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1.
Ba+Yb double-filled n-type skutterudites with a modest degree of charge compensation by Fe on the Co lattice have been synthesized and compacted
by spark-plasma sintering, and their thermoelectric properties evaluated at temperatures up to 800 K. Although this approach
to making n-type skutterudites seems counterintuitive, the presence of Fe leads to a reduction in the thermal conductivity while it
preserves a robust Seebeck coefficient. Consequently, a high ZT in excess of 1.3 was achieved at 800 K in these Fe-containing n-type skutterudite compounds. 相似文献
2.
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
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.
Ca
z
Co4−x
(Fe/Mn)
x
Sb12 skutterudites were prepared by mechanical alloying and hot pressing. The phases of mechanically alloyed powders were identified
as γ-CoSb2 and Sb, but they were transformed to δ-CoSb3 by annealing at 873 K for 100 h. All specimens had a positive Hall coefficient and Seebeck coefficient, indicating p-type conduction by holes as majority carriers. For the binary CoSb3, the electrical conductivity behaved like a nondegenerate semiconductor, but Ca-filled and Fe/Mn-doped CoSb3 showed a temperature dependence of a degenerate semiconductor. While the Seebeck coefficient of intrinsic CoSb3 increased with temperature and reached a maximum at 623 K, the Seebeck coefficient increased with increasing temperature
for the Ca-filled and Fe/Mn-doped specimens. Relatively low thermal conductivity was obtained because fine particles prepared
by mechanical alloying lead to phonon scattering. The thermal conductivity was reduced by Ca filling and Fe/Mn doping. The
electronic thermal conductivity was increased by Fe/Mn doping, but the lattice thermal conductivity was decreased by Ca filling.
Reasonable thermoelectric figure-of-merit values were obtained for Ca-filled Co-rich p-type skutterudites. 相似文献
5.
J. Leszczynski A. Dauscher P. Masschelein B. Lenoir 《Journal of Electronic Materials》2010,39(9):1764-1768
Interesting results for cobalt triantimonide partially filled with indium have encouraged us to explore skutterudites filled
with higher indium fractions. For pure In
x
Co4Sb12, the fraction of voids filled is limited to about x = 0.25. To enable the insertion of more indium atoms, charge compensation is necessary. In this work, we studied the skutterudite
compound In
x
Fe
y
Co4−y
Sb12 partially filled with indium, where iron substitution for cobalt was employed for charge compensation. Polycrystalline samples
were prepared by direct reaction of constituents. Structural and chemical characterization were accomplished by x-ray diffraction
and energy-dispersive x-ray spectroscopy. Electrical resistivity, thermoelectric power, and thermal conductivity were measured
between 2 K and 350 K. The influence of indium and iron on the charge-carrier transport properties and thermal conductivity
in In
x
Fe
y
Co4−y
Sb12 compounds is presented and discussed. 相似文献
6.
Indium-filled skutterudites are promising power generation thermoelectric materials due to the presence of an InSb nanostructure
that lowers the thermal conductivity. In this work, we have investigated thermoelectric properties of triple-filled Ba
x
Yb
y
In
z
Co4Sb12 (0 ≤ x, y, z ≤ 0.14 actual) compounds by measuring their Seebeck coefficient, electrical conductivity, thermal conductivity, and Hall
coefficient. All samples were prepared by a melting–annealing–spark plasma sintering method, and their structure was characterized
by x-ray diffraction and transmission electron microscopy (TEM). TEM results show the development of an InSb nanostructure
with a grain size of 30 nm to 500 nm. The nanostructure is present in all samples containing In and is also detected by specific
heat measurements. The Seebeck and Hall coefficients indicate that the compounds are n-type semiconductors. Electrical conductivity increases with increasing Ba content. Thermal conductivity is strongly suppressed
upon the presence of In in the skutterudite structure, likely due to enhanced boundary scattering of phonons on the nanometer-scale
InSb inclusions. The highest thermoelectric figure of merit is achieved with Ba0.09Yb0.07In0.06Co4Sb11.97, reaching ZT = 1.25 at 800 K. 相似文献
7.
The thermoelectric figure of merit ZT of materials limits the performance of a thermoelectric power generator. To date, the main gains from the worldwide effort
in either engineered bulk materials or low-dimensional systems have been mostly based on the strategies of reducing the thermal
conductivity. We explore several bulk thermoelectric materials that have respectable mecha- nical strength and chemical stability
at elevated temperatures for potential power generation. Our strategy is to first explore the avenue of significantly increasing
the power factor (PF), then the avenue of lowering thermal conductivity, perhaps by nanocompositing. We examine the layered
cobaltates with sharp resonant peaks in the electronic density of states near the Fermi energy level due to strong electron
correlation. We suggest that electron correlation may be used as a new tuning parameter to significantly increase the PF.
We also report that a substantial increase (over 30%) in PF can be achieved in filled skutterudites (such as p-type CeFe4Sb12) through nonequilibrium synthesis by rapid conversion of the amorphous materials made by the melt spinning to single-phase
crystalline materials under pressure. This process, in conjunction with the rattling to lower the lattice thermal conductivity,
could further enhance the ZT values of the filled skutterudites. 相似文献
8.
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
9.
Development of Skutterudite Thermoelectric Materials and Modules 总被引:2,自引:0,他引:2
J. Q. Guo H. Y. Geng T. Ochi S. Suzuki M. Kikuchi Y. Yamaguchi S. Ito 《Journal of Electronic Materials》2012,41(6):1036-1042
Multifilling with La, Ba, Ga, and Ti in p-type skutterudite and Yb, Ca, Al, Ga, and In in n-type skutterudite remarkably reduces their thermal conductivity, resulting in enhancement of their dimensionless figure of merit ZT to ZT?=?0.75 for p-type (La,Ba,Ga,Ti)1(Fe,Co)4Sb12 and ZT?=?1.0 for n-type (Yb,Ca,Al,Ga,In)0.7(Co,Fe)4Sb12. A thermoelectric module technology suitable for these skutterudites including diffusion barrier and electrode materials has been established. The diffusion barrier materials allow the electrode to coexist stably with the p/n skutterudites in the module??s working temperature range of room temperature to 600°C. Under conditions of hot/cold-side temperatures of 600°C/50°C, a skutterudite module with size of 50?mm?×?50?mm?×?7.6?mm exhibited generation performance of 32?W power output and 8% thermoelectric conversion efficiency. 相似文献
10.
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
11.
Jennifer Graff Song Zhu Tim Holgate Jiangying Peng Jian He Terry M. Tritt 《Journal of Electronic Materials》2011,40(5):696-701
Void-filling in the CoSb3 skutterudite lattice with different kinds of heavy elements has proven to be an effective mechanism to enhance thermoelectric
performance due primarily to a reduction in lattice thermal conductivity. Specifically, our findings on the series In
x
Yb
y
Co4Sb12 [0 ≤ (x, y) ≤ 0.2] have further motivated an attempt to form triple-filled skutterudites Ce0.1In
x
Yb
y
Co4Sb12 with In and Yb concentrations [0 ≤ (x, y) ≤ 0.2] and with the Ce concentration held constant (Ce0.1). All of these samples have been prepared via a simplified melting–annealing–sintering procedure and were first characterized
by means of x-ray powder diffraction and scanning electron microscopy, followed by measurements of the Hall coefficient, electrical
and thermal conductivities, and Seebeck coefficient. Our aim is to further elucidate the roles of the three elements (Ce,
In, and Yb) in these materials. Compared with the addition of just In or Yb, we found that simultaneous addition of both In
and Yb reduced the lattice thermal conductivity without significantly degrading the power factor. Further addition of the
third element (Ce), along with In and Yb, also produced a similar result. However, we noticed that some of the In and Yb were
also observed in the form of secondary phases (InSb and Yb2O3), not entering entirely as filler atoms. As a result of our investigation, several compositions achieved increased sustainability
and enhanced thermoelectric performance, with maximum ZT values of about 1.3 to 1.4 obtained at around 800 K. 相似文献
12.
Jian Yu Wen-Yu Zhao Xuan Yang Ping Wei Ding-Guo Tang Qing-Jie Zhang 《Journal of Electronic Materials》2012,41(6):1395-1400
A series of (Ba,In) double-filled n-type skutterudite materials with nominal composition Ba0.4In m Co4Sb12 (m?=?0 to 0.4, ??m?=?0.1) has been prepared by melt quenching, annealing, and spark plasma sintering (SPS). The presence of In impurity and its effect on the thermoelectric properties of the filled skutterudite materials have been precisely investigated in this work. All samples consisted of skutterudite phase, while traces of In-containing impurity were detected in samples with m????0.3. The electrical conductivity and thermal conductivity decreased, and the absolute value of the Seebeck coefficient increased with increasing m in the range 0 to 0.2; however, the inverse behavior of the electrical conductivity, thermal conductivity, and Seebeck coefficient was observed in the samples with m????0.3. The thermoelectric properties of Ba0.4In m Co4Sb12 in the m range of 0 to 0.2 were changed because of carrier concentration degradation and strong lattice scattering induced by the In filler, while they were intensively affected by the In-containing impurity for m????0.3. Compared with the Ba single-filled skutterudite material, the power factors of all (Ba,In) double-filled skutterudite materials significantly increased and the lattice thermal conductivity dramatically decreased. As a result, two large ZT values for the samples with m?=?0.2 and 0.4 reached 1.19 and 1.25 at 800?K, which is an enhancement of 52% and 60%, respectively. 相似文献
13.
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
14.
A. V. Shevelkov E. A. Kelm A. V. Olenev V. A. Kulbachinskii V. G. Kytin 《Semiconductors》2011,45(11):1399-1403
Single-crystal samples of cationic clathrates in the Sn-In-As-I system with different indium contents have been synthesized.
Their crystal structure has been analyzed and their thermoelectric properties have been measured. These compounds are found
to be n-type semiconductors with high absolute values of the Seebeck coefficient (S = 400–600 μV/K) and anomalously low thermal conductivity (κ ≤ 0.4 W/(m/K) at 300 K, which is characteristic of amorphous
materials. The reasons for the anomalously low thermal conductivity of these semiconductors are discussed and ways for optimizing
their thermoelectric properties are shown. 相似文献
15.
XianLi Su Han Li QuanSheng Guo Xinfeng Tang Qingjie Zhang Ctirad Uher 《Journal of Electronic Materials》2011,40(5):1286-1291
n-Type CoSb2.875−x
Ge0.125Te
x
(x = 0.125 to 0.275) compounds with different Te contents have been synthesized by a melt–quench–anneal–spark plasma sintering
method, and the effects of Te content on the structure and thermoelectric properties have been investigated. The results show
that all specimens exhibited n-type conduction characteristics. The solubility limit of Te in CoSb2.875−x
Ge0.125Te
x
is found to be x = 0.25. The solubility of Te in CoSb3 is increased through charge compensation of the element Ge. The room-temperature carrier concentration N
p of CoSb2.875−x
Ge0.125Te
x
skutterudites increases with increasing Te content, and the compounds possess high power factors. The maximum power factor
of 3.89 × 10−3 W m−1 K−2 was obtained at 720 K for the CoSb2.625Ge0.125Te0.25 compound. The thermal conductivity decreases dramatically with increasing Te content due to strong point defect scattering.
The maximum value of the thermoelectric figure of merit ZT = 1.03 was obtained at 800 K for CoSb2.625Ge0.125Te0.25, benefiting from a lower thermal conductivity and a higher power factor. The figure of merit is competitive with values reported
for single-filled skutterudites. 相似文献
16.
Neophytos Neophytou Martin Wagner Hans Kosina Siegfried Selberherr 《Journal of Electronic Materials》2010,39(9):1902-1908
Low-dimensional materials provide the possibility of improved thermoelectric performance due to the additional length scale
degree of freedom for engineering their electronic and thermal properties. As a result of suppressed phonon conduction, large
improvements in the thermoelectric figure of merit, ZT, have recently been reported in nanostructures, compared to the raw materials. In addition, low dimensionality can improve
a device’s power factor, offering an additional enhancement in ZT. In this work the atomistic sp3d5s* spin-orbit-coupled tight-binding model is used to calculate the electronic structure of silicon nanowires (NWs). The Landauer
formalism is applied to calculate an upper limit for the electrical conductivity, the Seebeck coefficient, and the power factor.
We examine n-type and p-type nanowires with diameters from 3 nm to 12 nm, in [100], [110], and [111] transport orientations, at different doping
concentrations. Using experimental values for the lattice thermal conductivity in nanowires, an upper limit for ZT is computed. We find that at room temperature, scaling the diameter below 7 nm can at most double the power factor and enhance
ZT. In some cases, however, scaling does not enhance the performance at all. Orientations, geometries, and subband engineering
techniques for optimized designs are discussed. 相似文献
17.
Te-doped Mg2Si (Mg2Si:Te
m
, m = 0, 0.01, 0.02, 0.03, 0.05) alloys were synthesized by a solid-state reaction and mechanical alloying. The electronic transport
properties (Hall coefficient, carrier concentration, and mobility) and thermoelectric properties (Seebeck coefficient, electrical
conductivity, thermal conductivity, and figure of merit) were examined. Mg2Si was synthesized successfully by a solid-state reaction at 673 K for 6 h, and Te-doped Mg2Si powders were obtained by mechanical alloying for 24 h. The alloys were fully consolidated by hot-pressing at 1073 K for
1 h. All the Mg2Si:Te
m
samples showed n-type conduction, indicating that the electrical conduction is due mainly to electrons. The electrical conductivity increased
and the absolute value of the Seebeck coefficient decreased with increasing Te content, because Te doping increased the electron
concentration considerably from 1016 cm−3 to 1018 cm−3. The thermal conductivity did not change significantly on Te doping, due to the much larger contribution of lattice thermal
conductivity over the electronic thermal conductivity. Thermal conduction in Te-doped Mg2Si was due primarily to lattice vibrations (phonons). The thermoelectric figure of merit of intrinsic Mg2Si was improved by Te doping. 相似文献
18.
P. Tomeš R. Robert M. Trottmann L. Bocher M. H. Aguirre A. Bitschi J. Hejtmánek A. Weidenkaff 《Journal of Electronic Materials》2010,39(9):1696-1703
Novel thermoelectric oxides were developed, produced, and characterized to demonstrate their promising thermoelectric conversion
potential in a thermoelectric converter. Four-leg thermoelectric oxide modules were fabricated by combining p- and n-type oxide thermoelements made of pressed polycrystalline GdCo0.95Ni0.05O3 and CaMn0.98Nb0.02O3, respectively. In these modules, the p- and n-type thermoelements were connected electrically in series and thermally in parallel. The materials were joined by electrical
contacts consisting of a Ag/CuO composite material. Fairly good thermal contacts were ensured by pressing the thermoelements
between alumina substrates. Cross-sections of the alumina/Ag–CuO mixture/thermoelement interface were investigated by scanning
electron microscopy. The temperature distribution across the module was monitored using K-type thermocouples and a micro-infrared
(IR) camera. The open-circuit voltage and the load voltages of the module were measured up to a temperature difference of
ΔT = 500 K while keeping the temperature of the cold side at 300 K. The output power and internal resistance were calculated.
The characteristics of the module evaluated from electrical measurements were compared with respective values of the p- and n-type leg materials. An output power of 0.04 W at ΔT = 500 K led to a power density of ~0.125 W/cm3, where the volume of thermoelectric material was determined by a cross-section of 4 mm × 4 mm and a leg length of 5 mm. 相似文献
19.
Sung-Do Kwon Byeong-kwon Ju Seok-Jin Yoon Jin-Sang Kim 《Journal of Electronic Materials》2009,38(7):920-924
Bismuth–antimony–telluride based thin film materials were grown by metal organic vapor phase deposition (MOCVD). A planar-type
thermoelectric device was fabricated with p-type Bi0.4Sb1.6Te3 and n-type Bi2Te3 thin films. The generator consisted of 20 pairs of p-type and n-type legs. We demonstrated complex structures of different conduction types of thermoelectric elements on the same substrate
using two separate deposition runs of p-type and n-type thermoelectric materials. To demonstrate power generation, we heated one side of the sample with a heating block and
measured the voltage output. An estimated power of 1.3 μW was obtained for the temperature difference of 45 K. We provide a promising procedure for fabricating thin film thermoelectric
generators by using MOCVD grown thermoelectric materials that may have a nanostructure with high thermoelectric properties. 相似文献
20.
Wenhao Fan Ruixue Chen Liqi Wang Peide Han Qingsen Meng 《Journal of Electronic Materials》2011,40(5):1209-1214
The thermoelectric properties of Y-doped (1000 ppm, 2000 ppm, 3000 ppm) Mg2Si fabricated using field-activated pressure-assisted synthesis (FAPAS) have been characterized using measurements of electrical
resistivity (ρ), Seebeck coefficient (S), and thermal conductivity (κ) at temperatures ranging from 285 K to 810 K. The Y-doped Mg2Si samples were n-type in the measured temperature range. A first-principles calculation revealed that the Y atoms were expected to be primarily
located at Mg sites. In sample doped with 2000 ppm Y, which exhibited the best electrical and thermal conductivity, the absolute
value of the Seebeck coefficient increased in the temperature range of 320 K to 680 K, being higher than that of undoped Mg2Si. Moreover, this sample exhibited a higher level of electrical conductivity and a higher power factor. In addition, introduction
of Y decreased the thermal conductivity appreciably, indicating that Y dopants are favorable for improving the properties
of Mg2Si. 相似文献