Research progress of p-type Fe-based skutterudite thermoelectric materials

Filled skutterudite is currently one of the most promising intermediate-temperature thermoelectric (TE) materials, having good thermoelectric transport performance and excellent mechanical properties. For the preparation of high-efficiency filled skutterudite TE devices, it is important to have p- and n-type filled skutterudite TE materials with matching performance. However, the current TE properties of p-type Fe-based filled skutterudite materials are worse than n-type filled skutterudite materials. Therefore, how to obtain high-performance p-type Fe-based filled skutterudite materials is the key to preparation of high-efficiency skutterudite-based TE devices. This review summarizes some methods for optimizing the thermal transport performance of p-type filled skutterudite materials at the atomic-molecular and nano-mesoscopic scale that have been used in recent years. These methods include doping, multi-atom filling, and use of low-dimensional structure and of nanocomposite. In addition, the synergistic optimization methods of the electrical and thermal transport parameters and advanced preparation technologies of p-type filled skutterudite materials in recent years are also briefly summarized. These optimizational methods and advanced preparation technologies can significantly improve the TE properties of p-type Fe-based filled skutterudite materials.     

Thermoelectric power of tellurium thin films and its thickness and temperature dependence

Tellurium thin films of thicknesses between 25 and 200 nm have been vacuum-deposited on glass substrates at room temperature in a vacuum of 5×10^–5torr. The thermoelectric power measurements on these films have been carried out, after annealing, in the temperature range from 300 to about 500 K. It is found from the study that thermoelectric power is independent of temperature and is also, apparently, independent of thickness, over the range of temperatures and thicknesses investigated. The results are discussed on the basis of size effect and thermoelectric effect theories.     

Thermoelectric properties of ZnO-based materials

Abstracts are not published in this journal     

Thermoelectric properties of ultradisperse materials

Formulas for estimating thermoelectric properties in ultradisperse materials are obtained. The possibility of increasing the thermoelectric efficiency is analyzed.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 39, No. 6, pp. 1035–1038, December, 1980.     

Effects of electron-beam and sulfur crosslinking of epoxidized natural rubber on the friction performance of semimetallic friction materials

Semimetallic friction composites (SMFCs) consisting of epoxidized natural rubber (50 mol% epoxidation, ENR 50), alumina nanoparticles, steel wool, graphite, and benzoxazine were prepared via melt mixing using a Haake internal mixer at 90 °C and 60 rpm rotor speed. The composites were vulcanized using sulfur and electron-beam (EB) crosslinking systems. The SMFC samples were then subjected to friction, hardness, porosity, and density tests to determine their friction and wear properties. The morphological changes in the samples were also observed under a scanning electron microscope. The friction and wear properties of SMFCs crosslinked via the EB irradiation and sulfur vulcanization systems were compared. The friction coefficients in normal and hot conditions, as well as the hardness and density of the irradiated SMFC, were higher than those of the sulfur-vulcanized samples at all applied doses. The porosity of the irradiated SMFC at 50, 100, and 150 kGy was higher than that of the sulfur-vulcanized samples; however, the irradiated SMFC exhibited a descending trend at 200 kGy. On the other hand, the specific wear rates of the irradiated samples were lower than those of the sulfur-vulcanized samples at all applied doses. The sample crosslinked via EB irradiation at 150 kGy exhibited the greater tribological property compared with the sulfur-vulcanized SMFC, as indicated by the higher friction coefficient (approximately 0.461) and lower wear rate achieved at 150 kGy irradiation.     

The effect of cobalt, sulfur, and tellurium on the liquidus-solidus gaps of Fe-Ni-Al-Co-Ti alloys

The values of liquidus and solidus temperatures were measured for various permanent magnet alloys including Alcomax III and Hycomax II, III, and IV. The effect of sulfur on these temperatures was studied for each of the alloys, and the effect of tellurium on the temperatures for Hycomax IV was also studied. The effect of liquidus-solidus gaps on columnar crystal formation is discussed. An attempt is made to relate the values found to those obtained from equilibrium diagrams.     

热电制冷膜蒸馏性能及数值模拟分析

为提高膜蒸馏传质过程效率,在新型热电制冷平板式膜蒸馏组件的基础上,对新型半导体冷腔的制冷性能进行分析,通过对具有不同旋向结构参数的热容腔数值模拟计算,获得2mm小空间膜热容腔近膜面处的流场和温度场,比较分析不同边界层涡量值和温度梯度,数值计算结果表明:具有开槽宽度3 mm,角度60.的分水盘的涡量值为0.088 (1/s),温度梯度0.02℃/mm,该结构削弱了膜面处边界层的温度极化和浓度极化,为研究提高膜蒸馏传质通量方法的物理机制奠定了基础.     

锌钛掺杂三氧化钨陶瓷的热电性能

利用传统工艺制备TiO2以及ZnO掺杂的WO3陶瓷,利用X射线衍射以及扫描电镜对其微观结构进行分析,并且在273~973 K进行热电性能的测量,发现晶粒尺寸有着微小的变化,而且有第二相的生成。所有不同浓度的样品在测量范围内均为负值,说明仍是n型氧化物热电材料。实验发现掺杂浓度为0.5%(摩尔分数),温度达到973K时有着最高的功率因子为0.052μW/m·K2。     

热电材料在发电和制冷方面的应用前景及研究进展

本文介绍了热电效应的基本原理 ,阐述了热电材料在发电和制冷方面的应用前景 ,分析了可能具有较高ZT值的几个新概念 ,包括低维热电材料、氧化物热电材料、声子玻璃电子晶体结构材料等     

The preparation and characterization of some skutterudite related compounds

New, skutterudite-related compounds IrGe_1.5S_1.5, IrGe_1.5Se_1.5, IrSn_1.5S_1.5, and RhGe_1.5S_1.5 were prepared by direct combination of the elements at 800°C under conditions of ambient pressure, or by heating the partially reacted elements at 40 Kbars pressure and 600°C. The single-phase products were characterized by X-ray analysis, room temperature magnetic susceptibility determinations and four-probe resistivity measurements. Observed weak superstructure reflections in the X-ray spectra suggest an ordering between the group IVa and group VIa atoms.     

N型Skutterudite化合物BayCo4Sb12的合成及热电性能

用两步固相反应法合成了单相Ba填充式skutterudite化合物BayCo4Sb12.研究了Ba对skutterudite化合物热电性能的影响与CoSb3比较电导率大幅度提高了将近20倍,并且随Ba填充分数的增加电导率增大;塞贝克Seebeck系数较CoSb3有小幅度的下降,但在中高温区域却有一定程度的提高,并且随着Ba填充分数的增加而下降;晶格热导率明显下降;对Ba填充量为0.3的Ba0.3Co4Sb12化合物得到的最大热电性能指数ZT达到0.91.     

Thermomechanical performance of composite materials

Summary A brief review of the status of modelling of thermostructural composites is given, emphasizing topics discussed at the workshop sessions. The perceived needs for new models and techniques to predict composite performance under loading conditions of importance in various industrial applications is discussed, with a summary of recommended areas for focussed near-term research.     

Synthesis and high temperature transport properties of Te-doped skutterudite compounds

Te-doped skutterudite compounds Co₄Sb_12?x Te _x (x?=?0.4–0.7) have been fabricated by solid state reaction method and spark plasma sintering. The scanning electron microscope images indicate all samples are compact and the average particle size increases with the Te doping fraction. The carrier concentration and electrical conductivity exhibit positive doping fraction dependence, and a maximum electrical conductivity of 16.29?×?10⁴?Sm^?1 is obtained at 300?K for Co₄Sb_11.3Te_0.7. The values of the power factor (x?=?0.4–0.6) are greater than 4.0?×?10^?3?Wm^?1?K^?2 at the temperature range of 650–800?K, larger than previous literature reports. The lattice thermal conductivity decreases monotonously over the whole investigated temperature range and exhibits a negative doping fraction dependence except for Co₄Sb_11.3Te_0.7. The resultant dimensionless figure of merit of all the samples increases monotonously over the whole investigated temperature range, and a maximum value of 0.95 is achieved at 800?K for Co₄Sb_11.4Te_0.6.     

The distribution and evaluation of sulfur species in geological materials and manmade fills

Groundwaters containing acidity and/or dissolved sulfate species are a primary factor in the attack on concrete and other construction materials. In the case of concrete, attack may be prevented by the use of suitably resistant concrete, eliminating sources of acidity and/or sulfate ions or by protecting the concrete structure from the offending solutions. Official guidelines, which have recently been modified to take account of the possible formation of sulfate and acidity after construction, are provided for the design of concrete structures to be placed in potentially aggressive situations. Limiting values for sulfates and other chemical species are also given for highway, road and bridge structures, but recent problems involving buried galvanised steel structures have highlighted the need for revised procedures to be put in place. Potential sources of aggressive solutions include the ground surrounding the structure and the construction materials, including fills, situated proximally to the structure.

Unfortunately the current British Standard testing procedures are unsuitable for the purpose of assessing the potential aggressive nature of the ground and construction materials, hence risk assessments prove inadequate. This paper considers potential sources of ground acidity and sulfate rich solutions. Attention is given to suitable testing procedures for the evaluation of sulfur species in geological and construction materials. Particular attention is given to limiting values appropriate to the use of buried steel that forms part of highway, road and bridge structures.