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1.
Zhong-wei Ruan Li-sheng Liu Peng-cheng Zhai Peng-fei Wen Qing-jie Zhang 《Journal of Electronic Materials》2010,39(9):2029-2033
An experimental study was carried out on CoSb3-based skutterudites. Tests were carried out at room temperature and in air. Firstly, static compression tests were conducted
to determine the compressive strength of the materials. Then stress-controlled low-cycle fatigue tests were performed using
a sinusoidal waveform of constant amplitude. The influence of the maximum stress on fatigue life was analyzed. The surfaces
and fracture surfaces of the specimens were observed by scanning electron microscopy. Fatigue crack initiation was observed
to occur from pre-existing defects in the specimen surface, and the fatigue fracture surface showed intergranular fracture
behavior. Finally, interrupted low-cycle fatigue tests were conducted to analyze residual strength degradation. 相似文献
2.
Jiong Yang L. Xi W. Zhang L. D. Chen Jihui Yang 《Journal of Electronic Materials》2009,38(7):1397-1401
We present an investigation of electronic structures and electrical transport properties of some filled CoSb3 skutterudites by combining ab initio projected augmented plane-wave calculations and Boltzmann transport theory with electron group velocity evaluated by the
momentum matrix method. The systems are studied in a 2 × 2 × 2 supercell of Co4Sb12 to reveal the effects induced by different filler atoms and their filling fractions. The temperature dependences of the Seebeck
coefficient and power factor are studied, and they are in good agreement with experimental data. Our results reveal an optimal
filling fraction for n-type filled CoSb3 skutterudites and related compounds for achieving the highest power factor values. 相似文献
3.
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
4.
P.N. Alboni X. Ji J. He N. Gothard J. Hubbard Terry M. Tritt 《Journal of Electronic Materials》2007,36(7):711-715
Because of their good electrical transport properties, skutterudites have been widely studied as potential next-generation
thermoelectric (TE) materials. One of the main obstacles to further improving their thermoelectric performance has been reducing
their relatively high thermal conductivity. To some extent, this hindrance has been partially resolved by filling the voids
found in the skutterudite structure with so-called “rattling” atoms. It has been predicted that reducing the dimensionality
in a TE material would have a positive effect in enhancing its thermoelectric properties, for example increasing the thermopower
and reducing the thermal conductivity. Introducing nanoparticles into the skutterudite materials could therefore have favorable
effects on their electrical properties and should also reduce lattice thermal conductivity by introducing extra scattering
centers throughout the sample. Nanoparticles may also be used in conjunction with void filling for further reduction of the
thermal conductivity of skutterudites. Cobalt triantimonide (CoSb3) samples with different amounts of embedded nanoparticles have been grown, and the electrical and thermal transport properties
for these composites have been measured from 10 K to 650 K. The synthetic techniques and electrical and thermal transport
data are discussed in this paper. 相似文献
5.
Pengfei Wen Peng Li Qingjie Zhang Fajun Yi Lisheng Liu Pengcheng Zhai 《Journal of Electronic Materials》2009,38(7):1200-1205
The effect of cyclic thermal loading on the microstructure and thermoelectric properties of CoSb3 was investigated. The microstructures of the samples were characterized by x-ray diffractometry, scanning electron microscopy,
energy dispersive x-ray spectrometry and density measurements. The electrical conductivity, the Seebeck coefficient and the
thermal conductivity were measured from room temperature to 800 K. Under cyclic thermal loading, antimony partially volatilized
from the surface of the sample, and the density obviously decreased. After 2000 cycles, the phase composition of the sample
remained stable, and the average grain size did not change significantly. Moreover, the electrical conductivity varied only
slightly, except in the low temperature region. The Seebeck coefficient decreased slightly. However, the thermal conductivity
changed remarkably with increasing numbers of thermal cycles. 相似文献
6.
Ch. Papageorgiou E. Hatzikraniotis Ch. B. Lioutas N. Frangis O. Valassiades K. M. Paraskevopoulos Th. Kyratsi 《Journal of Electronic Materials》2010,39(9):1665-1668
In this work, nanocrystalline lead telluride powder was synthesized from high-purity elements by mechanical alloying by means
of a planetary ball-milling procedure. The milling medium was tungsten carbide, and the diameter of the balls was varied in
order to investigate the effect on the structural features of the material. Phase transformations and crystallite evolution
during ball-milling were followed by powder x-ray diffraction (PXRD). The broadened PXRD peaks were analyzed with Voigt functions,
revealing small crystalline size and stress introduced during the mechanical alloying process. Transmission electron microscopy
(TEM) studies confirmed the material’s nanostructure, as well as the effect of ball diameter on the size of the crystals.
Thermoelectric properties are discussed in terms of the Seebeck coefficient and the nominal carrier concentration, as determined
by Hall-effect measurements. The enhancement of the Seebeck coefficient is reported to be higher compared with other PbTe-based
nanocomposites. 相似文献
7.
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
8.
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
9.
Chao Mei Yao Li Guodong Li Mingfa Li Pengcheng Zhai 《Journal of Electronic Materials》2009,38(7):1194-1199
The high-pressure sintering process is studied for the fabrication of the bulk CoSb3 thermoelectric material. The CoSb3 powder is prepared by a solid reaction method, and then the samples are sintered under high-pressure conditions. The emphasis
of the present study is on the influence of the pressure on the grain size and the electrical properties of the material.
For the present study, the pressure is taken to be from 1.5 GPa to 6 GPa, and the sintering temperature is 723 K. The experimental
results show that the major phase of skutterudite and traces of metal impurities of Sb and the CoSb2 phase coexist in some of the samples, and that the grain size of all the samples increase after sintering. In the range of
3.0 GPa to 6.0 GPa, the grain size increases with increasing pressure. In the range of 1.5 GPa to 3.0 GPa, the grain size
also increases, but with a diminishing growth rate. All the materials show p-type transport behaviors, and the sample sintered under 2.0 GPa shows higher electrical conductivity than the 5.7 GPa sample,
which may be due to the impurities. 相似文献
10.
An Zhou Li-sheng Liu Peng-cheng Zhai Wen-yu Zhao Qing-jie Zhang 《Journal of Electronic Materials》2010,39(9):1832-1836
Band structure and density of states (DOS) of CoSb3 single-filled by seven kinds of atoms (R0.125Co4Sb12) are calculated by the density functional method. The results for the electronic structures in turn determine the electrical
transport and thermal performance. It is found that the band structure of R0.125Co4Sb12 shows no significant changes compared with that of CoSb3, and the results indicate that void filling with a small quantity of R atoms does not change the bond formation in CoSb3. However, the partial DOS reveals that there could be interaction of Sn, Tl, In, and Yb atoms with CoSb3. The results for the electrical transport properties and thermal properties show that Sn, Tl, and In atoms increase the Seebeck
coefficient and La, Eu, and Yb atoms are helpful for increasing the electron concentration and decreasing the thermal conductivity
further. According to our calculations and Yang’s principle, double-filled CoSb3 with atomic combinations of (In, Ca), (In, Ba), (Sn, Eu), and (Sn, La) may exhibit good thermoelectric performance. 相似文献
11.
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
12.
D. G. Ebling A. Jacquot H. Böttner L. Kirste J. Schmidt M. Aguirre 《Journal of Electronic Materials》2009,38(7):1450-1455
Thermoelectric compounds based on doped bismuth telluride and its alloys have recently attracted increasing interest. Due
to their structural features they show increased values of the thermoelectric figure of merit (ZT). A promising approach to improve the thermoelectric properties is to manufacture nanocomposite materials exhibiting lower
thermal conductivities and higher ZT. The ZT value of compounds can be shifted reasonably to higher values (>1) by alloying with IV-Te materials and adequate preparation
methods to form stable nanocomposites. The influence of PbTe and Sn on the thermoelectric properties is studied as a function
of concentration and preparation methods. Melt spinning and spark plasma sintering were applied to form nanocomposite materials
that were mechanically and thermodynamically stable for applications in thermoelectric devices. The structural properties
are discussed based on analysis by transmission electron microscopy and x-ray diffraction. 相似文献
13.
Xuqiu Yang Lisheng Liu Qingjie Zhang Pengcheng Zhai 《Journal of Electronic Materials》2011,40(5):489-492
Molecular dynamics simulations of the structural and mechanical properties of single-crystalline CoSb3 have been carried out at room temperature. Special emphasis was given to the surface effect. Four different boundary conditions
were applied to represent a wide range of surface-atom fractions. The LAMMPS program in conjunction with a multibody potential
was employed. First, free relaxation was performed to obtain the corresponding stable configurations. The atomic rearrangements
and energy distributions were observed. Then, uniaxial tensile deformation was simulated at a constant strain rate. The stress–strain
responses and structural evolutions were examined during the process. Comparison of simulation results between different boundary
conditions was carefully made. It was found that, when the scale of the single-crystalline CoSb3 model becomes nanometric and the fraction of the surface atoms increases, the mechanical performance becomes substantially
worse. Nonetheless, the deformation mechanism and intrinsic mechanical nature are very similar. 相似文献
14.
We have prepared Ni- and Mg-substituted LaRhO3 and have measured the thermoelectric properties. Ni substitution decreases resistivity at room temperature, while Mg substitution
decreases resistivity up to 5%, where the Mg substitution increases the carrier concentration, as confirmed by Hall coefficient
measurements. 相似文献
15.
Ja Young Cho Young Soo Lim Soon-Mok Choi Kyoung Hun Kim Won-Seon Seo Hyung-Ho Park 《Journal of Electronic Materials》2011,40(5):1024-1028
We report the thermoelectric properties of spark plasma-sintered In4Se3-In4Te3 materials. For comparison, pure In4Se3 and In4Se3 (80 wt.%)/In4Te3 (20 wt.%) mixture samples were prepared. In4Se3 and In4Te3 powders were synthesized by a conventional melting process in evacuated quartz ampoules, and a spark plasma method was used
for the sintering of the pure In4Se3 and mixture samples. Thermoelectric and structural characterizations were carried out, and the mixing effect of In4Se3 and In4Te3 on the thermoelectric properties was investigated. 相似文献
16.
Cu0.003Bi0.4Sb1.6Te3 alloys were prepared by using encapsulated melting and hot extrusion (HE). The hot-extruded specimens had the relative average density of 98%. The (00l) planes were preferentially oriented parallel to the extrusion direction, but the specimens showed low crystallographic anisotropy with low orientation factors. The specimens were hot-extruded at 698 K, and they showed excellent mechanical properties with a Vickers hardness of 76 Hv and a bending strength of 59 MPa. However, as the HE temperature increased, the mechanical properties degraded due to grain growth. The hot-extruded specimens showed positive Seebeck coefficients, indicating that the specimens have p-type conduction. These specimens exhibited negative temperature dependences of electrical conductivity, and thus behaved as degenerate semiconductors. The Seebeck coefficient reached the maximum value at 373 K and then decreased with increasing temperature due to intrinsic conduction. Cu-doped specimens exhibited high power factors due to relatively higher electrical conductivities and Seebeck coefficients than those of undoped specimens. A thermal conductivity of 1.00 Wm?1 K?1 was obtained at 373 K for Cu0.003Bi0.4Sb1.6Te3 hot-extruded at 723 K. A maximum dimensionless figure of merit, ZT max = 1.05, and an average dimensionless figure of merit, ZT ave = 0.98, were achieved at 373 K. 相似文献
17.
C. Candolfi U. Aydemir M. Baitinger N. Oeschler F. Steglich Yu. Grin 《Journal of Electronic Materials》2010,39(9):2039-2042
The clathrate I Ba8Ge43□3 [space group Ia[`3]d Ia\bar{3}d , no. 230, a = 21.307(1) ?] has been synthesized as a single phase and characterized by x-ray powder diffraction and metallographic analysis.
Electrical and thermal transport measurements have been performed in the temperature range of 5 K to 673 K. Ba8Ge43□3 displays the electrical resistivity of a poor metal at low temperatures, with semiconducting-like behavior appearing above
300 K. 相似文献
18.
Ternary palladates CdPd3O4 and TlPd3O4 have been studied theoretically using the generalized gradient approximation (GGA), modified Becke–Johnson, and spin–orbit coupling (GGA–SOC) exchange–correlation functionals in the density functional theory (DFT) framework. From the calculated ground-state properties, it is found that SOC effects are dominant in these palladates. Mechanical properties reveal that both compounds are ductile in nature. The electronic band structures show that CdPd3O4 is metallic, whereas TlPd3O4 is an indirect-bandgap semiconductor with energy gap of 1.1 eV. The optical properties show that TlPd3O4 is a good dielectric material. The dense electronic states, narrow-gap semiconductor nature, and Seebeck coefficient of TlPd3O4 suggest that it could be used as a good thermoelectric material. The magnetic susceptibility calculated by post-DFT treatment confirmed the paramagnetic behavior of these compounds. 相似文献
19.
Zhen-Hua Ge Bo-Ping Zhang Peng-Peng Shang Yi-Qiang Yu Chen Chen Jing-Feng Li 《Journal of Electronic Materials》2011,40(5):1087-1094
Bismuth sulfide (Bi2S3) polycrystalline samples were fabricated by mechanical alloying (MA) combined with spark plasma sintering (SPS). The microstructure
and electrical transport properties were investigated with special emphasis on the influence of the ball-milling process.
Bi2S3 compound powders could be readily synthesized directly from elemental powders under all the investigated conditions, and
highly dense n-type bulk Bi2S3 samples with high density (>95%) were fabricated by the subsequent SPS process. Changing the MA conditions had no apparent
influence on the microstructure or phase structure of the MA-derived Bi2S3 powders, but the electrical properties and thermopower of the SPS-sintered Bi2S3 bulk samples were greatly dependent on the MA speed and time. The power factor of Bi2S3 was increased to 233 μW K−2 m−1 at 573 K by optimizing the ball-milling process. This power factor is higher than values reported to date for Bi-S binary
samples without texture. 相似文献
20.
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