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1.
In order to improve the thermoelectric properties via efficient phonon scattering Didymium (DD), a mixture of Pr and Nd, was used as a new filler in ternary skutterudites (Fe1−xCox)4Sb12 and (Fe1−xNix)4Sb12. DD-filling levels have been determined from combined data of X-ray powder diffraction and electron microprobe analyses (EMPA). Thermoelectric properties have been characterized by measurements of electrical resistivity, thermopower and thermal conductivity in the temperature range from 4.3 to 800 K. The effect of nanostructuring in DD0.4Fe2Co2Sb12 was elucidated from a comparison of both micro-powder (ground in a WC-mortar, 10 μm) and nano-powder (ball-milled, 150 nm), both hot pressed under identical conditions. The figure of merit ZT depends on the Fe/Co and Ni/Co-contents, respectively, reaching ZT > 1. At low temperatures the nanostructured material exhibits a higher thermoelectric figure of merit. The Vickers hardness was measured for all samples being higher for the nanostructured material. 相似文献
2.
《Intermetallics》2016
Bi2Te3−xSex alloys are extensively used for thermoelectric cooling around room temperature, but, previous studies have reported peak thermoelectric efficiency of the material at higher temperature around 450 K. This study presents the casting followed by high energy ball milling and spark plasma sintering as a thriving methodology to produce efficient and well-built Bi2Te3−xSex material for the thermoelectric cooling around room temperature. In addition, changes in electrical and thermal transport properties brought up by amount of Se in the Bi2Te3−xSex material for this methodology are measured and discussed. Although Seebeck coefficient and electrical conductivity showed irregular trend, power factor, thermal conductivity and figure of merit ZT gradually decreased with the increase in amount of Se. A maximum ZT value of 0.875 at 323 K was obtained for x = 0.15 sample owing to its higher power factor. This value is 17% and 38% greater than for x = 0.3 and x = 0.6 samples respectively. At 323 K, herein reported ZT value of 0.875 is higher than the state of art n-type Bi2Te3 based thermoelectric materials produced by the time consuming and expensive methodologies. 相似文献
3.
K. Yang H. Cheng H.H. Hng J. Ma J.L. Mi X.B. Zhao T.J. Zhu Y.B. Zhang 《Journal of Alloys and Compounds》2009,467(1-2):528-532
Ce–Yb double-filled skutterudites Ce0.5?yYbyFe1.5Co2.5Sb12 (y = 0.1, 0.2, 0.4 and 0.5) were synthesized by a melting method with subsequent annealing. The thermal conductivity, electrical conductivity and Seebeck coefficient were measured from room temperature up to 773 K. The thermal conductivities of all the double-filled skutterudites were found to be lower than the Yb single-filled skutterudites. An enhancement in the dimensionless thermoelectric figure of merit ZT was also observed in all the double-filled skutterudites as compared to the Yb single-filled skutterudite. Ce0.3Yb0.2Fe1.5Co2.5Sb12 has the highest dimensionless figure of merit ZT of 0.32 at 723 K, which is 55% higher than the Yb single-filled skutterudite at the same temperature. 相似文献
4.
Gerda Rogl Andriy Grytsiv Peter Rogl Esmaeil Royanian Ernst Bauer Jelena Horky Daria Setman Erhard Schafler Michael Zehetbauer 《Acta Materialia》2013,61(18):6778-6789
High-pressure torsion (HPT), a severe plastic deformation technique, can effectively improve the thermoelectric performance of skutterudites, resulting in ZT values higher than for ball-milled and hot-pressed (BMHP) samples. In this paper the influence of the HPT parameters, i.e. the number of revolutions (equivalent to the applied strain), the processing temperature and the hydrostatic pressure on the microstructural and thermoelectric properties of the skutterudite DD0.60Fe3CoSb12 are evaluated and compared with the BMHP samples before HPT processing. Whilst the three parameters have specific effects on (i) the crystallite size, (ii) the density of lattice defects and (ii) the density of cracks, a suitable combination thereof allows for an increase of the figure of merit by at least 20%. 相似文献
5.
Hot-pressed samples of the semi-conducting compound Zn4Sb3 with the stoichiometric composition were prepared and characterized by X-ray and microprobe analysis. Thermoelectric characterization was done through measurements of the electrical and thermal conductivities as well as the Seebeck coefficient between room temperature and 650 K. All samples had p-type conductivity. High thermoelectric figures of merit (ZT) were obtained between 450 and 650 K and a maximum of about 1.3 were obtained at a temperature of 650 K. 相似文献
6.
Hot-pressed samples of the semi-conducting compound CoSb3-doped Pd and Te were prepared and characterized by X-ray and microprobe analysis. Thermoelectric characterization was done through measurements of the electrical and thermal conductivities as well as the Seebeck coefficient between room temperature and 900 K. All samples had n-type conductivity. The dimensionless thermoelectric figure of merit ZT increases with increasing temperature and reaches a maximum value of 1 at 873 K. 相似文献
7.
Sn-filled (Fe, Co)Sb3 skutterudites of the form of SnyFe3Co5Sb24 (0≤y≤1.5) were synthesized by the mechanical alloying of elemental powders followed by vacuum hot pressing. The phase transformations
that occur during both mechanical alloying and vacuum hot pressing were examined by X-ray diffraction. Single-phase Sn-filled
skutterudite was successfully produced by vacuum hot pressing using as-milled powders without subsequent annealing. The thermoelectric
properties of the hot-pressed specimens were evaluated as a function of temperature and tin content. The void filling of tin
(up to y=1.0) in Fe3Co5Sb24 appeared to increase the thermoelectric figure of merit. 相似文献
8.
While intensive work has been done on n-type Yb filled skutterudites in the past, very little is known about their p-type counterparts for potential applications as thermoelectric materials. In this paper, we report a systematic study of high temperature thermoelectric transport properties of p-type Yb-filled Fe-compensated skutterudites YbxFeyCo4-ySb12 with the aim to complement the knowledge base for the Yb-filled skutterudite family. The highest ZTmax = 0.6 was found in Yb0.6Fe2Co2Sb12 at 782 K. YbFe4Sb12 exhibits the second highest ZTmax = 0.57 at 780 K, which is much higher than the previous estimate of 0.4 for the same composition. 相似文献
9.
H. Ihou-Mouko C. MercierJ. Tobola G. PontH. Scherrer 《Journal of Alloys and Compounds》2011,509(23):6503-6508
Mg2Si:Gax and Mg2Si0.6Ge0.4:Gax (x = 0.4% and 0.8%) solid solutions have been synthesized by direct melting in tantalum crucibles and hot pressing. The effect of Ga doping on the thermoelectric properties has also been investigated by measurements of thermopower, electrical resistivity, Hall coefficient and thermal conductivity in temperature range from 300 to 850 K. All samples exhibit a p-type conductivity evidenced by positive sign of both thermopower and Hall coefficient in the investigated temperatures. The maximum value of the dimensionless figure of merit ZT was reached for the Mg2Si0.6Ge0.4:Ga(0.8%) compound at 625 K (ZT ∼ 0.36). The p-type character of thermoelectric behaviours of Ga-doped Mg2Si and Mg2Si0.6Ge0.4 compounds well corroborates with the results of electronic structure calculations performed by the Korringa-Kohn-Rostoker method and the coherent potential approximation (KKR-CPA), since Ga diluted in Mg2Si and Mg2Si0.6Ge0.4 (on Si/Ge site) behaves as hole donor due to the Fermi level shifted to the valence band edge. The onset of large peak of DOS from Ga impurity at the valence band edge, well corroborates with high Seebeck coefficient measured in Ga-doped samples. 相似文献
10.
G. Rogl A. Grytsiv M. Falmbigl E. Bauer C. Mangler C. Rentenberger M. Zehetbauer P. Rogl 《Acta Materialia》2012,60(11):4487-4495
The thermoelectric and structural properties of a double filled skutterudite solid solution (CaxBa1?x)yFe4Sb12 were investigated. Using X-ray powder and X-ray micro analyses (EPMA) an immiscibility gap was established with a critical point at x ≈ 0.45 and a critical temperature that depends on the filling level (TC = 590 ± 5 °C at y = 0.8 and TC = 610 ± 5 °C at y = 0.9). The thermoelectric properties were measured for samples prepared in four different states: (i) a single phase solid solution (CaxBa1?x)yFe4Sb12; (ii) a two phase microcrystalline mixture of CayFe4Sb12 and BayFe4Sb12; (iii) a single phase structure obtained after annealing of the latter sample at 600 °C for 200 h; (iv) a spinodally demixed sample after annealing at 400 °C for 672 h. The thermoelectric properties of the phase mixture (ii) are compatible with data reported for the microcrystalline end members (CayFe4Sb12 and BayFe4Sb12), whilst the single phase (i and iii) and spinodally decomposed (iv) samples show increased thermopower and decreased thermal conductivity, similarly to those observed for nano-structured CayFe4Sb12 and BayFe4Sb12. 相似文献
11.
Wei Li Limei Zhou Yali Li Jun Jiang Gaojie Xu 《Journal of Alloys and Compounds》2009,486(1-2):335-337
A series of samples have been fabricated through vacuum melting method followed by hot-pressing for Zn4Sb3−xTex (x = 0.02–0.08), XRD patterns indicated that all the samples were single-phased β-Zn4Sb3. Electrical conductivity and Seebeck coefficient were evaluated in the temperature range of 300–700 K, showing p-type conduction. The thermoelectric figure of merit (ZT) was increased with the increase of Te content. ZT values of 0.8 and 1.0 were obtained at 673 K for Zn4.08Sb3 and Zn4Sb2.92Te0.08, respectively. 相似文献
12.
High performance (Bi2Te3)x(Sb2Te3)1?x bulk materials have been prepared by combining fusion technique with spark plasma sintering, and their thermoelectric properties have been investigated. With the increase of Bi2Te3 content, the electrical resistivity and Seebeck coefficient increase greatly and the thermal conductivity decreases signi?cantly, which lead to a great improvement in the thermoelectric ?gure of merit ZT. The maximum ZT value reaches 1.33 at 398 K for the composition of 20% Bi2Te3–80%Sb2Te3 with 3 wt% excess Te. 相似文献
13.
Ramesh Chandra Mallik Jae-Yong Jung Soon-Chul Ur Il-Ho Kim 《Metals and Materials International》2008,14(2):223-228
In this study, indium-filled CoSb3 skutterudite is synthesized via encapsulated induction melting and subsequent annealing at 823 K for six days, and the crystal
structure, lattice constant, filler position, phase homogeneity and stability were investigated. All of the In-filled CoSb3 samples were n-type conducting samples. The temperature dependence of the electrical resistivity showed InzCo4Sb12 is a highly degenerate semiconducting material. The thermal conductivity was reduced considerably by In filling. The highest
thermoelectric figure of merit value was achieved when the In filling fraction is 0.25. It was found that the ZT of the In-filled
CoSb3 (InzCo4Sb12) was higher than that of the In-substituted CoSb3 (Co3.75In0.25Sb12 and Co4Sb11.75In0.25). This is mainly due to the lower thermal conductivity and higher Seebeck coefficient. 相似文献
14.
R.C. Mallik R. Anbalagan G. Rogl E. Royanian P. Heinrich E. Bauer P. Rogl S. Suwas 《Acta Materialia》2013,61(18):6698-6711
Skutterudites Fe0.2Co3.8Sb12?xTex (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6) were synthesized by induction melting at 1273 K, followed by annealing at 923 K for 144 h. X-ray powder diffraction and electron microprobe analysis confirmed the presence of the skutterudite phase as the main phase. The temperature-dependent transport properties were measured for all the samples from 300 to 818 K. A positive Seebeck coefficient (holes are majority carriers) was obtained in Fe0.2Co3.8Sb12 in the whole temperature range. Thermally excited carriers changed from n-type to p-type in Fe0.2Co3.8Sb11.9Te0.1 at 570 K, while in all the other samples, Fe0.2Co3.8Sb12?xTex (x = 0.2, 0.3, 0.4, 0.5, 0.6) exhibited negative Seebeck coefficients in the entire temperature range measured. Whereas for the alloys up to x = 0.2 (Fe0.2Co3.8Sb11.8Te0.2) the electrical resistivity decreased by charge compensation, it increased for x > 0.2 with an increase in Te content as a result of an increase in the electron concentration. The thermal conductivity decreased with Te substitution owing to carrier–phonon scattering and point defect scattering. The maximum dimensionless thermoelectric figure of merit, ZT = 1.04 at 818 K, was obtained with an optimized Te content for Fe0.2Co3.8Sb11.5Te0.5 and a carrier concentration of ~n = 3.0 × 1020 cm?3 at room temperature. Thermal expansion (α = 8.8 × 10?6 K?1), as measured for Fe0.2Co3.8Sb11.5Te0.5, compared well with that of undoped Co4Sb12. A further increase in the thermoelectric figure of merit up to ZT = 1.3 at 820 K was achieved for Fe0.2Co3.8Sb11.5Te0.5, applying severe plastic deformation in terms of a high-pressure torsion process. 相似文献
15.
《Intermetallics》2015
Recently, research in copper based quaternary chalcogenide materials has focused on the study of thermoelectric properties due to the complexity in the crystal structure. In the present work, stoichiometric quaternary chalcogenide compounds Cu2+xCd1−xGeSe4 (x = 0, 0.025, 0.05, 0.075, 0.1, 0.125) were prepared by solid state synthesis. The powder X-ray diffraction patterns of all the samples showed a tetragonal crystal structure with the space group I-42m of the main phase, whereas the samples with x = 0 and x = 0.025 revealed the presence of an orthorhombic phase in addition to the main phase as confirmed by Rietveld analysis. The elemental composition of all the samples characterized by Electron Probe Micro Analyzer showed a slight deviation from the nominal composition. The transport properties were measured in the temperature range of 300 K–723 K. The electrical conductivity of all the samples increased with increasing Cu content due to the enhancement of the hole concentration caused by the substitution of Cd (divalent) by Cu (monovalent). The positive Seebeck coefficient of all the samples in the entire temperature ranges indicates that holes are the majority carriers. The Seebeck coefficient of all the samples decreased with increasing Cu content and showed a reverse trend to the electrical conductivity. The total thermal conductivity of all the samples decreased with increasing temperature which was dominated by the lattice contribution. The maximum figure of merit ZT = 0.42 at 723 K was obtained for the compound Cu2.1Cd0.9GeSe4. 相似文献
16.
《Intermetallics》2017
Al2Fe3Si3, a new semiconductor with complex triclinic structure was synthesized by arc melting and spark plasma sintering, followed by heat treatment. The nominal compositions of samples have been changed to compensate Al evaporation during synthesis process, and single Al2Fe3Si3 phase has been obtained with the nominal composition of Al: Fe: Si = 26: 37: 37 (6 at.% Al excess against stoichiometry). In this study, we measured the sound velocity, thermal expansion coefficient, Vickers hardness, fracture toughness, electrical conductivity, Seebeck coefficient, and thermal conductivity of the new semiconductor Al2Fe3Si3. The Al2Fe3Si3 sample displayed positive Seebeck coefficient from 300 to 850 K, with a maximum Seebeck coefficient of 110 μV/K at 430 K. The Debye temperature of Al2Fe3Si3 was 640 K, which was similar to or higher than those of other Al, Fe, Si based thermoelectric materials, but the lattice thermal conductivity was lower, 4–5 W/mK, due to the complex crystal structure of Al2Fe3Si3. The maximum ZT value was 0.06 at 580 K. 相似文献
17.
《Intermetallics》2013
We studied the magnetostriction of Nd6Fe13−xCoxSi (x = 0, 1) intermetallic compounds with tetragonal Nd6Fe13Si-type structure, using the strain gauge method in the temperature range of 77–600 K under applied magnetic fields up to 1.5 T. The anisotropic magnetostriction (Δλ) versus temperature of the studied samples has shown almost similar field-dependence behavior. Below the spin reorientation temperature (TSR), Δλ changes its sign from positive to negative value at an applied threshold field which increases with decreasing temperature. This behavior may originate from the reduction of the magnetocrystalline anisotropy with temperature. It is also observed that absolute value of Δλ increases by Co substitution. On the other hand, the volume magnetostriction (ΔV/V) versus field shows different behavior. The ΔV/V curves of Nd6Fe12CoSi tend to have a nearly quadratic dependence on applied field near magnetic ordering temperature as expected for the parastrictive behavior. The temperature dependence of magnetostriction values is discussed based on the magnetostriction relation of the tetragonal structure to determine the signs of some of magnetostriction constants for these polycrystalline compounds. 相似文献
18.
《Intermetallics》2016
Cu1.99A0.01Se (A = Fe, Ni, Mn, In, Zn or Sm) alloys with high thermoelectric performance were prepared through a conventional melting, ball milling and quenching route, followed by a spark plasma sintering technique. Elemental doping did not change the structure type of Cu2Se. All the samples showed p-type conduction. All the doping elements except Indium reduced the electric resistivity and modified the carrier concentration, leading to a significant increase in the power factor. The lattice distortion and point defects due to the substitution of Cu became new phonon scattering centers, leading to a significant decrease in thermal conductivity. All the samples except the In-doped sample obtained better thermoelectric properties compared with the undoped Cu2Se sample. The values of the figure of merit ZT of the samples doped with Zn, Mn, Ni, Fe and Sm were 1.25, 1.28, 1.51, 1.07 and 1.07 at 823 K, respectively. In Cu2−xNixSe system, High ZT value of 1.51 is obtained for the sample of x = 0.0075 and 0.010 at 823 K. 相似文献
19.
A series of hydrochloric acid-doped polyaniline (PANI) were prepared by chemical oxidative polymerization. And the effects of HCl-doping concentration on the thermoelectric properties in the temperature range of 303–423 K were discussed. The results show that an increase in HCl-doping concentration will lead to a trend of first increase and then decrease in both the electrical conductivity and thermoelectric figure-of-merit ZT, accompanied by the opposite trend of the Seebeck coefficient. The maximum ZT can reach 2.67 × 10?4 at 423 K when HCl-doping concentration is 1.0 M. Moreover, the temperature dependence of the electrical conductivity shows a transition from non-metallic to metallic sign with doping level increasing, while the Seebeck coefficient of all the samples has a metallic character. 相似文献
20.
《Intermetallics》2014
Bulk magnetic Fe80−xCoxP13C7 (x = 0, 5, 10, 15, 20 at.%) glassy alloy rods were prepared by the combination method of fluxing treatment and J-quenching technique, and the attainable maximum diameter for fully glass formation gets to 2.5 mm for x = 5. The effects of Co substitution for Fe on the glass formation ability (GFA), thermal stability, mechanical properties and magnetic properties have been investigated systematically. It was found that the partially substitution of Co for Fe can enhance the GFA of Fe80P13C7 alloy, while excessive substitution will lead to the degradation of GFA. The compressive test shows that the substitution of Co for Fe results in the decease of fracture strength, and then significantly enhance the room temperature plastic strain of the present Fe-based BMGs, which can be identified that the plastic strain at room temperature gets to 2.5% and 3.0% for x = 5 and 10, respectively. The saturation magnetization of Fe80−xCoxP13C7 (x = 0, 5, 10, 15, 20 at.%) BMGs firstly increases from 1.477 T to 1.550 T with increasing Co content from x = 0 to 5, and then deceases from 1.549 T to 1.519 T with increasing Co content from x = 5 to 20. The Curie temperature of the present FeCoPC BMGs quickly increases with the substitution of Co for Fe. 相似文献