Thermoelectric Properties of Nb-Doped SrTiO3 / TiO2 Multiphase Composite

2009 ◽  
Vol 1166 ◽  
Author(s):  
Kiyoshi Fuda ◽  
Kenji Murakami ◽  
Tomoyoshi Shoji ◽  
Shigeaki Sugiyama
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Figure Of Merit ◽  
Fine Particles ◽  
Phase Region ◽  
The Other ◽  
Two Phase ◽  
Typical Size ◽  
Dimensionless Figure Of Merit ◽  
Multiphase Composite

AbstractIn this study, we fabricated and examined a series of multiphase type composites constructed of Nb-doped SrTiO3 / TiO2 fine particles. The composition of the composites and the sintering temperatures were selected in a two-phase region where a perovskite SrTiO3 and a rutile TiO2 phases coexist. The composites obtained here were found to commonly have a mosaic type texture constructed of TiO2 and SrTiO3 fine particles with a typical size of about 500 nm. In some samples we also found additive phases such as Sr6Ti7Nb9O42. The thermal conductivity values measured for the most samples with different contents are ranged between 2 and 5 Wm-1K-1. The values are apparently lower than the value for single crystal SrTiO3 samples presented in literature. A sample with rather low relative density of about 80% showed a quite low thermal conductivity, about 1 Wm-1K-1. Taking account the other TE data, e.g. Seebeck coefficient and electrical conductivity, we calculated dimensionless figure of merit, ZT, to be at maximum 0.24 at 600°C.

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

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).

Thermoelectrical properties of α phase and γ phase NaxCo2O4 ceramics prepared by spark plasma sintering method

2013 ◽  
Vol 1490 ◽  
pp. 57-62 ◽  
Author(s):  
Natsuko Mikami ◽  
Keishi Nishio ◽  
Koya Arai ◽  
Tatsuya Sakamoto ◽  
Masahiro Minowa ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Spark Plasma Sintering ◽  
Figure Of Merit ◽  
Dimensionless Figure Of Merit ◽  
Α Phase ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Sintering Method ◽  
Acid Compound

ABSTRACTThe thermoelectrical properties of α and γ phases of NaxCo2O4 having different amounts of Na were evaluated. The γ NaxCo2O4 samples were synthesized by thermal decomposition in a metal-citric acid compound, and the α NaxCo2O4 samples were synthesized by self-flux processing. Dense bulk ceramics were fabricated using spark plasma sintering (SPS), and the sintered samples were of high density and highly oriented. The thermoelectrical properties showed that γ NaxCo2O4 had higher electrical conductivity and lower thermal conductivity compared with α NaxCo2O4 and that α NaxCo2O4 had a larger Seebeck coefficient. These results show that γ NaxCo2O4 has a larger power factor and dimensionless figure of merit, ZT, than α NaxCo2O4.

Preparation and Thermoelectric Properties of Bi-Doped Mg2Si Nanocomposites

2009 ◽  
Vol 66 ◽  
pp. 17-20 ◽  
Author(s):  
Mei Jun Yang ◽  
Wei Jun Luo ◽  
Qiang Shen ◽  
Hong Yi Jiang ◽  
Lian Meng Zhang
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Seebeck Coefficient ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Dimensionless Figure Of Merit ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Heavy Doping ◽  
Nanocomposite Structures

Nanocomposites and heavy doping both are regarded as effective way to improve materials’ thermoelectric properties. 0.7at% Bi-doped Mg2Si nanocomposites were prepared by spark plasma sintering. Results of thermoelectric properties tests show that the doping of Bi atom effectively improves the electrical conductivity of Mg2Si，and the nanocomposite structures are helpful to reduce thermal conductivity and increase Seebeck coefficient, hence improving the thermoelectric performance. A maximum dimensionless figure of merit of 0.8 is obtained for the Bi-doped Mg2Si nanocomposite with 50 wt % nanopowder inclusions at 823K, about 63% higher than that of Bi-doped Mg2Si sample without nanopowder inclusions and 119% higher than that of microsized Mg2Si sample without Bi-doped, respectively.

Raising the Thermoelectric Performance of Fe3CoSb12 Skutterudites via Nd Filling and In-Situ Nanostructuring

2016 ◽  
Vol 16 (4) ◽  
pp. 3841-3847 ◽  
Author(s):  
Lijie Guo ◽  
Zhengwei Cai ◽  
Xiaolong Xu ◽  
Kunling Peng ◽  
Guiwen Wang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Thermoelectric Performance ◽  
Large Reduction ◽  
Dimensionless Figure Of Merit ◽  
Plasma Sintering ◽  
Spark Plasma

p-type skutterudites NdxFe3CoSb12 with x equaling 0.8, 0.85, 0.9, 0.95, 1.0 have been synthesized by solid state reaction followed by spark plasma sintering. The influence of Nd filling on electrical and thermal transport properties has been investigated in the Nd-filled skutterudite compounds in the temperature range from room temperature to 800 K. It was found that the Seebeck coefficient is drastically enhanced via filling Nd in p-Type skutterudites as well as the corresponding power factor although electrical conductivity is reduced. In addition, a large reduction in thermal conductivity is achieved by Nd fillers through rattling effect along with the In-Situ nanostructured precipitate through scattering phonons with much wider frequency. These concomitant effects result in an enhanced thermoelectric performance with the dimensionless figure of merit ZT. These observations demonstrate an exciting scientific opportunity to raise the figure-of-merit of p-type skutterudites.

Investigating the Effects of Sodium Chloride Particles on Thermoelectric Properties of Bismuth Telluride

2017 ◽  
Author(s):  
T. Alexander ◽  
M. Rahman ◽  
R. Asmatulu
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Sodium Chloride ◽  
Seebeck Coefficient ◽  
Bismuth Telluride ◽  
Figure Of Merit ◽  
Hot Water ◽  
Dimensionless Figure Of Merit ◽  
Before And After ◽  
Baseline Sample

Cylindrical pellets of near stoichiometric bismuth telluride (Bi2Te3) powder with NaCl particles were made using a cold pressing and pressureless sintering technique. The sodium chloride was leached out from the samples in hot water, resulting in porous samples with varying levels of porosity. The electrical conductivity, Seebeck coefficient, and thermal conductivity were measured at room temperature using a testing apparatus designed and built by the researcher, both before and after the leaching of sodium chloride. From this data, the figure of merit was calculated. Samples of pure bismuth telluride (0% NaCl) served as the baseline samples for comparison. Both the presence of NaCl and pores were efficient at increasing the dimensionless figure of merit. Porous samples initially containing 20% NaCl had a 37.55% higher figure of merit compared to baseline samples, and an 89.07% increase in the figure of merit was seen from the solid samples with NaCl inclusions at a concentration of 30% by volume. The electrical conductivity was negatively affected by both inclusions and porosity, but significant increases in Seebeck coefficient, and reduced thermal conductivity were significantly enough for an overall increase in dimensionless figure of merit. The figure of merit for the baseline sample was approximately 0.18, and the highest values observed for the NaCl inclusion and porous samples were 0.34 and 0.25 respectively. These values are far less than that of what is considered a state of the art thermoelectric material, but the materials and methods used were simple, inexpensive, and scalable, showing great potential for applicability for use with optimized thermoelectric materials in hopes of further increasing their figure of merit.

Thermoelectric Properties of M2Mo6Se6 (M=TI, In)

1997 ◽  
Vol 478 ◽  
Author(s):  
D. T. Verebelyi ◽  
J. E. Payne ◽  
G. X. Tessema ◽  
E. Mengistu
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Figure Of Merit ◽  
Linear Chain ◽  
One Dimensional ◽  
Dimensionless Figure Of Merit ◽  
The Family ◽  
Good Potential ◽  
Chain Compounds ◽  
Related Compounds

AbstractWe have measured the thermal conductivity of TI2Mo6Se6, a quasi-one dimensional conductor which belongs to the family of M2Mo6X6 linear chain compounds. Using these results and our measurements of the Seebeck coefficient and the electrical conductivity we estimate the dimensionless figure of merit to be of the order of 0.08. This result suggest that this compound and other related compounds are good potential TE.

FEM Analysis on Thermoelectric Properties of Metal/TiO2–x Composites with Random Distribution of Metal Powder

2013 ◽  
Vol 750 ◽  
pp. 130-133
Author(s):  
Katsuhiro Sagara ◽  
Yun Lu ◽  
Dao Cheng Luan
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Seebeck Coefficient ◽  
Thermoelectric Properties ◽  
Power Factor ◽  
Figure Of Merit ◽  
Random Distribution ◽  
The Other ◽  
Dimensionless Figure Of Merit ◽  
Wide Range

Analysis model of finite element method with a random distribution for thermoelectric composites was built. Thermoelectric properties including electrical resistivity, Seebeck coefficient and thermal conductivity of M/TiO2–x (M = Cu, Ni, 304 stainless steel (304SS)) thermoelectric composites were investigated by the proposed model. Cu/TiO2–x composite showed a large decrease in electrical resistivity while 304SS/TiO2–x composite thermal conductivity was slightly increased. Calculated dimensionless figure-of-merit, ZT of Ni/TiO2–x composite was higher than those of TiO2–x and the other composites in a wide range of metal volume fractions because Ni has large absolute values of Seebeck coefficient, power factor and dimensionless figure-of-merit compared to the other two metals. It was found that power factor and dimensionless figure-of-merit of thermoelectric composites depended on the balance among electrical resistivity, thermal conductivity and Seebeck coefficient. The results revealed that it is important for M/TiO2–x composites to choose suitable addition metal with high power factor and dimensionless figure-of-merit.

MeV Si Ions Bombardment Effects on SiO2/SiO2-ZrNiSn Nano-layered Thermoelectric Generator

2008 ◽  
Vol 1102 ◽  
Author(s):  
S. Budak ◽  
S. Guner ◽  
C. Muntele ◽  
D. ILA
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Thermal Properties ◽  
Seebeck Coefficient ◽  
Figure Of Merit ◽  
Thermoelectric Generator ◽  
Rutherford Backscattering Spectrometry ◽  
Absolute Temperature ◽  
Dimensionless Figure Of Merit ◽  
Before And After

AbstractWe have deposited 50 nano-layers of 710 nm of SiO2/SiO2+ZrNiSn with a periodic structure consisting of alternating layers where each layer is about 14 nm thick. The purpose of this research is to generate nanolayers of nanostructures of ZrNiSn with SiO2 as host and as buffer layer using a combination of co-deposition and MeV ion bombardment taking advantage of the energy deposited in the MeV ions track to nucleate nanostructures. The performance of the thermoelectric materials and devices is shown by a dimensionless figure of merit, ZT = S2σT/ĸ, where S is the Seebeck coefficient, σ is the electrical conductivity, T is the absolute temperature and ĸ is the thermal conductivity. ZT can be increased by increasing S, increasing σ, or decreasing ĸ. The electrical and thermal properties of the layered structures were studied before and after bombardment by 5 MeV Si ions at seven different fluences ranging from 1014 to 1015 ions/cm2 in order to form nanostructures in layers of SiO2 containing few percent of ZrNiSn. Rutherford Backscattering Spectrometry (RBS) was used to monitor elemental analysis of the film.

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

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
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).

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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