共查询到20条相似文献,搜索用时 31 毫秒
1.
M. T. Barako W. Park A. M. Marconnet M. Asheghi K. E. Goodson 《Journal of Electronic Materials》2013,42(3):372-381
Thermoelectric modules experience performance reduction and mechanical failure due to thermomechanical stresses induced by thermal cycling. The present study subjects a thermoelectric module to thermal cycling and evaluates the evolution of its thermoelectric performance through measurements of the thermoelectric figure of merit, ZT, and its individual components. The Seebeck coefficient and thermal conductivity are measured using steady-state infrared microscopy, and the electrical conductivity and ZT are evaluated using the Harman technique. These properties are tracked over many cycles until device failure after 45,000 thermal cycles. The mechanical failure of the TE module is analyzed using high-resolution infrared microscopy and scanning electron microscopy. A reduction in electrical conductivity is the primary mechanism of performance reduction and is likely associated with defects observed during cycling. The effective figure of merit is reduced by 20% through 40,000 cycles and drops by 97% at 45,000 cycles. These results quantify the effect of thermal cycling on a commercial TE module and provide insight into the packaging of a complete TE module for reliable operation. 相似文献
2.
3.
In quasi-one-dimensional organic crystals, the relaxation time as a function of carrier energy can exhibit, under certain conditions, a rather high and sharp maximum. It is shown that this maximum and its position on the energy scale influence the electrical conductivity and electronic thermal conductivity in different ways. First, the electrical conductivity is considerably increased. The electronic thermal conductivity is also increased, but to a lesser extent due to the narrower energy interval of carriers that contribute to energy transport. Second, both the electrical conductivity and electronic thermal conductivity achieve maximums, but the latter is displaced to higher carrier concentrations in comparison with the maximum of electrical conductivity. As a consequence, the Lorenz number is decreased for some range of carrier concentration and is increased in other ranges. It is important that there is a large interval of carrier concentrations where the Lorenz number is significantly diminished, and the Fermi level can be moved up to this interval. The Lorenz number may be diminished considerably in comparison with ordinary materials. This is favorable for increase of the thermoelectric figure of merit. 相似文献
4.
L. P. Bulat V. B. Osvenskii A. A. Ivanov A. I. Sorokin D. A. Pshenay-Severin V. T. Bublik N. Yu. Tabachkova V. P. Panchenko M. G. Lavrentev 《Semiconductors》2017,51(7):854-857
The temperature dependences of the specific heat, thermal conductivity, coefficient of thermal expansion (CTE), and transport coefficients (electrical conductivity and thermoelectric power) of copper selenide are experimentally and theoretically investigated in the temperature range of 300–873 K. The calculation results correlate with the experimental data up to a temperature of ~773 K. The maximum thermoelectric figure of merit of nanostructured copper selenide is ZT ~ 1.8. The correlation dependence between ZT and the thermal conductivity within the entire temperature range under consideration is shown. 相似文献
5.
Domenic Prete Elisabetta Dimaggio Valeria Demontis Valentina Zannier Maria Jesus Rodriguez-Douton Lorenzo Guazzelli Fabio Beltram Lucia Sorba Giovanni Pennelli Francesco Rossella 《Advanced functional materials》2021,31(37):2104175
Semiconductor nanostructures have raised much hope for the implementation of high-performance thermoelectric generators. Indeed, they are expected to make available reduced thermal conductivity without a heavy trade-off on electrical conductivity, a key requirement to optimize the thermoelectric figure of merit. Here, a novel nanodevice architecture is presented in which ionic liquids are employed as thermally-insulating gate dielectrics. These devices allow the field-effect control of electrical transport in suspended semiconducting nanowires in which thermal conductivity can be simultaneously measured using an all-electrical setup. The resulting experimental data on electrical and thermal transport properties taken on individual nanodevices can be combined to extract ZT, guide device optimization and dynamical tuning of the thermoelectric properties. 相似文献
6.
Bin Su Zhanran Han Yilin Jiang Hua-Lu Zhuang Jincheng Yu Jun Pei Haihua Hu Jing-Wei Li Yu-Xiao He Bo-Ping Zhang Jing-Feng Li 《Advanced functional materials》2023,33(37):2301971
Thermoelectric technology enables the direct interconversion between heat and electricity. SnSe has received increasing interest as a new promising thermoelectric compound due to its exceptionally high performance reported in crystals. SnSe possesses intrinsic low thermal conductivity as a congenital advantage for thermoelectric, but high thermoelectric performance can be hardly achieved due to the difficulty to realize efficient doping to raise its low carrier concentration to an optimal level. In this work, it is found that a series of rare earth elements are effective dopants for SnSe, which can greatly improve the electrical transport properties of p-type polycrystalline SnSe. In particular, the remarkable enhancement in electrical conductivity and power factor is achieved by Na/Er co-doping at 873 K. The lattice thermal conductivity is reduced due to the presence of abundant defects (dislocations, stacking faults, and twin boundaries). Consequently, a peak thermoelectric figure of merit ZT (2.1) as well as a high average ZT (0.77) are achieved in polycrystalline SnSe. 相似文献
7.
Takashi Komine Masahiro Kuraishi Takayuki Teramoto Ryuji Sugita Yasuhiro Hasegawa Masayuki Murata Daiki Nakamura 《Journal of Electronic Materials》2010,39(9):1606-1610
We have used the finite-element method to calculate numerically the equations of electrical and thermal transport. The thermal
conductivity of a wire array is analyzed. The influence of the wire array on the effective thermal conductivity of the element
is discussed. The effective thermal conductivity decreases as the wire diameter is reduced. Decreasing the packing density
significantly reduces the effective thermal conductivity. In the classical regime, the ratio of the effective electrical conductivity
to the effective thermal conductivity of the wire array can be expressed as a function of packing density; this ratio decreases
as the packing density decreases. The ratio for a wire array with realistic parameters is similar to that of bulk bismuth.
Therefore, to improve the thermoelectric figure of merit, it is critical to enhance the intrinsic power factor in a wire by
exploiting thermomagnetic or quantum effects. 相似文献
8.
Ytterbium trialuminide (YbAl3) has one of the largest thermoelectric power factors of known materials below room temperature, making it a material of interest for low-temperature thermoelectric devices. However, the high thermal conductivity, which is due to a combination of a large electronic thermal conductivity and a moderately large lattice thermal conductivity, is detrimental to the figure of merit. Substitution of different atoms on the Yb site was performed in order to assess their ability to favorably alter the electronic structure and/or reduce the lattice thermal conductivity. We have synthesized and studied the thermoelectric properties of the solid solutions of YbAl3 with ErAl3 and LuAl3. Results for electrical conductivity, thermal conductivity, and Seebeck coefficient for several of these solid solutions over the temperature range of 80 K to 300 K are reported. Although most substituted samples are driven toward a metallic state, we find that for some compositions the figure of merit is enhanced relative to pure YbAl3. 相似文献
9.
Xun Shi Jiong Yang Shengqiang Bai Jihui Yang Hsin Wang Miaofang Chi James R. Salvador Wenqing Zhang Lidong Chen Winnie Wong‐Ng 《Advanced functional materials》2010,20(5):755-763
Type I clathrates have recently been identified as prospective thermoelectric materials for power generation purposes due to their very low lattice thermal conductivity values. The maximum thermoelectric figure of merit of almost all type I clathrates is, however, less than 1 and occurs at, or above, 1000 K, making them unfavorable especially for intermediate temperature applications. In this report, the Zintl–Klemm rule is demonstrated to be valid for Ni, Cu, and Zn transition metal substitution in the framework of type I clathrates and offers many degrees of freedom for material modification, design, and optimization. The cross‐substitution of framework elements introduces ionized impurities and lattice defects into these materials, which optimize the scattering of charge carriers by the substitution‐induced ionized impurities and the scattering of heat‐carrying lattice phonons by point defects, respectively, leading to an enhanced power factor, reduced lattice thermal conductivity, and therefore improved thermoelectric figure of merit. Most importantly, the bandgap of these materials can be tuned between 0.1 and 0.5 eV by adjusting the cross‐substitution ratio of framework elements, making it possible to design clathrates with excellent thermoelectric properties between 500 and 1000 K. 相似文献
10.
Fangfang Kong Congcong Liu Jingkun Xu Yao Huang Jianmin Wang Zhi Sun 《Journal of Electronic Materials》2012,41(9):2431-2438
Significant enhancement of thermoelectric (TE) performance was observed for free-standing poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT: PSS) composite films obtained from a PEDOT:PSS aqueous solution by simultaneous addition of dimethyl sulfoxide (DMSO) and different concentrations of urea. The electrical conductivity was enhanced from 8.16?S?cm?1 to over 400?S?cm?1, and the maximum Seebeck coefficient reached a value of 18.81???V?K?1 at room temperature. The power factor of the PEDOT:PSS composite films reached 8.81???W?m?1?K?2. The highest thermoelectric figure of merit (ZT) in this study was 0.024 at room temperature, which is at least one order of magnitude higher than most polymers and bulk Si. These results indicate that the obtained composite films are a promising thermoelectric material for applications in thermoelectric refrigeration and thermoelectric microgeneration. 相似文献
11.
Hanfu Wang Weiguo Chu Dongwei Wang Weichen Mao Wenzhi Pan Yanjun Guo Yufeng Xiong Hao Jin 《Journal of Electronic Materials》2011,40(5):624-628
β-Ag2Se is a narrow-bandgap semiconductor with a high electrical conductivity, reasonably large Seebeck coefficient, and low thermal
conductivity. It is regarded as a potential candidate for thermoelectric applications. In this work, we prepared powders of
β-Ag2Se by hydrothermal reaction at 180°C. The spark plasma sintering technique was employed to form compact samples. The thermoelectric
properties were measured in a temperature range between 20 K and 350 K. A maximum figure of merit of over 0.6 was found around
room temperature. Theoretical calculations were carried out to estimate the Seebeck coefficient of β-Ag2Se, reproducing the experimental trend qualitatively. 相似文献
12.
一种测试半导体制冷器的瞬态方法 总被引:1,自引:0,他引:1
ZT值、最大制冷温差和响应时间是表征半导体制冷器性能的重要参数.文中介绍了一种能同时测量这三个参数的瞬态方法,并讨论了热沉对测试结果的影响.利用一个由恒流脉冲发生器和数据采集卡组成的简单测试系统测得制冷器在小电流下的电阻电压和塞贝克电压,通过这两个电压推导出ZT值、最大制冷温差.这种瞬态方法是非接触式测量,准确度高,可用于薄膜热电器件测试;另外瞬态方法耗时短,可大大缩短半导体制冷器可靠性测试的周期.采用这种方法对4mm×4mm×2.4mm的热电制冷器进行实验,环境温度300K时,测得ZT值为0.39,最大温差58.5K,响应时间20s. 相似文献
13.
ZT值、最大制冷温差和响应时间是表征半导体制冷器性能的重要参数.文中介绍了一种能同时测量这三个参数的瞬态方法,并讨论了热沉对测试结果的影响.利用一个由恒流脉冲发生器和数据采集卡组成的简单测试系统测得制冷器在小电流下的电阻电压和塞贝克电压,通过这两个电压推导出ZT值、最大制冷温差.这种瞬态方法是非接触式测量,准确度高,可用于薄膜热电器件测试;另外瞬态方法耗时短,可大大缩短半导体制冷器可靠性测试的周期.采用这种方法对4mm×4mm×2.4mm的热电制冷器进行实验,环境温度300K时,测得ZT值为0.39,最大温差58.5K,响应时间20s. 相似文献
14.
Type I clathrate bulk materials Ba8Sb2Ga14Ge30 were prepared by the melt spinning (MS) technique combined with the spark plasma sintering (SPS) method. The microstructure
and thermoelectric transport properties of the compounds were investigated. The results show that the grain size decreases
greatly compared with materials obtained by the traditional melting and SPS method. The electrical conductivity increases
greatly and the lattice thermal conductivity decreases significantly with increasing roller linear speed. The maximum thermoelectric
dimensionless figure of merit ZT of 1.05 is obtained at 950 K for the sample prepared by melt spinning with a roller linear speed of 40 m/s. 相似文献
15.
Recently, nanostructuring of bulk semiconductors has emerged as an effective approach to develop high-efficiency thermoelectric
materials for large-scale device applications, where the thermal conductivity reduction predominates in the enhanced figure
of merit of these materials. In this work, a quantitative nanothermodynamic model was established to calculate the lattice
thermal conductivity of semiconductor nanocomposites considering the interface scattering effects. It is found that the lattice
thermal conductivity can be significantly reduced in nanostructured bulk semiconductors compared with their bulk counterparts.
The findings in this work may provide new insights into the fundamental understanding of phonon transport in nanocomposites
and also the development of high-performance thermoelectric materials. 相似文献
16.
Exhaustive attempts are made in recent decades to improve the performance of thermoelectric materials that are utilized for waste heat‐to‐electricity conversion. Energy filtering of charge carriers is directed toward enhancing the material thermopower. This paper focuses on the theoretical concepts, experimental evidence, and the authors' view of energy filtering in the context of thermoelectric materials. Recent studies suggest that not all materials experience this effect with the same intensity. Although this effect theoretically demonstrates improvement of the thermopower, applying it poses certain constraints, which demands further research. Predicated on data documented in literature, the unusual dependence of the thermopower and conductivity upon charge carrier concentrations can be altered through the energy filtering approach. Upon surmounting the physical constraints discussed in this article, thermoelectric materials research may gain a new direction to enhance the power factor and thermoelectric figure of merit. 相似文献
17.
Engineering Thermal Conductivity for Balancing Between Reliability and Performance of Bulk Thermoelectric Generators
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Hee Seok Kim Tianbao Wang Weishu Liu Zhifeng Ren 《Advanced functional materials》2016,26(21):3678-3686
The nanostructuring approach has significantly contributed to the improving of thermoelectric figure‐of‐merit (ZT) by reducing lattice thermal conductivity. Even though it is an effective method to enhance ZT, the drastically lowered thermal conductivity in some cases can cause thermomechanical issues leading to decreased reliability of thermoelectric generators. Here, an engineering thermal conductivity (κeng) is defined as a minimum allowable thermal conductivity of a thermoelectric material in a module, and is evaluated to avoid thermomechanical failure and thermoelectric degradation of a device. Additionally, there is dilemma of determining thermoelectric leg length: a shorter leg is desired for higher W kg?1, W cm?3, and W The nanostructuring approach has significantly contributed to the improving of thermoelectric figure‐of‐merit (ZT) by reducing lattice thermal conductivity. Even though it is an effective method to enhance ZT, the drastically lowered thermal conductivity in some cases can cause thermomechanical issues leading to decreased reliability of thermoelectric generators. Here, an engineering thermal conductivity (κeng) is defined as a minimum allowable thermal conductivity of a thermoelectric material in a module, and is evaluated to avoid thermomechanical failure and thermoelectric degradation of a device. Additionally, there is dilemma of determining thermoelectric leg length: a shorter leg is desired for higher W kg?1, W cm?3, and W $?1, but it raises the thermomechanical vulnerability issue. By considering a balance between the thermoelectric performance and thermomechanical reliability issues, it is discussed how to improve device reliability of thermoelectric generators and the engineering thermal conductivity of thermoelectric materials. 相似文献
18.
Gaosheng Fu Lei Zuo Jon Longtin Chao Nie Yikai Chen Mahder Tewolde Sanjay Sampath 《Journal of Electronic Materials》2014,43(7):2723-2730
The thermoelectric properties of magnesium silicide (Mg2Si) samples prepared by use of an atmospheric plasma spray (APS) were compared with those of samples prepared from the same feedstock powder by use of the conventional hot-pressing method. The characterization performed included measurement of thermal conductivity, electrical conductivity, Seebeck coefficient, and figure of merit, ZT. X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive x-ray spectroscopy (EDX) were used to assess how phase and microstructure affected the thermoelectric properties of the samples. Hall effect measurements furnished carrier concentration, and measurement of Hall mobility provided further insight into electrical conductivity and Seebeck coefficient. Low temperature and high velocity APS using an internal-powder distribution system achieved a phase of composition similar to that of the feedstock powder. Thermal spraying was demonstrated in this work to be an effective means of reducing the thermal conductivity of Mg2Si; this may be because of pores and cracks in the sprayed sample. Vacuum-annealed APS samples were found to have very high Seebeck coefficients. To further improve the figure of merit, carrier concentration must be adjusted and carrier mobility must be enhanced. 相似文献
19.
Hirokazu Takaki Kazuaki Kobayashi Masato Shimono Nobuhiko Kobayashi Kenji Hirose 《Journal of Electronic Materials》2017,46(10):5593-5598
The thermoelectric properties of TiN/MgO surface nanostructures have been determined using first-principles calculations based on the nonequilibrium Green’s function (NEGF) method. Through structural modification of the surfaces at the atomistic level, we find that the metallic TiN thin-film layer becomes semiconducting with a small bandgap, which enhances the Seebeck coefficient, while the electrical conductivity remains high at room temperature. Hence, a much larger thermoelectric figure of merit is obtained compared with bulk. These findings indicate the possibility of designing thermoelectric devices with surface nanostructures. 相似文献
20.
On Intensifying Carrier Impurity Scattering to Enhance Thermoelectric Performance in Cr‐Doped CeyCo4Sb12
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Shanyu Wang Jiong Yang Lihua Wu Ping Wei Wenqing Zhang Jihui Yang 《Advanced functional materials》2015,25(42):6660-6670
The beneficial effect of impurity scattering on thermoelectric properties has long been disregarded even though possible improvements in power factor have been suggested by Ioffe more than a half century ago. Here it is theoretically and experimentally demonstrated that proper intensification of ionized impurity scattering to charge carriers can benefit the thermoelectric figure of merit (ZT) by increasing the Seebeck coefficient and decreasing the electronic thermal conductivity. The optimal strength of ionized impurity scattering for maximum ZT depends on the Fermi level and the density of states effective mass. Cr‐doping in CeyCo4Sb12 progressively increases the strength of ionized impurity scattering, and significantly improves the Seebeck coefficient, resulting in high power factors of 45 μW cm?1 K?2 with relatively low electrical conductivity. This effect, combined with the increased Ce‐filling fraction and thus decreased lattice thermal conductivity by charge compensation of Cr‐dopant, gives rise to a maximum ZT of 1.3 at 800 K and a large average ZT of 1.1 between 500 and 850 K, ≈30% and ≈20% enhancements as compared with those of Cr‐free sample, respectively. Furthermore, this study also reveals that carrier scattering parameter can be another fundamental degree of freedom to optimize electrical properties and improve thermal‐to‐electricity conversion efficiencies of thermoelectric materials. 相似文献