掺杂PbTe基热电材料的粉末冶金法制备及其性能研究

通过溶剂热法制备出立方相PbTe纳米粉末,采用真空封管熔炼法得到PbTe基热电材料Ag0.5Pb8-xSnxSb0.5Te10的合金锭。通过高能球磨得到合金粉末,采用粉末冶金快速热压工艺制备该材料的块体材料。研究了不同Pb/Sn比在300～700K范围内对材料热电性能的影响。研究结果表明,当x=4,电导率在300K时达到1 300S/cm,在600K时达到340S/cm。当x=2,Seebeck系数在625K时达到261μV/K的最大值。功率因子达到15.9×10-4 Wm-1 K-2。     

高电导率小分子热电材料的合成及其热电性能研究

低电导率是限制有机热电材料广泛应用的主要原因.文章设计合成了一种高电导率有机热电材料,4-{2,7-双[4-(4-氟苯基)]-9-(4-磺酰基丁基)-9H-氟-9-基)丁基亚硫酸钾(FPD-PF2),其本征电导率达到23.4 S cm-1.通过旋涂FPD-PF2制备的热电薄膜的载流子迁移达到4.9 cm2 V-1s-1...     

Yb掺杂对热电化合物Ca_(3-x)Yb_xCo_4O_(9+δ)电性能的影响

采用溶胶凝胶法合成Ca3-xYbxCo4O9+δ(x=0,0.15,0.30,0.45)化合物粉体,以粉体为原料结合放电等离子烧结(SparkPlasmaSinte-ring,SPS)制备出致密的块体材料。研究了Yb掺杂对热电化合物电传输特性的影响。结果表明:在300～850K温度范围内,每个样品的See-beck系数又随着温度的升高而单调增大,而Yb取代Ca可使材料的电阻率(ρ)和Seebeck系数同时增加,这是因为三价的Yb3+取代二价的Ca2+将使化合物的载流子浓度降低,当x=0.30时,材料的功率因子最佳,850K时达到0.32×10-3W.K-.2m-1。     

Ni掺杂对β-Cu2Se薄膜微观结构和热电性能的影响

采用磁控溅射的方法和粉末真空烧结的Cu-Se合金靶材,使用高真空磁控溅射技术在单晶Si(100)衬底上制备掺杂Ni的β-Cu₂Se热电薄膜。利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、电子探针和能谱仪(EDS)分别研究薄膜的相组成、表面和截面形貌、微区元素含量与分布。利用塞贝克(Seebeck)系数/电阻分析系统LSR-3测量沉积薄膜的Seebeck系数和电阻率,研究Ni含量对β-Cu₂Se薄膜热电性能的影响。结果表明,使用烧结的Cu-Se合金靶材和利用磁控溅射技术可制备出仅有单一β-Cu₂Se相的薄膜,Ni掺杂没有改变β-Cu₂Se相结构,而是在薄膜中形成替位式固溶体,沉积薄膜具有高度(111)晶面择优取向。在沉积的β-Cu₂Se薄膜中,当Cu与Ni原子含量之和与Se原子含量比(([Cu]+[Ni])/[Se])大于2.0,具有p型导电特征。随Ni含量的增加,沉积β-Cu₂Se薄膜的载流子浓度增加,而载流子迁移率下降。在所研究的温度范围内,掺杂...     

热电材料的研究现状

本文介绍热电材料的种类、制备方法、发展趋势及应用前景,重点讨论几种主要的热电材料的基本结构、性能特征与研究进展.     

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。     

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。     

粉末冶金法制取热电材料

热电材料碲化铋 (Bi2Te3)合金 ,工作温度接近 4 5 0℃ ,可用于制造家用冰箱、空调机、小型探测仪及传感器等。碲化铋可与少量碲化锑 (Sb2 Te3)合金化形成P型半导体固溶体 ,与少量硒化铋(Bi2 Se3)合金化形成N型半导体固溶体。碲化铋、它与其它组分形成的合金都具有高度各向异性的六方结构。拉制碲化铋合金单晶最常用的方法是定向结晶法。可是这种方法生产率低 ,组织偏析 ,且力学性能差。加拿大经过三年研制 ,开发出一种通过粉末冶金途径制造碲化铋合金的方法。它是将直径为 2～ 5mm的粒状纯元素 (Bi,Te ,Se ,Sb等 )粉在球磨机中进行机械…     

化学溶液沉积法制备CazC04O9热电薄膜材料研究

本次实验制备了不同的前驱液,分别利用旋涂法及超声雾化法成功地在SiO2／Si衬底上生长出了Ca3C04O9热电薄膜。利用XRD检测技术对薄膜样品进行了物相分析,用金相显微分析技术分析了薄膜的表观相貌。实验结果表明,在SiO2／Si衬底生长出的Ca3C04O9薄膜具有一定的择优取向,雾化法制备的薄膜样品具有较好的表观质量。     

碘化铯锡半导体热电性能独特北大核心

美国研究人员发现,一种名为碘化铯锡（CsSnI3）的晶体半导体材料具有独特的热电性能,能在保持高电导率的同时,隔绝大部分热量传递。他们在美国《国家科学院学报》上发表文章指出,这种材料的热电性质独特,应用前景十分广阔。碘化铯锡是一种半导体材料,几十年前就被发现,但直到最近几年才受到一些科学家的重视。     

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.     

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.     

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.     

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。     

lectrical Conductivity of Permeable Sintered Materials Composed of Discrete Randomly Oriented Fibers

A theory of the electrical properties of individual contacts is used to calculate the electrical conductivity of porous materials composed of discrete fibers with imperfect interparticle contacts. It is shown that the conductivity of these materials may be substantial even if the contacts are small. The materials' conductivity is significantly affected by a change in the relative length of the fibers.     

Synthesis and Thermoelectric Properties of Ca2.6Nd0.4 Co4O9 Compound

Atemperaturedifferenceappliedacrossasolidgeneratesanelectromotiveforce ,characterizedbythethermoelectricpowerofthesolid .ThisphenomenonisnamedSeebeckeffect .Metaloxidematerialswithhighthermoelectricpropertiesaregoodcandidatesforappli cationtothermoelectricpowergenerationbecausefig ureofmeritZ ,definedasZ =S2 σ/κwhereS ,σ ,κaretheSeebeckcoefficient ,electricalconductivityandthermalconductivity ,respectively ,canevaluatetheperformanceofthermoelectricmaterials .Severalsystemshavebeeninvesti…     

“交叉热线”测量固体材料的热导率:测温热电偶的影响

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Determination of the Thermal Conductivity Coefficient of Superhard Materials

A technique of determining the thermal conductivity coefficient of superhard materials based on the solution of inverse thermal conductivity problems is presented. The design of a heat receiver is developed, in the form of a model comprising thermocouples for experimental determination of a one-dimensional temperature field under the conditions of unidirectional heating. The model is formed from three or four plates (provided with thermocouples) connected together by means of high-temperature cement. Using samples of hexanite-R as an example, application of the newly developed technique for determining the temperature dependence of the thermal conductivity coefficient of the particular material is demonstrated. The technique does not entail the destruction of the plates of superhard materials. Following the tests, the plates may be used for the manufacture of cutting tools.     

Preparation and thermoelectric properties of ternaryrare earth sulfide γ-Ce3-xEuxS4

The effect of Eu-substitution on the density and thermoelectric properties of ternary sulfide Ce3-xEuxS4 (0≤x≤0.8) compacts was investigated. Ce3-xEuxZ4 powders were prepared via the sulfurization of the oxide using CS2 gas at 1473 K. The pressureless sintered Ce3-xEuxS4 compacts in the atmosphere were crystallized in the γ-phase. The density of the Ce3-xEuxS4 compacts increased with the increas-ing of Eu-substitution. Eu-substitution yielded a higher Seebeck coefficient and lower electrical resistivity. The highest value of the thermoe-lectric power factor of 1.41×10-4 W/K2m was obtained for the Ce2.2Eu0.8S4 compact at 673 K. It indicated that Eu-substitution was effective for improving thermoelectric properties of Ce3-xEuxS4.