefore Ni doped BiCuSeO has relatively low electrical conductivity which makes its thermoelectric figure of merit much lower than that of Ca, Sr, Ba and Pb doped BiCuSeO.

The Influence of Silicon Dopant and Processing on Thermoelectric Properties of B4C Ceramics

1998 ◽  
Vol 545 ◽  
Author(s):  
Ke-Feng Cai ◽  
Ce-Wen Nan ◽  
Xin-Min Min
Keyword(s):  
Electrical Conductivity ◽  
Seebeck Coefficient ◽  
Thermoelectric Properties ◽  
Hot Pressing ◽  
Figure Of Merit ◽  
Room Temperature ◽  
A Value ◽  
Si Doped

AbstractB4C ceramics doped with various content of Si (0 to 2.03 at%) are prepared via hot pressing. The composition and microstructure of the ceramics are characterized by means of XRD and EPMA. Their electrical conductivity and Seebeck coefficient of the samples are measured from room temperature up to 1500K. The electrical conductivity increases with temperature, and more rapidly after 1300K; the Seebeck coefficient of the ceramics also increases with temperature and rises to a value of about 320μVK−1. The value of the figure of merit of Si-doped B4C rises to about 4 × 10−4K−1 at 1500K.

scholarly journals Термоэлектрические свойства нанокомпозитного Bi-=SUB=-0.45-=/SUB=-Sb-=SUB=-1.55-=/SUB=-Te-=SUB=-2.985-=/SUB=- с микрочастицами SiO-=SUB=-2-=/SUB=-

2019 ◽  
Vol 53 (6) ◽  
pp. 751
Author(s):  
А.А. Шабалдин ◽  
П.П. Константинов ◽  
Д.А. Курдюков ◽  
Л.Н. Лукьянова ◽  
А.Ю. Самунин ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Solid Solution ◽  
Electrical Conductivity ◽  
Wide Temperature Range ◽  
Figure Of Merit ◽  
Nanostructured Material ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Efficiency ◽  
Thermoelectric Figure ◽  
P Type

AbstractNanocomposite thermoelectrics based on Bi_0.45Sb_1.55Te_2.985 solid solution of p -type conductivity are fabricated by the hot pressing of nanopowders of this solid solution with the addition of SiO_2 microparticles. Investigations of the thermoelectric properties show that the thermoelectric power of the nanocomposites increases in a wide temperature range of 80–420 K, while the thermal conductivity considerably decreases at 80–320 K, which, despite a decrease in the electrical conductivity, leads to an increase in the thermoelectric efficiency in the nanostructured material without the SiO_2 addition by almost 50% (at 300 K). When adding SiO_2, the efficiency decreases. The initial thermoelectric fabricated without nanostructuring, in which the maximal thermoelectric figure of merit ZT = 1 at 390 K, is most efficient at temperatures above 350 K.

Thermoelectric Properties of n-type (Bi2Se3)x(Bi2Te3)1-x Crystals Prepared by Zone Melting

2008 ◽  
Vol 368-372 ◽  
pp. 547-549
Author(s):  
Jun Jiang ◽  
Ya Li Li ◽  
Gao Jie Xu ◽  
Ping Cui ◽  
Li Dong Chen
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Seebeck Coefficient ◽  
Carrier Concentration ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Zone Melting ◽  
Chemical Compositions ◽  
Melting Method ◽  
Temperature Range

In the present study, n-type (Bi2Se3)x(Bi2Te3)1-x crystals with various chemical compositions were fabricated by the zone melting method. Thermoelectric properties, including Seebeck coefficient (α), electrical conductivity (σ) and thermal conductivity (κ), were measured in the temperature range of 300-500 K. The influence of the variations of Bi2Te3 and Bi2Se3 content on thermoelectric properties was studied. The increase of Bi2Se3 content (x) caused an increase in carrier concentration and thus an increase of σ and a decrease of α. The maximum figure of merit (ZT = α2σT/κ) of 0.87 was obtained at about 325 K for the composition of 93%Bi2Te3-7%Bi2Se3 with doping TeI4.

Synthesis and Thermoelectric Properties of Co4-XFeXSb12-YSnY Skutterudites

2011 ◽  
Vol 695 ◽  
pp. 65-68 ◽  
Author(s):  
Kwan Ho Park ◽  
Il Ho Kim
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Seebeck Coefficient ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Phonon Scattering ◽  
Charge Compensation ◽  
Fe Doping ◽  
Sn Doping ◽  
Double Doping

Co4-xFexSb12-ySny skutterudites were synthesized by mechanical alloying and hot pressing, and thermoelectric properties were examined. The carrier concentration increased by doping and thereby the electrical conductivity increased compared with intrinsic CoSb3. Every specimen had a positive Seebeck coefficient. Fe doping caused a decrease in the Seebeck coefficient but it could be enhanced by Fe/Sn double doping possibly due to charge compensation. The thermal conductivity was desirably very low and this originated from ionized impurity-phonon scattering. Thermoelectric properties were improved remarkably by Fe/Sn doping, and a maximum figure of merit, ZT = 0.5 was obtained at 723 K in the Co3FeSb11.2Sn0.8 specimen.

Thermoelectric Properties of YbBiPt and YBiPt Thin Films

2008 ◽  
Vol 1100 ◽  
Author(s):  
Sadik Guner ◽  
Satilmis Budak ◽  
Claudiu I Muntele ◽  
Daryush Ila
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Seebeck Coefficient ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Rutherford Backscattering Spectrometry ◽  
Conductivity Measurement ◽  
Electronic Energy ◽  
Before And After

AbstractMonolayer thin films of YbBiPt and YBiPt have been produced with 560 nm and 394 nm thick respectively in house and their thermoelectric properties were measured before and after MeV ion bombardment. The energy of the ions were selected such that the bombarding Si ions stop in the silicon substrate and deposit only electronic energy by ionization in the deposited thin film. The bombardment by 5.0 MeV Si ions at various fluences changed the homogeneity as well as reducing the internal stress in the films thus affecting the thermal, electrical and Seebeck coefficient of thin films. The stoichiometry of the thin films was determined using Rutherford Backscattering Spectrometry, the thickness has been measured using interferometry and the electrical conductivity was measured using Van der Pauw method. Thermal conductivity of the thin films was measured using an in-house built 3ω thermal conductivity measurement system. Using the measured Seebeck coefficient, thermal conductivity and electrical conductivity we calculated the figure of merit (ZT). We will report our findings of change in the measured figure of merit as a function of bombardment fluence.

Enhancement of thermoelectric figure of merit by incorporation of large single crystals in Ca3Co4O9 bulk materials

2003 ◽  
Vol 18 (7) ◽  
pp. 1646-1651 ◽  
Author(s):  
Ryoji Funahashi ◽  
Saori Urata ◽  
Toyohide Sano ◽  
Masaaki Kitawaki
Keyword(s):  
Electrical Conductivity ◽  
Composite Material ◽  
Single Crystals ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Thermoelectric Figure Of Merit ◽  
Bulk Materials ◽  
Flux Method ◽  
Thermoelectric Figure ◽  
Grain Alignment

Having recently succeeded in synthesizing large single crystals of (Ca2CoO3)CoO2 (Co-349) with superior thermoelectric properties using a modified flux method, we have prepared a composite material of Co-349 powder and single crystals and examined its thermoelectric properties. The electrical conductivity σ of this composite, which contained 20 wt.% single crystals, was higher than that of a sample without the single crystals. While the achievable effect has yet to be fully realized, improved grain alignment and the effect of current bypassing grain boundaries through the large single crystals in the composite are thought to cause the increasing σ, which consequently results in an enhanced thermoelectric figure of merit of about 0.56 at 973 K in air.

Effect of Nanocavities on the Thermoelectric Properties of Polycrystalline Silicon

2011 ◽  
Vol 1329 ◽  
Author(s):  
Ekaterina Selezneva ◽  
Andrea Arcari ◽  
Gilles Pernot ◽  
Elisabetta Romano ◽  
Gianfranco Cerofolini ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Seebeck Coefficient ◽  
Thermoelectric Properties ◽  
Polycrystalline Silicon ◽  
Figure Of Merit ◽  
Annealing Temperature ◽  
Silicon Films ◽  
Negative Effect ◽  
Polycrystalline Silicon Films

ABSTRACTNanostructuring has opened new ways to increase the thermoelectric performance of a host of materials, mainly by decreasing their thermal conductivity κ while preserving the Seebeck coefficient S and electrical conductivity σ. The thermoelectric properties of degenerated polycrystalline silicon films with nanocavities (NCs) have been studied as a function of annealing temperature upon isochronous annealings in argon carried out every 50°C in the range 500 – 1000°C which were used to modify the shape of the NCs. We found that presence of the NCs had no negative effect on the electronic properties of the system. The measured values of S and σ were close to those previously reported for the blank polycrystalline silicon films with the same doping level. The thermal conductivity was also found to be close to the value measured on the blank sample, about half of the reported value in polycrystals. This led to a power factor of 15.2 mWm-1K-2 and a figure of merit of 0.18 at 300 K.

Thermoelectric Properties of a Wide–Gap Chalcopyrite Compound AgInSe2

2012 ◽  
Vol 519 ◽  
pp. 188-192 ◽  
Author(s):  
P.Z. Ying ◽  
H. Zhou ◽  
Y.L. Gao ◽  
Y.Y. Li ◽  
Y.P. Li ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Chemical Compositions ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Figure ◽  
Remarkable Improvement ◽  
Wide Gap ◽  
Chalcopyrite Compound

Here we report the thermoelectric properties of a wide–gap chalcopyrite compound AgInSe2, and observed the remarkable improvement in electrical conductivity σ, due to the bandgap (Eg = 1.12 eV) reduction compared to In2Se3. The improvement in σ is directly responsible for the enhancement of thermoelectric figure of merit ZT, though the thermal conductivity is much higher at 500 ~ 724 K. The maximum ZT value is 0.34 at 724 K, increasing by a factor of 4, indicating that this chalcopyrite compound is of a potential thermoelectric candidate if further optimizations of chemical compositions and structure are made.

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