共查询到20条相似文献,搜索用时 31 毫秒
1.
C. Stiewe T. Dasgupta L. Böttcher B. Pedersen E. Müller B. Iversen 《Journal of Electronic Materials》2010,39(9):1975-1980
Because of its complex structure, Zn4Sb3 exhibits relatively low thermal conductivity. This, in combination with large values of the Seebeck coefficient and moderate
to high electrical conductivity, makes the material especially interesting for thermoelectric application in temperatures
up to 400°C. The phase purity and thermal stability of Zn4Sb3 are major issues for its thermoelectric performance and are strongly dependent on the synthesis method, atmosphere, density,
and grain size. Therefore, Zn4Sb3 was prepared by both zone melting and quenching in this study, and pressed samples from crushed powders of three different
grain sizes were compared. The effect of thermal cycling was studied, along with repeated structural analysis and Seebeck
mapping. It was found that zone melting leads to improved thermal stability regarding decomposition via Zn loss, which finally
may result in the formation of ZnSb. Larger grain size seems to reduce the degradation, because of lower concentration of
grain boundaries, thus hindering diffusion inside the material. 相似文献
2.
A mechanical alloying (MA) process to transform elemental powders into solid Pb0.5Sn0.5Te with thermoelectric functionality comparable to melt-alloyed material is described. The room-temperature doping level and
mobility as well as temperature-dependent electrical conductivity, Seebeck coefficient, and thermal conductivity are reported.
Estimated values of lattice thermal conductivity (0.7 W m−1 K−1) are lower than some reports of functional melt-alloyed PbSnTe-based material, providing evidence that MA can engender the
combination of properties resulting in highly functional thermoelectric material. Though doping level and Sn composition have
not been optimized, this material exhibits a ZT value >0.5 at 550 K. 相似文献
3.
Ruixue Chen Qingsen Meng Wenhao Fan Liqi Wang Zhong Wang 《Journal of Electronic Materials》2011,40(5):765-768
Field-activated pressure-assisted sintering (FAPAS) was applied to sinter Bi1.2Sb4.8Te9 thermoelectric materials under different conditions, including no-current sintering (NCS), low-density current sintering
(LCS), and high-density current sintering (HCS). The effect of the current density on the final thermoelectric performance
of the products was investigated. Applying a higher-density electric current and shorter dwell time can improve the thermoelectric
performance of the sample by increasing its electric conductivity and decreasing its thermal conductivity. The maximum figure
of merit ZT values of the NCS, LCS, and HCS samples were 0.46, 0.48, and 0.57, respectively. Therefore, applying a high-density electric
current in the sintering process may be an effective way to obtain Bi1.2Sb4.8Te9 thermoelectric material with high ZT value. 相似文献
4.
G. D. Tang Z. H. Wang X. N. Xu Y. He L. Qiu Y. W. Du 《Journal of Electronic Materials》2011,40(5):611-614
The thermoelectric properties of indium (In) and lutetium (Lu) double-filled skutterudites In
x
Lu
y
Co4Sb12 prepared by high-pressure synthesis were investigated in detail from 4 K to 365 K. Our results indicate that In and Lu double
filling can remarkably reduce the thermal conductivity, and substantially improve the thermoelectric performance. A thermoelectric
figure of merit of ZT = 0.27 for In0.13Lu0.05Co4.02Sb12 was achieved at 365 K, being larger by one order of magnitude than that for CoSb3. It is thought that the large difference in resonance frequencies of the In and Lu elements broadens the range of normal
phonon scattering in the multifilled skutterudites, helping to achieve an even lower lattice thermal conductivity. This investigation
suggests that an effective way to improve the thermoelectric performance of skutterudite materials is to use In and Lu double
filling. 相似文献
5.
Catherine A. Cox Shawna R. Brown G. Jeffrey Snyder Susan M. Kauzlarich 《Journal of Electronic Materials》2010,39(9):1373-1375
Complex Zintl phases possess low thermal conductivity and can be easily doped to modify the transport properties. Therefore,
these phases have the potential to be good thermoelectric materials by simply controlling carrier concentration. Yb14MnSb11 is a Zintl phase that has shown promise as a p-type thermoelectric material for high-temperature power generation. A Sn-flux synthetic route was used to make the new phase,
Yb13CaMnSb11. The high-temperature thermoelectric properties were measured on polycrystalline hot-pressed pellets and compared with Yb14MnSb11. Substitution of the lighter isovalent Ca for Yb should reduce the lattice thermal conductivity by mass disorder scattering,
and a noticeable reduction is seen in thermal diffusivity measurements at high temperature. There may also be a carrier concentration
effect by employing the more electropositive Ca. 相似文献
6.
n-Type nanoporous Bi2Te3-based thermoelectric materials with different porosity ratios have been prepared by spark plasma sintering (SPS). The microstructure
and phase morphology have been analyzed by x-ray diffraction (XRD) and field-emission scanning electron microscopy (FESEM),
and the thermoelectric properties of the SPS samples have been measured. Experimental results show that the nanoporous structures
lying in the sheet layers and among the plate grains of the Bi2Te3 bulk material can lead to an increase in the Seebeck coefficient and a decrease in the thermal conductivity, thus leading
to an enhanced figure of merit. 相似文献
7.
Tong Zhou Bertrand Lenoir Candolfi Christophe Anne Dauscher Philippe Gall Patrick Gougeon Michel Potel Emmanuel Guilmeau 《Journal of Electronic Materials》2011,40(5):508-512
Thermoelectric properties of molybdenum selenides containing Mo9 clusters have been investigated between 300 K and 800 K. Ag
x
Mo9Se11 (x = 3.4 and 3.8) have been synthesized by solid-state reaction and spark plasma sintering. X-ray diffraction and scanning electron
microscopy reveal high purity and good homogeneity of the samples. The thermoelectric power of the samples is positive over
the whole investigated temperature range, indicating that the majority of charge carriers are holes. The Seebeck coefficient
increases with temperature, and the temperature coefficient of the resistivity is positive. Significantly low thermal conductivity,
comparable to values reported for state-of-the-art thermoelectric materials, is observed in this new system, and this is assumed
to be associated with the rattling effect from the Ag filler atoms. It has been demonstrated that the electrical and thermal
properties correlate to the Ag concentration. For x = 3.8, a promising dimensionless thermoelectric figure of merit of ∼0.7 is obtained at 800 K. 相似文献
8.
S. Y. Wang W. J. Xie H. Li X. F. Tang Q. J. Zhang 《Journal of Electronic Materials》2011,40(5):1150-1157
A series of Bi2(Se0.4Te0.6)3 compounds were synthesized by a rapid route of melt spinning (MS) combined with a subsequent spark plasma sintering (SPS)
process. Measurements of the Seebeck coefficient, electrical conductivity, and thermal conductivity were performed over the
temperature range from 300 K to 520 K. The measurement results showed that the cooling rate of melt spinning had a significant
impact on the transport properties of electrons and phonons, effectively enhancing the thermoelectric properties of the compounds.
The maximum ZT value reached 0.93 at 460 K for the sample prepared with the highest cooling rate, and infrared spectrum measurement results
showed that the compound with lower tellurium content, Bi2(Se0.4Te0.6)3, possesses a larger optical forbidden gap (E
g) compared with the traditional n-type zone-melted material with formula Bi2(Se0.07Te0.93)3. Our work provides a new approach to develop low-tellurium-bearing Bi2Te3-based compounds with good thermoelectric performance. 相似文献
9.
S. Ceresara M. Codecasa F. Passaretti P. Tomeš A. Weidenkaff C. Fanciulli 《Journal of Electronic Materials》2011,40(5):557-560
A Bi-15 at.%Sb alloy, homogenized by equal channel angular extrusion (ECAE) at T = 523 K, has been treated just above its solidus temperature, causing segregation of a secondary Bi-rich phase at the grain
boundaries. This process results in an in situ composite. The thermoelectric properties of the composite have been measured in the range of 5 K < T < 300 K. The results are compared with those of the homogeneous alloy. The presence of a Bi-rich phase improves the Seebeck
coefficient at T < 50 K, and enhances the electrical conductivity by a factor of 1.4 at T = 300 K up to a factor of 3.4 at T = 50 K; unfortunately, the thermal conductivity also increases by about 50% in the same temperature range. As a result, the
figure of merit, Z, is slightly suppressed above T = 110 K, but increases at lower temperatures, reaching a peak value of 4.2 × 10−3 K−1 at T = 90 K. The power factor considerably increases over the whole temperature range, rendering this material suitable as the
n-type leg of a cryogenic thermoelectric generator for cold energy recovery in a liquefied natural gas plant. 相似文献
10.
H. L. Gao X. X. Liu T. J. Zhu S. H. Yang X. B. Zhao 《Journal of Electronic Materials》2011,40(5):830-834
This study focuses on Sb-doped Mg2(Si,Sn) thermoelectric material. Samples were successfully fabricated using a hybrid synthesis method consisting of three
different processes: induction melting, solid-state reaction, and a hot-press sintering technique. We found that the carrier
concentration increased with Sb content, while the Seebeck coefficient exhibited a decreasing trend. Sb doping was shown to
improve the power factor and thermoelectric figure of merit compared with the undoped material, yielding a peak figure of
merit (ZT) of ~0.55 at 620 K, while leaving the band gap of Mg2Si0.7Sn0.3 almost unchanged. 相似文献
11.
The results of studying the thermoelectric properties of p-type Bi0.5Sb1.5Te3 alloy samples prepared by melt spinning quenching are presented. The material after melt spinning is shaped as thin ribbons and has a quasi-amorphous structure. The thermoelectric properties (thermoelectric power and electrical resistance) and crystallization processes of as-prepared melt-spun ribbons are studied at 300–800 K for the first time. The stability range of the initial state, the crystallization-onset temperature, and the effect of thermal annealing on the thermoelectric-power factor of the alloy are determined. 相似文献
12.
Masaaki Isobe Masao Arai Eiji Takayama-Muromachi 《Journal of Electronic Materials》2009,38(7):1166-1170
In this work we studied the crystal structure and physical properties of the new one-dimensional cobalt oxide CaCo2O4+δ
. The CaCo2O4+δ
phase crystallizes as a calcium-ferrite-type structure, which consists of a corner- and edge-shared CoO6 octahedron network including one-dimensional double chains. The specific-heat Sommerfeld constant γ was found to be 4.48(7) mJ/mol K2. This result suggests that the CaCo2O4+δ
phase has a finite density of states at the Fermi level. Metallic temperature dependence of the Seebeck coefficient S with a large thermoelectric power (S = 151 μV/K at 387 K) was observed. The origin of the large thermoelectric power may be attributed to the quasi one-dimensional character
of the energy band near the valence band maximum in CaCo2O4+δ
. 相似文献
13.
Jiangying Peng Jian He Paola N. Alboni Terry M. Tritt 《Journal of Electronic Materials》2009,38(7):981-984
Filled skutterudites have long been singled out as one of the prime examples of phonon glass electron crystal materials. Recently
the double-filling approach in these materials has been attracting increased attention. In this study, Yb0.2In
y
Co4Sb12 (y = 0.0 to 0.2) samples have been prepared by a simple melting method and their thermoelectric properties have been investigated.
The power factor is increased dramatically when increasing the In content, while the lattice thermal conductivity is lowered
considerably, leading to a large increase of the ZT value. A state-of-the-art ZT value of 1.0 is attained in Yb0.2In0.2Co4Sb12 at 750 K. 相似文献
14.
J. Navrátil T. Plecháček L. Beneš Č. Drašar F. Laufek 《Journal of Electronic Materials》2010,39(9):1880-1884
A ternary ordered variant of the skutterudite structure, the Co4Sn6Se6 compound, was prepared. Polycrystalline samples were prepared by a modified ceramic method. The electrical conductivity,
the Seebeck coefficient and the thermal conductivity were measured over a temperature range of 300–800 K. The undoped Co4Sn6Se6 compound was of p-type electrical conductivity and had a band gap E
g of approximately 0.6 eV. The influence of transition metal (Ni and Ru) doping on the thermoelectric properties was studied.
While the thermal conductivity was significantly lowered both for the undoped Co4Sn6Se6 compound and for the doped compounds, as compared with the Co4Sb12 binary skutterudite, the calculated ZT values were improved only slightly. 相似文献
15.
Yanjie Cui James R. Salvador Jihui Yang Hsin Wang Gisele Amow Holger Kleinke 《Journal of Electronic Materials》2009,38(7):1002-1007
Three Ta-doped strontium titanates were prepared as potential candidates for n-type thermoelectric oxides. The purity of the polycrystalline samples of SrTi1−x
Ta
x
O3 (x = 0.05 to 0.14) were characterized by means of powder x-ray diffraction and electron probe micro analysis (EPMA). We present
the results of Seebeck coefficient, electrical conductivity, and thermal conductivity measurements performed at high temperatures. 相似文献
16.
Sin-Young Jung Tae-Jung Ha Won-Seon Seo Young Soo Lim Sangwoo Shin Hyung Hee Cho Hyung-Ho Park 《Journal of Electronic Materials》2011,40(5):652-656
Mesoporous materials have pores with diameters between 2 nm and 50 nm, the presence of which generally decreases the thermal
conductivity of the material. By incorporating mesoporous structures into thermoelectric materials, the thermoelectric properties
of these materials can be improved. Although TiO2 is an ordinary insulator, reduced TiO2 shows better electrical conductivity and is therefore a potential thermoelectric material. Furthermore, the addition of a
dopant to TiO2 can improve its electrical conductivity. We hypothesized that, by doping ordered mesoporous TiO2 films with niobium, we would be able to minimize the thermal conductivity and maximize the electrical conductivity. To investigate
the effects of Nb doping and a mesoporous structure on the thermoelectric characteristics of TiO2 films, Nb-doped mesoporous films were investigated using x-ray diffraction, ellipsometry, four-point probe measurements,
and thermal conductivity analysis. We found that Nb doping of ordered mesoporous TiO2 films improved their thermoelectric properties. 相似文献
17.
Ping Wei Wen-Yu Zhao Chun-Lei Dong Bing Ma Qing-Jie Zhang 《Journal of Electronic Materials》2010,39(9):1803-1808
Filled skutterudite thermoelectric (TE) materials have been extensively studied to search for better TE materials in the past
decade. However, there is no detailed investigation about the thermal stability of filled skutterudite TE materials. The evolution
of microstructure and TE properties of nanostructured skutterudite materials fabricated with Ba0.3In0.2Co3.95Ni0.05Sb12/SiO2 core–shell composite particles with 3 nm thickness shell was investigated during periodic thermal cycling from room temperature
to 723 K in this work. Scanning electronic microscopy and electron probe microscopy analysis were used to investigate the
microstructure and chemical composition of the nanostructured skutterudite materials. TE properties of the nanostructured
skutterudite materials were measured after every 200 cycles of quenching in the temperature range from 300 K to 800 K. The
results show that the microstructure and composition of Ba0.3In0.2Co3.95Ni0.05Sb12/SiO2 nanostructured skutterudite materials were more stable than those of single-phase Ba0.3In0.2Co3.95Ni0.05Sb12 bulk materials. The evolution of TE properties indicates that the electrical and thermal conductivity decrease along with
an increase in the Seebeck coefficient with increasing quenching up to 2000 cycles. As a result, the dimensionless TE figure
of merit (ZT) of the nanostructured skutterudite materials remains almost constant. It can be concluded that these nanostructured skutterudite
materials have good thermal stability and are suitable for use in solar power generation systems. 相似文献
18.
We have performed a detailed study of the electrical and thermal conductivities and thermoelectric power behavior of an antiferromagnetic-layer
compound of chromium, CuCrS2, from 15 K to 300 K. Unlike previous studies, we find noninsulating properties and sensitive dependence on the preparation
method, the microstructure, and the flaky texture formed in polycrystalline samples after extended sintering at high temperatures.
Flakes are found to be metallic, with strong localization effects in the conductivity on cooling to low temperatures. The
antiferromagnetic transition temperature T
N (=40 K) remains essentially unaffected. The Seebeck coefficient is found to be in the range of 150 μV/K to 450 μV/K, which is exceptionally large, and becomes temperature independent at high temperatures, even for specimens with low resistivity
values of 5 mΩ cm to 200 mΩ cm. We find the thermal conductivity κ to be low, viz. 5 mW/K cm to 30 mW/K cm. This can be attributed mostly to the dominance of lattice conduction over electronic
conduction. The value of κ is further reduced by disorder in Cu occupancy in the quenched phase. We also observe an unusually strong dip in κ at T
N, which is probably due to strong magnetocrystalline coupling in these compounds. Finally we discuss the properties of CuCrS2 as a heavily doped Kondo-like insulator in its paramagnetic phase. The combination of the electronic properties observed
in CuCrS2 makes it a potential candidate for various thermoelectric applications. 相似文献
19.
Peng-Peng Shang Bo-Ping Zhang Yong Liu Jing-Feng Li Hong-Min Zhu 《Journal of Electronic Materials》2011,40(5):926-931
Single-phase polycrystalline La
x
Sr1−x
TiO3 (x = 0, 0.04, 0.06, 0.08, and 0.12) ceramics were prepared by the conventional solid-state reaction method using high-activity
hydroxides as the raw materials. The electrical conductivity of all the samples increased with increasing x value and decreased with measurement temperature, while the thermal conductivity decreased with increasing x value and measurement temperature. The La0.12Sr0.88TiO3 sample showed the lowest thermal conductivity of 2.45 W m−1 K−1 at 873 K and the largest ZT of 0.28 at 773 K. The present work revealed that hydroxides with high activity as raw materials are beneficial to improve
the thermoelectric properties, especially to decrease the thermal conductivity. 相似文献
20.
Bulk thermoelectric nanocomposite materials have great potential to exhibit higher ZT due to effects arising from their nanostructure. Herein, we report low-temperature thermoelectric properties of Co0.9Fe0.1Sb3-based skutterudite nanocomposites containing FeSb2 nanoinclusions. These nanocomposites can be easily synthesized by melting and rapid water quenching. The nanoscale FeSb2 precipitates are well dispersed in the skutterudite matrix and reduce the lattice thermal conductivity due to additional
phonon scattering from nanoscopic interfaces. Moreover, the nanocomposite samples also exhibit enhanced Seebeck coefficients
relative to regular iron-substituted skutterudite samples. As a result, our best nanocomposite sample boasts a ZT = 0.041 at 300 K, which is nearly three times as large as that for Co0.9Fe0.1Sb3 previously reported. 相似文献