共查询到20条相似文献，搜索用时 15 毫秒
1.
Riley Hanus Matthias T. Agne Alexander J. E. Rettie Zhiwei Chen Gangjian Tan Duck Young Chung Mercouri G. Kanatzidis Yanzhong Pei Peter W. Voorhees G. Jeffrey Snyder 《Advanced materials (Deerfield Beach, Fla.)》2019,31(21)
The influence of micro/nanostructure on thermal conductivity is a topic of great scientific interest, particularly to thermoelectrics. The current understanding is that structural defects decrease thermal conductivity through phonon scattering where the phonon dispersion and speed of sound are assumed to remain constant. Experimental work on a PbTe model system is presented, which shows that the speed of sound linearly decreases with increased internal strain. This softening of the materials lattice completely accounts for the reduction in lattice thermal conductivity, without the introduction of additional phonon scattering mechanisms. Additionally, it is shown that a major contribution to the improvement in the thermoelectric figure of merit (zT > 2) of high‐efficiency Na‐doped PbTe can be attributed to lattice softening. While inhomogeneous internal strain fields are known to introduce phonon scattering centers, this study demonstrates that internal strain can modify phonon propagation speed as well. This presents new avenues to control lattice thermal conductivity, beyond phonon scattering. In practice, many engineering materials will exhibit both softening and scattering effects, as is shown in silicon. This work shines new light on studies of thermal conductivity in fields of energy materials, microelectronics, and nanoscale heat transfer. 相似文献
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Ki Sung Kim Young‐Min Kim Hyeona Mun Jisoo Kim Jucheol Park Albina Y. Borisevich Kyu Hyoung Lee Sung Wng Kim 《Advanced materials (Deerfield Beach, Fla.)》2017,29(36)
Structural defects often dominate the electronic‐ and thermal‐transport properties of thermoelectric (TE) materials and are thus a central ingredient for improving their performance. However, understanding the relationship between TE performance and the disordered atomic defects that are generally inherent in nanostructured alloys remains a challenge. Herein, the use of scanning transmission electron microscopy to visualize atomic defects directly is described and disordered atomic‐scale defects are demonstrated to be responsible for the enhancement of TE performance in nanostructured Ti1?x Hfx NiSn1?y Sby half‐Heusler alloys. The disordered defects at all atomic sites induce a local composition fluctuation, effectively scattering phonons and improving the power factor. It is observed that the Ni interstitial and Ti,Hf/Sn antisite defects are collectively formed, leading to significant atomic disorder that causes the additional reduction of lattice thermal conductivity. The Ti1?x Hfx NiSn1?y Sby alloys containing inherent atomic‐scale defect disorders are produced in one hour by a newly developed process of temperature‐regulated rapid solidification followed by sintering. The collective atomic‐scale defect disorder improves the zT to 1.09 ± 0.12 at 800 K for the Ti0.5Hf0.5NiSn0.98Sb0.02 alloy. These results provide a promising avenue for improving the TE performance of state‐of‐the‐art materials. 相似文献
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Qingyu Yang Chen Ming Pengfei Qiu Zhengyang Zhou Xianxiu Qiu Zhiqiang Gao Tingting Deng Lidong Chen Xun Shi 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(22):2300699
AgCuSe-based materials have attracted great attentions recently in thermoelectric (TE) field due to their extremely high electron mobility, ultralow lattice thermal conductivity, and abnormal “brittle-ductile” transition at room temperature. However, although the investigation on the crystal structure of AgCuSe low-temperature phase (named as β-AgCuSe) was started more than half a century before, it is still in controversy yet, which greatly limits the understanding of its intriguing electrical, thermal, and mechanical performance. In this work, via adopting the advanced three-dimensional electron diffraction technique, this study finds that the AgCuSe-based materials crystalize in an incommensurately modulated structure with an orthorhombic Pmmn(0β1/2)s00 superspace group. The local lattice distortion in the incommensurately modulated structure has weak effects on the conduction band minimum due to the delocalized and isotropic feature of Ag 5s states, leading to high carrier mobility. Likewise, the inhomogeneous, weak, and anisotropic Ag-Se bonds result in the high degree of anharmonicity and ultralow lattice thermal conductivity. Furthermore, alloying S in AgCuSe reinforces the interaction between the adjacent Ag-Se layers, yielding the “brittle-ductile” transition at room temperature. This work well interprets the structure–performance relationship of AgCuSe-based materials and sheds light on the future investigation of this class of promising TE materials. 相似文献
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Wen Li Linglang Zheng Binghui Ge Siqi Lin Xinyue Zhang Zhiwei Chen Yunjie Chang Yanzhong Pei 《Advanced materials (Deerfield Beach, Fla.)》2017,29(17)
Compared to commercially available p‐type PbTe thermoelectrics, SnTe has a much bigger band offset between its two valence bands and a much higher lattice thermal conductivity, both of which limit its peak thermoelectric figure of merit, zT of only 0.4. Converging its valence bands or introducing resonant states is found to enhance the electronic properties, while nanostructuring or more recently introducing interstitial defects is found to reduce the lattice thermal conductivity. Even with an integration of some of the strategies above, existing efforts do not enable a peak zT exceeding 1.4 and usually involve Cd or Hg. In this work, a combination of band convergence and interstitial defects, each of which enables a ≈150% increase in the peak zT, successfully accumulates the zT enhancements to be ≈300% (zT up to 1.6) without involving any toxic elements. This opens new possibilities for further improvements and promotes SnTe as an environment‐friendly solution for conventional p‐PbTe thermoelectrics. 相似文献
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Wenjie Liang Oded Rabin Allon I. Hochbaum Melissa Fardy Minjuan Zhang Peidong Yang 《Nano Research》2009,2(5):394-399
The thermoelectric properties of individual solution-phase synthesized p-type PbSe nanowires have been examined. The nanowires
showed near degenerately doped charge carrier concentrations. Compared to the bulk, the PbSe nanowires exhibited a similar
Seebeck coefficient and a significant reduction in thermal conductivity in the temperature range 20 K to 300 K. Thermal annealing
of the PbSe nanowires allowed their thermoelectric properties to be controllably tuned by increasing their carrier concentration
or hole mobility. After optimal annealing, single PbSe nanowires exhibited a thermoelectric figure of merit (ZT) of 0.12 at
room temperature.
相似文献
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Fengkai Guo Bo Cui Yuan Liu Xianfu Meng Jian Cao Yang Zhang Ran He Weishu Liu Haijun Wu Stephen J. Pennycook Wei Cai Jiehe Sui 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(37)
SnTe is known as an eco‐friendly analogue of PbTe without toxic elements. However, the application potentials of pure SnTe are limited because of its high hole carrier concentration derived from intrinsic Sn vacancies, which lead to a high electrical thermal conductivity and low Seebeck coefficient. In this study, Sn self‐compensation and Mn alloying could significantly improve the Seebeck coefficients in the whole temperature range through simultaneous carrier concentration optimization and band engineering, thereby leading to a large improvement of the power factors. Combining precipitates and atomic‐scale interstitials due to Mn alloying with dense dislocations induced by long time annealing, the lattice thermal conductivity is drastically reduced. As a result, an enhanced figure of merit (ZT) of 1.35 is achieved for the composition of Sn0.94Mn0.09Te at 873 K and the ZTave from 300 to 873 K is boosted to 0.78, which is of great significance for practical application. Hitherto, the ZTmax and ZTave of this work are the highest values among all single‐element‐doped SnTe systems. 相似文献
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Matthew R. Burton Tianjun Liu James McGettrick Shahin Mehraban Jenny Baker Adam Pockett Trystan Watson Oliver Fenwick Matthew J. Carnie 《Advanced materials (Deerfield Beach, Fla.)》2018,30(31)
Tin selenide (SnSe) has attracted much attention in the field of thermoelectrics since the discovery of the record figure of merit (ZT) of 2.6 ± 0.3 along the b‐axis of the material. The record ZT is attributed to an ultralow thermal conductivity that arises from anharmonicity in bonding. While it is known that nanostructuring offers the prospect of enhanced thermoelectric performance, there have been minimal studies in the literature to date of the thermoelectric performance of thin films of SnSe. In this work, preferentially orientated porous networks of thin film SnSe nanosheets are fabricated using a simple thermal evaporation method, which exhibits an unprecedentedly low thermal conductivity of 0.08 W m?1 K?1 between 375 and 450 K. In addition, the first known example of a working SnSe thermoelectric generator is presented and characterized. 相似文献
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Sergej Fust Anton Faustmann Damon J. Carrad Jochen Bissinger Bernhard Loitsch Markus Döblinger Jonathan Becker Gerhard Abstreiter Jonathan J. Finley Gregor Koblmüller 《Advanced materials (Deerfield Beach, Fla.)》2020,32(4):1905458
Nanowires (NWs) hold great potential in advanced thermoelectrics due to their reduced dimensions and low-dimensional electronic character. However, unfavorable links between electrical and thermal conductivity in state-of-the-art unpassivated NWs have, so far, prevented the full exploitation of their distinct advantages. A promising model system for a surface-passivated one-dimensional (1D)-quantum confined NW thermoelectric is developed that enables simultaneously the observation of enhanced thermopower via quantum oscillations in the thermoelectric transport and a strong reduction in thermal conductivity induced by the core–shell heterostructure. High-mobility modulation-doped GaAs/AlGaAs core–shell NWs with thin (sub-40 nm) GaAs NW core channel are employed, where the electrical and thermoelectric transport is characterized on the same exact 1D-channel. 1D-sub-band transport at low temperature is verified by a discrete stepwise increase in the conductance, which coincided with strong oscillations in the corresponding Seebeck voltage that decay with increasing sub-band number. Peak Seebeck coefficients as high as ≈65–85 µV K−1 are observed for the lowest sub-bands, resulting in equivalent thermopower of S2σ ≈ 60 µW m−1 K−2 and S2G ≈ 0.06 pW K−2 within a single sub-band. Remarkably, these core–shell NW heterostructures also exhibit thermal conductivities as low as ≈3 W m−1 K−1, about one order of magnitude lower than state-of-the-art unpassivated GaAs NWs. 相似文献
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Chang Nie Chong Wang Yongjie Xu Yuxin Liu Xiaojian Niu Shuang Li Yaru Gong Yunxiang Hou Xuemei Zhang Dewei Zhang Di Li Yongsheng Zhang Guodong Tang 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(28):2301298
SnTe, emerging as an environment-friendly alternative to conventional PbTe thermoelectrics, has drawn significant attention for clean energy conversion. Here, a high peak figure of merit (ZT) of 1.45 at 873 K in Ge/Bi codoped SnTe–AgBiTe2 alloys is reported. It is demonstrated that the existence of Ge, Bi, and Ag facilitate band convergence in SnTe, resulting in remarkable enhancement of Seebeck coefficient and power factor. Simultaneously, localized lattice imperfections including dislocations, point defects, and micro/nanopore structures are caused by incorporation of Ge, Bi, and Ag, which can effectively scatter heat carrying phonons with different wavelengths and contribute to an extremely low κL of 0.61 W m−1 K−1 in Sn0.92Ge0.04Bi0.04Te–10%AgBiTe2. Such high peak ZT is achieved by decouples electron and phonon transport through band modification and localized lattice engineering, highlighting promising solutions for advancing thermoelectrics. 相似文献
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采用真空熔炼、机械球磨及放电等离子烧结技术(SPS)制备得到了(Ag2Te)x(Bi0.5Sb1.5Te3)1-x(x=0,0.025,0.05,0.1)系列样品,性能测试表明,Ag2Te的掺入可以显著改变材料的热电性能变化趋势,掺杂样品在温度为450~550K范围内具有较未掺杂样品更优的热电性能.适当量的Ag2Te掺入能够有效地提高材料的声子散射,降低材料的热导率.在测试温度范围内,(Ag2Te)0.05(Bi0.5Sb1.5Te3)0.95具有最低的晶格热导,室温至575K范围内保持在0.2~0.3W/(m·K)之间,在575K时,(Ag2Te)0.05(Bi0.5Sb1.5Te3)0.95试样具有最大热电优值ZT=0.84,相较于未掺杂样品提高了约20%. 相似文献
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Vaishali Taneja;Subarna Das;Kapildeb Dolui;Tanmoy Ghosh;Animesh Bhui;Usha Bhat;Dinesh Kumar Kedia;Koushik Pal;Ranjan Datta;Kanishka Biswas; 《Advanced materials (Deerfield Beach, Fla.)》2024,36(6):2307058
Achieving glass-like ultra-low thermal conductivity in crystalline solids with high electrical conductivity, a crucial requirement for high-performance thermoelectrics , continues to be a formidable challenge. A careful balance between electrical and thermal transport is essential for optimizing the thermoelectric performance. Despite this inherent trade-off, the experimental realization of an ideal thermoelectric material with a phonon-glass electron-crystal (PGEC) nature has rarely been achieved. Here, PGEC-like AgSbTe2 is demonstrated by tuning the atomic disorder upon Yb doping, which results in an outstanding thermoelectric performance with figure of merit, zT ≈ 2.4 at 573 K. Yb-doping-induced enhanced atomic ordering decreases the overlap between the hole and phonon mean free paths and consequently leads to a PGEC-like transport behavior in AgSbTe2. A twofold increase in electrical mobility is observed while keeping the position of the Fermi level (EF) nearly unchanged and corroborates the enhanced crystalline nature of the AgSbTe2 lattice upon Yb doping for electrical transport. The cation-ordered domains, lead to the formation of nanoscale superstructures (≈2 to 4 nm) that strongly scatter heat-carrying phonons, resulting in a temperature-independent glass-like thermal conductivity. The strategy paves the way for realizing high thermoelectric performance in various disordered crystals by making them amorphous to phonons while favoring crystal-like electrical transport. 相似文献
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利用计算机生成不同的AlN/橡胶复合材料等效结构单元,基于三维格子玻尔兹曼模型计算了复合材料的等效热导率。实验制备了AlN/橡胶复合材料,并测定了不同填充量下复合材料的热导率,用以验证模型的有效性。将LBM计算结果与实验结果及Maxwell、Bruggeman、Nielsen等模型进行了比较,发现本文数值计算结果与Maxwell模型吻合较好,相比较于Bruggeman模型与Nielsen模型更加接近实验值。研究了AlN颗粒尺寸及分布方式对复合材料导热性能的影响。结果表明,一定体积分数范围内,粒径较小的AlN颗粒填充橡胶复合材料的等效热导率较大,当体积分数增大到20%,粒径较大的复合材料内先开始形成导热网络,大大提高了热导率;随机分布比均匀分布方式下的复合材料的等效热导率大,不同的粒子空间分布结构是影响复合材料热导率的关键因素。 相似文献
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Matteo Cagnoni Daniel Führen Matthias Wuttig 《Advanced materials (Deerfield Beach, Fla.)》2018,30(33)
Thermoelectric materials provide a challenge for materials design, since they require optimization of apparently conflicting properties. The resulting complexity has favored trial‐and‐error approaches over the development of simple and predictive design rules. In this work, the thermoelectric performance of IV–VI chalcogenides on the tie line between GeSe and GeTe is investigated. From a combination of optical reflectivity and electrical transport measurements, it is experimentally proved that the outstanding performance of IV–VI compounds with octahedral‐like coordination is due to the anisotropy of the effective mass tensor of the relevant charge carriers. Such an anisotropy enables the simultaneous realization of high Seebeck coefficients, due to a large density‐of‐states effective mass, and high electrical conductivity, caused by a small conductivity effective mass. This behavior is associated to a unique bonding mechanism by means of a tight‐binding model, which relates band structure and bond energies; tuning the latter enables tailoring of the effective mass tensor. The model thus provides atomistic design rules for thermoelectric chalcogenides. 相似文献
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Shuling WANG;Meng JIANG;Lianjun WANG;Wan JIANG 《无机材料学报》2023,38(7):807-814
n-Type AgBiSe2-based compounds are considered as promising high-performance thermoelectric (TE) materials due to the low lattice thermal conductivity. However, their two phase transitions between 300 and 700 K limits their applications. Therefore, it is crucial to obtain AgBiSe2-based compounds with stable structures and optimized TE properties. In this work, the Pb-free group IV-VI compound SnTe is selected for alloying with AgBiSe2. Introduction of SnTe not only reduces the cubic phase transition temperature, but also effectively suppresses the reversible phase transition of AgBiSe2. At room temperature, reduction of the lattice thermal conductivity from 0.76 to 0.51 W·m-1·K-1 results from highly disordered distribution of atoms. Furthermore, Nb dopant to replace Ag, significantly improves carrier concentration of AgBiSe2-based compounds, which promotes the effective mass and increases the electrical conductivity from 77.7 S·cm-1 to 158.1 S·cm-1 at room temperature. Meanwhile, the defect scattering at high temperature is enhanced with the increase of impurity point defects, leading to the lattice thermal conductivity reduced. At 700 K, the lattice thermal conductivity is reduced from 0.56 to 0.43 W·m-1·K-1, obtaining stable cubic phase compound (Ag0.98Nb0.02BiSe2)0.75(SnTe)0.25 with a ZT of 0.32 at 650 K. These results indicate that the (AgBiSe2)0.75(SnTe)0.25 compound is a promising n-type TE compound with low lattice thermal conductivity and a stable cubic structure. Such efforts provide a scheme for the crystal structure regulation of high-performance TE materials with phase transition and promotion of its application. 相似文献
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Chaochao Dun Corey A. Hewitt Qi Li Junwei Xu Drew C. Schall Hyunsu Lee Qike Jiang David. L. Carroll 《Advanced materials (Deerfield Beach, Fla.)》2017,29(21)
Engineered atomic dislocations have been used to create a novel, Sb2Te3 nanoplate‐like architecture that exhibits a unique antisymmetric chirality. High‐resolution transmission electron microscopy (HRTEM) coupled with atomic force microscopy and X‐ray photoelectron spectroscopy reveals the architectures to be extremely well ordered with little residual strain. Surface modification of these topologically complex macrostructures (≈3 µm) has been achieved by direct growth of metallic Ag nanoparticles onto the edge sites of the Sb2Te3. Again, HRTEM shows this nanoparticle decoration to be atomically sharp at the boundaries and regularly spaced along the selvedge of the nanostructure. Transport experiments of densified films of these assemblies exhibit marked increases in carrier density after nanoengineering, yielding 3.5 × 104 S m?1 in electrical conductivity. An increased Seebeck coefficient by 20% in parallel with electrical conductivity is also observed. This gives a thermoelectric power factor of 371 µW m?1 K?2, which is the highest value for a flexible, freestanding film to date. These results suggest an entirely new direction in the search for wearable power harvesters based on topologically complex, low‐dimensional nanoassemblies. 相似文献