铜基类金刚石结构化合物热电性能研究进展

新能源热电转换技术因其在废热回收、热电制冷、航空航天等领域的广泛应用,面向国家重大需求、助力实现“碳达峰、碳中和”而受到广泛关注。有效提升材料的综合热电性能对拓宽热电材料的应用具有深远的意义。铜基类金刚石结构热电材料因其易于调控的输运特性、高元素丰度和低毒等优点引起了研究者的兴趣,因此总结铜基类金刚石结构热电材料研究进展对提升其性能具有重要的指导意义。本文总结了铜基类金刚石结构系列化合物的晶体结构演变过程、能带结构和声子谱特征;归纳了基于能带结构优化和载流子浓度优化来提升电输运性能的研究概况;概括了本征低晶格热导率的机理和利用声子工程优化热输运性能的规律。最后,总结了铜基类金刚石结构化合物热电材料的优势和目前性能优化的瓶颈,并展望了可能的进一步优化策略。     

热电氧化物的制备和性能研究进展

近年来，由于热电氧化物具有优良的性能，适合于在空气气氛和高温环境中工作，无毒性，无环境污染等问题，制作简单，可以直接在空气中烧结，不需真空等优点，而受到了广泛的关注。对热电氧化物的各种制备方法进行了概述和评论，重点介绍了热电氧化物新的制备方法及其性能研究进展，并对未来发展前景进行了分析，通过掺杂碱金属、碱土金属和稀土等元素提高氧化物的电导率，细化晶粒降低热导率，从而制备高性能的热电氧化物陶瓷材料。     

Bi2Te3基热电材料输运性质优化策略研究进展

随着能源需求的持续增长和不可再生资源的不断耗竭,世界各国高度关注新型能源的开发,同时也致力于提高工业废热的回收率和利用率。热电材料是一种能够实现热能和电能直接转换的固态介质,以其为核心的热电器件不含运动附件且不排放污染物,已在半导体制冷和局部热管理领域实现商业化,例如户外制冷机、车载冷柜、光电芯片和功率激光器的控温装置等。热电制冷非常适于小空间热源的主动冷却,可能成为下一代通讯和信息技术的热管理难题中唯一可行的解决方案。Bi2Te3基化合物作为近室温区兼具稳定理化性质和优异输运性质的热电材料,一直受到学术界和产业界的广泛关注。本文在概述热电材料研究背景和制备方法的基础上,从能带工程、声子散射工程、热变形工艺、结构低维化等方面对热电性能的优化方法进行了归纳,并对未来机遇进行了展望。     

退火对CoSb3块体热电性能的影响

采用烧结和退火工艺制备了CoSb3块体热电材料，并探讨了退火对热电性能的影响。用X射线衍射分析了样品的相组成，用电常数测试仪和激光热导仪测试了样品的热电性能。结果表明，退火前后样品具有相同的相组成，其电阻率随着温度的升高而降低，具有典型的半导体电学特征；在相同温度下退火样品的ZT值低于或近似于未退火的样品，因此退火对于提高和改善CoSb3块体材料的热电性能没有明显作用。     

热电转换材料与β—FeSi2

本文简述了热电转换材料研究工作的状况，分析了β-FeSi2制备及提高其热电转换性能的途径，认为机械合金化是制备β-FeSi2较好的方法。     

一些稀土硫族化物的制备和热电性能

稀土倍半硫族化物(R_2S_3,R_2Se_3,R_2Te_3)是在高温下具有良好热电量能的一类化合物,因为热电发电的效率,随热电元件热端和冷端温差的增加而增大,所以都希望在热电转换器中采用高温半导体。从这个角度上,稀土倍半硫族化物在科学和技术方面受到了重视。     

机械合金化结合放电等离子烧结技术制备热电材料的研究进展

近年来,热电材料研究取得重要突破,不仅传统Bi₂Te₃、PbTe基热电材料性能得到提升,同时还发现一批新型高性能热电材料,如SnSe、GeTe等。热电材料性能的提升不仅取决于材料成分、结构及缺陷,还与制备工艺密不可分。机械合金化（mechanical alloying,MA）结合放电等离子体烧结（spark plasma sintering,SPS）的粉末冶金技术是制备热电材料的重要方法,该方法简单、高效,获得的晶粒尺寸较小,同时可以引入纳米结构和缺陷,有助于降低晶格热导率,获得高热电性能。此外,基于机械合金化结合放电等离子体烧结技术制备出的块体材料具有更优的力学性能,可以有效地增强热电器件的使用寿命。本文介绍了机械合金化与放电等离子体烧结方法制备热电材料的基本原理和关键影响因素,并概述了利用该方法制备的碲化物、硫化物和硒化物基热电材料的研究进展。     

Mn3(Cu0.53Ge0.47)N的负热膨胀现象与物性研究

通过氮气保护气氛下固相烧结法制备出Mn3(Cu0.53Ge0.47)N化合物.XRD结果表明,该化合物具有立方的反钙钛矿结构.热膨胀分析表明,试样在200～233 K具有很强的负热膨胀性能,平均热膨胀系数达到-93×10-6/K.利用超导量子干涉磁强计(SQUID)和多功能物性测量系统(PPMS)分别测量试样的磁性和比热容,热电势等物性,结果显示Mn3(Cu0.53Ge0.47)N化合物具有晶格、白旋、电子相关联性,负热膨胀是由于反铁磁性自旋结构逐渐地向顺磁转变过程中引起的磁容积效应所导致的.     

金属间化合物的机械合金化制备

综述了机械合金化制备金属间化合物的研究进展，指出了机械合金化技术在金属问化合物制备方面的优势。简述了机械合金化形成金属问化合物的机理，重点介绍了平衡相金属间化合物、弥散强化金属问化合物、过饱和金属问化合物，非晶合金、纳米晶材料等几类机械合金化金属间化合物的制备与组织性能。并针对目前研究的不足以及该研究领域的发展方向提出了加强MA过程热力学和动力学的基础理论研究、改良MA工艺等建议．     

高炉冲渣水余热半导体热电发电模型与数值模拟

 针对中国钢铁工业低温余热回收利用率低的现状,提出一种基于半导体热电发电技术回收高炉冲渣水显热的技术方案,建立了相应的计算模型,分析了冲渣水温度、热电单元长度、热电模块填充系数、换热器流道长度等关键参数与装置性能的关系。结果表明,对于100 ℃的高炉冲渣水,利用热电发电技术,每米流程可使水温下降约1.5 ℃,每平方米换热面积可以产生约0.93 kW电能,热效率约为2%,设备成本的回收周期在10年左右。     

Enhancement of Thermoelectric Behavior of La0.5Co4Sb12−x Te x Skutterudite Materials

Metallurgical and Materials Transactions A - In this work, the effects of Te doping on the microstructure and thermoelectric properties of the partially filled skutterudite La0.5Co4Sb12 compounds...     

DFT studies of thermoelectric properties of R–Au intermetallics at 300 K

Thermoelectric and electronic properties of cubic bi-intermetallics R-Au(R = Tb, Ho. Er. Tm and Yb)compounds were explored. Electronic properties i.e. density of states and band structure were computed using first principles calculations which proved the metallic nature of these compounds. Post-DFT(BoltzTraP) calculations were carried out to explore their thermoelectric properties like electrical conductivities. Seebeck coefficient, electronic thermal conductivities and figure of merit. The highest Seebeck coefficient and figure of merit were found for YbAu among these compounds which are 105 μV/K and 0.285 respectively. All the calculations were carried out at 300 K. Large values of figure of merit obtained for these compounds at room temperature indicate that these materials can be used for thermoelectric devices however need experimental verification.     

Thermoelectric properties of Yb x Co_4 Sb_（12） system

Yb x Co 4 Sb 12 polycrystals were fabricated by vacuum melting combined with hot-press sintering.The effect of Yb-filling on thermoelectric property of unfilled skutterudite CoSb 3 was investigated,which indicated the enhancement of the power factor of the material.Transport properties of materials changed from semi-conductor to semi-metal during the measurement of electrical conductivity,which indicated the change of electronic band structure.The maximum value of electrical conductivity was about 190000 S/m at 300 K for all samples.On the basis of Yb-filling,power factor of Yb 0.2 Co 4 Sb 12 reached 5-6 mW/(m·K) during the measurement temperature.Thermal conductivity decreased with increase of Yb content,and the thermal conductivity of Yb 0.2 Co 4 Sb 12 reached 3.2 W/(m·K) at 600 K.The ZT value of Yb 0.2 Co 4 Sb 12 reached 1.16 at 700 K due to positive contribution from high power factor and low thermal conductivity.     

Thermoelectric Properties of CexCo4Sb12 Prepared by MA-SPS

Starting with elementary powders, thermoelectric materials CexCo4Sb12 were prepared by mechanical alloying and spark plasma sintering (MA-SPS). XRD analyses reveal that the expected major phase, named skutterudite was formed in MA process and was kept after SPS. The thermoelectric properties of MA-SPS samples including resistivity, Seebeck coefficient, power factor, thermal conductivity and the dimensionless figure of merit (ZT) were studied by varying Ce content and temperature. Depending on Ce levels, both P and N types of thermoelectric semiconductors were obtained. MA-SPS sintered Ce1.0Co4Sb12 exhibits the highest ZT in the range of 100-500℃ and the maximum ZT is found at x=1.0 and 400℃.     

HPHT synthesis and electrical transport properties of SmxCo4Sb12

Samarium-filled skutterudites SmxCo4Sb12(x=0.5,1.0) skutterudite thermoelectric(TE) materials with enhanced power factor were prepared by high-pressure and high-temperature(HPHT) technique.The microstructure properties were characterized with X-ray diffraction and scanning electron microscopy.The electrical resistivities and Seebeck coefficients of those samples were measured in the temperature range of 300-723 K,and the samples of SmxCo4Sb12 showed n-type conduction.The Seebeck coefficient in absolute valu...     

Crystal Structures and Thermoelectric Properties of Sm-Filled Skutterudite Compounds Smy Fex Co4 - x Sb12

Polycrystalline samples of Sm partially filled skutterudites SmyFexCo4-xSb12 were prepared by melting and Spark Plasma Sintering technique. The results of Rietveld refinement showed that the obtained SmyFexCo4-xSb12 samples possessed filled skutterudite structures. The thermal parameter （B） of Sm is larger than that of Sb, Fe, and Co, indicating that Sm ＂rattled＂ in Sb-icosahedron voids. The effects of filling atom Sm on thermoelectric properties of these compounds were investigated. With the increase of Sm filling fraction （y）, electrical conductivity decreased, Seebeck coefficient increased and had a maximum value when y was 0.38; thermal conductivity reduced and had a minimum value when y was 0. 32. At 750 K, the highest figure of merit of 0.68 was obtained for Sm0.32Fe1.47Co2.53Sb12.     

Thermoelectric properties of LaFe_3CoSb_(12) skutterudite materials with different nanostructures

Nanostructures with different morphologies could profoundly influence the electron and phonon transport in thermoelectric materials and thus their properties could be improved by tuning the nanostructures.The LaFe3CoSb12 skutterudite nano powders with differentmorphologies were fabricated via a hydro/solvo thermal route.The microstructures of the hot-pressed LaFe3CoSb12 bulks were characterizedthrough X-ray diffraction(XRD) and scanning electron microscopy(SEM) and the effects of the nanostructures on the thermoelectric properties were investigated by measuring the electrical conductivity,the Seebeck coefficient and the thermal conductivity.The results suggestedthat the mixed morphology of nanorods and nanospheres could enhance the electrical conductivity largely although the Seebeck coefficientwas decreased and the thermal conductivity was increased slightly.Differently,a higher Seebeck coefficient,a lower thermal conductivity anda lower electrical conductivity could be obtained for the LaFe3CoSb12 bulk with a single morphology of nanospheres.Consequently,the figure of merit of LaFe3CoSb12 bulk with a mixed morphology of nanorods and nanospheres could be increased by about 59% as compared tothat with a single morphology of nanospheres.     

Oxidation Behavior of the Skutterudite Material Yb0.2Co4Sb12

Metallurgical and Materials Transactions A - The skutterudite materials belonging to the CoSb3 family are widely studied for thermoelectric applications. They are typically used under vacuum, but...     

Effect of Y-filling on thermoelectric properties of CoSb3

The CoSb3 and Y0.18Co4Sb12 compounds were synthesized by a metallurgical route. Their bulk materials were prepared by the hot-pressed process under vacuum. Thermoelectric properties of the samples were measured by the thermoelectric measurement system and the laser flash diffusivity apparatus. The carrier type conversion of hot-pressed CoSb3 was found at about 530 K, while the conversion was missed for the Y0.18Co4Sb12 sample. Electrical conductivity of the Y0.18Co4Sb12 sample increased due to the increase of carrier concentration, and its thermal conductivity decreased due to the enhancement of phonon scattering. The value of ZT, figure of merit, for the Y0.18Co4Sb12 sample was obviously enhanced due to positive contribution of the electrical conductivity and the thermal conductivity.