热电材料塞贝克系数的测量研究

热电材料是一类可以将热能和电能直接相互转化的新型能源材料,已广泛应用于温差发电和制冷领域,塞贝克系数是评价热电材料性能的重要参数,其准确测量尤为关键。总结了塞贝克系数的测量误差和准确测量的影响因素,并验证了建立的测量方法的准确性。     

基于热电模块实验的低温下塞贝克系数的测量

利用热电发电器（TEG）进行温差发电是LNG冷能利用的方式之一,而目前低温下热电材料塞贝克系数（α）研究的缺失给低温TEG的设计带来了障碍。因此,本文提出一种通过TEG模块的实验得到低温下该模块所用热电材料α的测量方法,并测试了热电材料Bi2Te3在90~180 K温度范围内的α。结果表明：Bi2Te3在低温下的α随温度的降低而减小,温度从180 K降至90 K,塞贝克系数从124.6 μV/K降至49.3 μV/K,且与温度成二次函数关系。     

中国计量院成功研制材料逆反射系数测量装置

本刊讯 近日,由中国计量科学研究院自主研制的逆反射系数测量装置通过了专家验收。该装置成功实现了我国材料逆反射系数的高准确度测量和校准．测量结果不确定度达3．6％（k=2）：装置采用光强标准灯组对测量系统进行量值溯源．研究并实现了逆反射系数的照度测量方法     

稀土元素Tm掺杂对Cu2S热电性能影响研究

Cu₂S具有较低的晶格热导率和窄禁带宽度,它热电性能优异、成本低廉且无毒等优点引起了热电材料相关研究领域的广泛关注。采用水热合成法与真空烧结法相结合的方式制备Cu₂S基热电材料,通过物相、成分表征和热电性能测试等手段,研究稀土元素Tm掺杂对Cu₂S基材料热电性能的影响规律,并采用第一性原理开展掺杂后Cu₂S能带结构和态密度计算。研究结果表明,水热合成法可以获得Cu₃₁S₁₆粉体,在真空烧结过程中物相发生了转变,从原来的Cu₃₁S₁₆转变为Cu₂S。掺杂Tm元素可显著提高Cu₂S粉体的结晶性能,随着掺杂含量的增加,Cu₂S团聚现象逐渐消失。Cu₂S塞贝克系数随Tm掺杂量的增加有所提升,其中掺杂2%Tm的Cu₂S在350℃处于相变温度,塞贝克系数达到峰值1589.71μV/K;随掺杂元素的增加和温度的升高,C...     

Sb/Al/Zn多掺杂Mg2Si热电材料的制备及性能研究

采用放电等离子体烧结技术,制备了Sb/Al/Zn多掺杂Mg_2Si热电材料,利用粉末X射线衍射、霍尔效应和标准四探针电导率研究了Mg_2Si热电材料的电输运特性和热电性能。结果表明,Sb/Al/Zn多掺杂Mg_2Si热电材料具有良好的电输运和热电性能。采用放电等离子体烧结技术在880 K时,Sb0.5%Zn0.5%掺杂Mg_2Si热电材料具有最大热电优值为0.964,与PbTe基热电材料相当。根据电导率(σ)、塞贝克系数(S)和热导率(κ)的温度依赖性计算掺杂Mg_2Si热电材料在300～900 K的热电性能和热电图优值(ZT),同时根据霍尔系数确定掺杂Mg_2Si热电材料的电子浓度(N)。     

N型Bi2Te2.7-zSzSe0.3热电材料的微观组织与热电性能

通过真空熔炼、快速凝固、球磨制粉、冷压成形和常压烧结工艺,制备了Bi₂Te_2.7-zS_zSe_0.3热电材料,表征了Bi₂Te_2.7-zS_zSe_0.3热电材料晶体结构、微观形貌、塞贝克系数、热导率、热电优值和功率因子等热电性能。研究了掺杂S的Bi₂Te_2.7-zS_zSe_0.3热电材料热电性能与机理。结果表明,Bi₂Te_2.7-zS_zSe_0.3热电材料晶体结构为R-3m空间群斜方晶系的六面体层状结构;掺杂S的Bi₂Te_2.7-zS_zSe_0.3热电材料,生成较Bi-Te化学键强的Bi-S,V¨Te空位形成能E_v(Bi-Te)降低,Bi′<...     

水热法合成Ag_2S/Bi_2S_3复合材料及其热电性能研究

采用水热合成法结合放电等离子烧结技术制备了Ag_2S/Bi_2S_3块体热电复合材料。采用XRD、SEM和TEM对合成粉末材料的相组成和微观形貌进行分析,闪光法和塞贝克系数/电阻测量系统测试复合块材的热电性能,系统地研究了Ag_2S的含量对Ag_2S/Bi_2S_3复合材料热电性能的影响。实验结果表明,水热法成功地合成了具有球形结构的Ag_2S/Bi_2S_3复合粉末;块体样品的塞贝克系数都为负,说明样品为n型半导体;适量的Ag_2S复合Bi_2S_3不仅有效地降低了材料的热导率,同时也提高了电导率;当Bi_2S_3与3%的Ag_2S复合时样品的热电优值(ZT值)最大,其在724K时的ZT值为0.23,为纯Bi_2S_3样品在该温度ZT值的2.3倍。     

多掺杂协同调控碲化锡热导率和功率因子提升热电性能

碲化锡(SnTe)是一种碲化铅的无铅替代物, 在热电领域有广阔的应用前景。但是, 纯相碲化锡样品具有较高的热导率与较低的塞贝克系数, 导致热电性能较差。本研究通过多重掺杂可以显著降低热导率, 提升塞贝克系数, 从而提升热电性能。SnTe热压样品的晶格热导率随着Se和S的引入明显降低,比如SnTe_0.7S_0.15Se_0.15室温下晶格热导率仅为0.99 W•m^-1•K^-1。透射电子显微镜显示, SnTe掺杂样品内存在大量的纳米沉淀相与晶格位错。在此基础上, 掺杂In在价带顶引入共振态大幅提高了样品的塞贝克系数。实验表明通过多重掺杂可以有效提升碲化锡的热电性能, 其中样品Sn_0.99In_0.01Te_0.7S_0.15Se_0.15在850 K时峰值ZT值达到0.8, 这说明碲化锡的确是一种有应用前景的中温区热电材料。     

质量比较仪的衡量模式分析

质量比较仪广泛应用于高准确度砝码的测量,作为质量量值传递的重要衡量仪器,对其测量方法的分析有利于保障质量量值传递溯源的准确可靠。研究其测量方法与砝码量值传递的衡量模式的差异,即使用等量的不同标准砝码与同一砝码的两种模式,进行试验,并分析了其测量结果与不确定度。     

热电材料塞贝克系数测试仪研制

为避免热电材料在高温测试过程中被氧化,基于塞贝克效应(Seebeck effect)设计一种在真空高温环境下测试热电材料Seebeck系数的新型装置。装置主要包括真空系统、样品支架系统和控制总成3部分。该新型装置成本低廉,易于操作,其应用不但可以有效防止高温环境中样品测试的氧化现象,而且可以在高温真空环境下准确、快速地测量样品的Seebeck系数。     

Traceable Thermoelectric Measurements of Seebeck Coefficients in the Temperature Range from 300 K to 900 K

This work is focused on the characterization of thermoelectric reference materials with traceable Seebeck coefficients in the temperature range from 300 K to 900 K. The presented measurement system will provide a relative uncertainty of the measurement of the Seebeck coefficient of about 5 %. The Seebeck coefficient represents an important component of the figure of merit ZT and thus the low uncertainty of the Seebeck coefficient will also lower the uncertainty of the ZT value. We also present data which lead to the launch of the certification process of a NiCu-alloy according to the ISO Guide 35.     

Traceable Measurements of Seebeck Coefficients of Thermoelectric Materials by Using Noble Metal Thermocouples

The characterization of thermoelectric materials as reference materials for Seebeck coefficients at the Physikalisch-Technische Bundesanstalt (PTB) is based on the usage of gold/platinum differential thermocouples. In the case of thermoelectric materials containing silicon, the gold/platinum thermocouples are insufficient due to reactions with the silicon when the samples are at higher temperatures. To overcome this limitation and to expand the temperature range for the certification process, platinum/palladium thermocouples were incorporated in the measurement setup. This paper discusses the influence of the different differential thermocouples used for the measurement of the Seebeck coefficients. Results of a comparative investigation of Seebeck coefficient measurements of a metallic and two semiconducting reference materials in the temperature range from 300 K to 870 K are presented.     

聚噻吩及其衍生物热电材料研究进展

近来,聚合物热电材料因其成本低、资源丰富、热导率低等优势被认为是最有前途的热电材料之一。聚噻吩及其衍生物是研究较为广泛的一类聚合物热电材料。综述了近年来聚噻吩、聚噻吩衍生物以及聚噻吩基/无机复合热电材料在热电领域的研究进展。已有研究表明,聚噻吩及其衍生物热电材料具有高的Seebeck系数,其See-beck系数与电导率通常是此消彼长的关系。通过制备低维材料,与高电导率的无机纳米材料复合以及适度掺杂等方法可有效提高聚噻吩及其衍生物的热电性能。     

N-type doping and thermoelectric properties of co-sublimed cesium-carbonate-doped fullerene

Organic semiconductors exhibit a large Seebeck coefficient and a poor thermal conductivity allowing them to become strong candidates for thermoelectric applications. These materials have been widely used in organic electronics with the fabrication of organic light-emitting diodes, organic solar cells, and transistors. However, few studies have reported on thermoelectric properties of organic materials even though they offer specific advantages such as cost-effectiveness and flexibility. In this article, we discuss the fabrication and characterization of fullerene C60 doped with cesium carbonate (Cs₂CO₃). The evolution of the morphology, electrical conductivity, and Seebeck coefficient was analyzed as a function of the dopant concentration. An optimal power factor of 28.8 μWm^?1 K^?2 was obtained at room temperature for a molar ratio of 15.2 %. Thus far, this power factor value constitutes the best thermoelectric performance achieved with N-type organic materials.     

半导体热电材料研究进展

本文从讨论热电材料的性能出发 ,讨论了提高半导体热电性能的主要途径 ,介绍了主要的半导体热电材料特别是近年来的进展情况 ,展望了其应用前景 ,并提出了亟待解决的问题。     

High Thermoelectric Performance in n-Type Perylene Bisimide Induced by the Soret Effect

Low-cost, non-toxic, abundant organic thermoelectric materials are currently under investigation for use as potential alternatives for the production of electricity from waste heat. While organic conductors reach electrical conductivities as high as their inorganic counterparts, they suffer from an overall low thermoelectric figure of merit (ZT) due to their small Seebeck coefficient. Moreover, the lack of efficient n-type organic materials still represents a major challenge when trying to fabricate efficient organic thermoelectric modules. Here, a novel strategy is proposed both to increase the Seebeck coefficient and achieve the highest thermoelectric efficiency for n-type organic thermoelectrics to date. An organic mixed ion–electron n-type conductor based on highly crystalline and reduced perylene bisimide is developed. Quasi-frozen ionic carriers yield a large ionic Seebeck coefficient of −3021 μV K⁻¹, while the electronic carriers dominate the electrical conductivity which is as high as 0.18 S cm⁻¹ at 60% relative humidity. The overall power factor is remarkably high (165 μW m⁻¹ K⁻²), with a ZT = 0.23 at room temperature. The resulting single leg thermoelectric generators display a high quasi-constant power output. This work paves the way for the design and development of efficient organic thermoelectrics by the rational control of the mobility of the electronic and ionic carriers.     

Fabrication and characterization of thermoelectric thick film prepared from p-type bismuth telluride nanopowders

In this study, bismuth telluride (Bi2Te3)-based nanopowders with particle size ranging from 100 to 300 nm are prepared by high-energy ball milling. Then, the prepared nanopowders are homogeneously mixed with organic binders to form a paste; this paste is used as the raw material to prepare thick-film thermoelectric modules. The thick film prepared by screen printing followed by hot pressing of p-type pastes show reproducible thermoelectric properties, exhibiting an electrical resistivity of 2.0 m Omega cm and a Seebeck coefficient of 298 muVK-1. The prepared p-type Bi2Te3 thick film has a high power factor because its Seebeck coefficient is significantly higher than that of Bi2Te3 based-bulk materials. These results indicate that a thick film prepared from bismuth telluride nanopowders has potential for use as high-performance thermoelectric modules in practical applications such as power generation and cooling system in electronic devices.     

电化学组装一维纳米线阵列p型Bi2Te3温差电材料

：对p型Bi2Te3温差电材料的电沉积过程进行了研究，分析了添加剂对电沉积过程的影响．在此基础上，以孔径为50nm的阳极氧化铝多孔膜为模板，采用直流电沉积技术，在氧化铝多孔模板的纳米级微孔内电化学组装出了P型Bi2Te3纳米线阵列温差电材料，性能研究表明，p型Bi2Te3纳米线阵列的温差电性能远远超过具有相同组成的块状温差电材料。     

Measurements of the seebeck coefficient of thermoelectric materials by an AC method

An ac method for measurement of the Seebeck coefficient was developed. Specimens were heated periodically at frequencies in the range 0.2 10 Hz using a semiconductor laser. The small temperature increase and the resultant thermoelectric power were measured with a Pt Pt 13% Rh thermocouple (25 μm in diameter) through a lock-in amplifier. The Seebeck coefficient of a Pt₉₀Rh₁₀ foil measured by the ac method was in agreement with that obtained from the standard table. The optimum frequency and specimen thickness for the ac method were 0.2 Hz and 0.1 0.2 mm, respectively. The Seebeck coefficients of silicon single crystal and several thermoelectric semiconductors (Si₈₀Ge₂₀, PbTe, FeSi₂, SiB₁₄) measured by the ac method agreed with those measured by a conventional de method in the temperature range between room temperature and 1200 K. The time needed for each measurement was less than a few tens of minutes, significantly shorter than that for a conventional de method. Paper presented at the Fourth Asian Thermophysical Properties Conference. September 5 8. 1995, Tokyo, Japan.