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.

Structure and thermoelectric properties of the n-type clathrate Ba8Cu5.1Ge40.2Sn0.7

2015 ◽  
Vol 3 (37) ◽  
pp. 19100-19106 ◽  
Author(s):  
Jingtao Xu ◽  
Jiazhen Wu ◽  
Hezhu Shao ◽  
Satoshi Heguri ◽  
Yoichi Tanabe ◽  
...  
Keyword(s):  
Single Crystals ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Type I ◽  
Thermoelectric Figure Of Merit ◽  
Flux Method ◽  
Thermoelectric Figure ◽  
Space Group ◽  
Maximum Value ◽  
Study Type

We study type I clathrate Ba8Cu5.1Ge40.2Sn0.7 single crystals (space group Pm3̄n, no. 223, a = 10.7151(3)) grown using a Sn flux method, and the thermoelectric figure of merit ZT of single crystals reaches a maximum value of 0.6 at 773 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.

scholarly journals The impact of charge transfer and structural disorder on the thermoelectric properties of cobalt intercalated TiS2

2016 ◽  
Vol 4 (9) ◽  
pp. 1871-1880 ◽  
Author(s):  
Gabin Guélou ◽  
Paz Vaqueiro ◽  
Jesús Prado-Gonjal ◽  
Tristan Barbier ◽  
Sylvie Hébert ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Charge Transfer ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Structural Disorder ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Figure ◽  
Low Levels ◽  
The Impact

The thermoelectric figure of merit of TiS2 is increased by 25% through the intercalation of low levels of cobalt due to an increased electrical conductivity, arising from charge transfer, and a reduced thermal conductivity resulting from disorder.

Melt Spinning Preparation of Bismuth Telluride and Partially Alloying with IV-VI Compounds for Thermoelectric Application

2007 ◽  
Vol 1044 ◽  
Author(s):  
Harald Boettner ◽  
Dirk Ebling ◽  
Alexandre Jacquot ◽  
Uta Kühn ◽  
Jürgen Schmidt ◽  
...  
Keyword(s):  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Melt Spinning ◽  
Thermoelectric Figure Of Merit ◽  
Bulk Materials ◽  
Thermoelectric Figure ◽  
Post Annealing ◽  
Melt Spin ◽  
Melt Spinning Technique ◽  
Thermoelectric Application

AbstractThe melt spinning technique (MST) combined with post annealing processes is evaluated for the development of thermoelectric nanocomposites. The evaluated ones are based on two components almost immiscible in solid state but with crystallographic correlation. One is taken from the V-VI-components system and the other one from the IV-VI-components system. This concept was applied to p-(Bi0,2Sb0,8)2Te3 and to p-[(Bi0,2Sb0,8)2Te3]1-xPbTex composites. MST samples of all types were characterised for some structural and thermoelectric properties. All V-VI materials are clearly textured after MST and show no deterioration concerning the thermoelectric properties even after subsequent annealing processes. Structural analysis of p-[(Bi0,2Sb0,8)2Te3]1-xPbTex composites gave significant hints for oriented precipitates of a IV-VI-rich phase incorporated into the V-VI-rich matrix. The thermoelectric figure of merit of the evaluated composites could be enhanced by suitable annealing procedures of both the quenched bulk materials and the melt spin material.

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.

Highly electrical and thermoelectric properties of a PEDOT:PSS thin-film via direct dilution–filtration

RSC Advances ◽  
2015 ◽  
Vol 5 (75) ◽  
pp. 60708-60712 ◽  
Author(s):  
Jinhua Xiong ◽  
Fengxing Jiang ◽  
Weiqiang Zhou ◽  
Congcong Liu ◽  
Jingkun Xu
Keyword(s):  
Thin Film ◽  
Electrical Conductivity ◽  
Organic Solvents ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Thermoelectric Figure Of Merit ◽  
High Electrical Conductivity ◽  
Thermoelectric Figure

A flexible PEDOT:PSS thin-film achieves a high electrical conductivity (1500 S cm−1) and a high thermoelectric figure of merit (ZT ∼ 0.1) by a rapid direct dilution–filtration with common organic solvents.

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.

Influence of multi-sintering on the thermoelectric properties of Bi2Sr2Co2Oy ceramics

2019 ◽  
Vol 34 (02) ◽  
pp. 2050019 ◽  
Author(s):  
Y. Zhang ◽  
M. M. Fan ◽  
C. C. Ruan ◽  
Y. W. Zhang ◽  
X.-J. Li ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Phonon Scattering ◽  
Sintered Sample ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Figure ◽  
The Third ◽  
Ceramic Samples ◽  
Optimum Formula

[Formula: see text] ceramic samples have a structure similar to phonon glass electronic crystals, and their thermoelectric properties can be effectively adjusted through repeated grinding and sintering. The results show that multi-sintering can make their grain refined and increase their grain boundary, which will effectively increase density and phonon scattering. Finally, multi-sintering can reduce the resistivity and thermal conductivity, thus obviously improve thermoelectric figure of merit [Formula: see text] of [Formula: see text]. The optimum [Formula: see text] value of 0.26 is achieved at 923 K by the third sintered sample.

Effects of Ce filling fraction and Fe content on the thermoelectric properties of Co-rich CeyFexCo4−xSb12

2001 ◽  
Vol 16 (3) ◽  
pp. 837-843 ◽  
Author(s):  
Xinfeng Tang ◽  
Lidong Chen ◽  
Takashi Goto ◽  
Toshio Hirai
Keyword(s):  
Thermal Conductivity ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Single Phase ◽  
Lattice Thermal Conductivity ◽  
Hole Concentration ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Figure ◽  
Filling Fraction ◽  
Fe Content

Single-phase filled skutterudite compounds, CeyFexCo4−xSb12 (x = 0 to 3.0, y = 0 to 0.74), were synthesized by a melting method. The effects of Fe content and Ce filling fraction on the thermoelectric properties of CeyFexCo4−xSb12 were investigated. The lattice thermal conductivity of Ce-saturated CeyFexCo4−xSb12, y being at the maximum corresponding to x, decreased with increasing Fe content (x) and reached its minimum at about x = 1.5. When x was 1.5, lattice thermal conductivity decreased with increasing Ce filling fraction till y = 0.3 and then began to increase after reaching the minimum at y = 0.3. Hole concentration and electrical conductivity of Cey Fe1.5Co2.5Sb12 decreased with increasing Ce filling fraction. The Seebeck coefficient increased with increasing Ce filling fraction. The greatest dimensionless thermoelectric figure of merit T value of 1.1 was obtained at 750 K for the composition of Ce0.28Fe1.52Co2.48Sb12.

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.

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