氧分压对ZnO薄膜温差电动势的影响

研究了氧分压对ZnO薄膜温差电动势的影响.用直流反应磁控溅射方法成功地制备了C轴取向性能良好的ZnO薄膜.实验研究发现,温差电动势和磁温差电动势随温度的变化呈线形关系.氧分压越大,温差电动势率越小.研究结果还表明,磁温差电动势比温差电动势小.     

Al掺杂ZnO薄膜的结构和热电性质研究

用直流反应磁控溅射方法在透明平面玻璃上制备出Al掺杂ZnO薄膜,并对其结构和温差电动势率进行研究.实验结果表明,所制备样品具有C轴择优取向的多晶结构,温差电动势随着温差(△T)的增大而呈线性增加.并且样品的电阻越大,温差电动势率越小.在室温附近的环境温度对温差电动势率几乎无影响.退火处理后,温差电动势率增大.实验还发现,在外加磁场时,温差电动势率稍微减小.     

GDARE法制备不同厚度ZnO薄膜的热电性质

以气体放电活化反应蒸发(GDARE)沉积法通过多次沉积制备不同厚度ZnO薄膜。原子力显微镜和X射线衍射测试分析表明,所得ZnO薄膜具有纳米颗粒多晶结构,粒径在30~70 nm,晶粒尺寸随薄膜厚度增加而增大,不同厚度的薄膜均具有高度的c轴取向性。由GDARE法沉积的ZnO薄膜具有较高的温差电动势率S(Seebeck系数),厚度200 nm的薄膜在440K附近S可达600μV/K。相同温度下,薄膜的温差电动势率S与电阻率ρ均随着膜厚的增加而减小。在考察了薄膜电阻率与温差电动势率的综合影响后,得到在440 K附近,厚度为600 nm的ZnO薄膜具有相对最优秀的热电性能。讨论了ZnO薄膜的表面电传导过程及温差电动势产生机制。     

锰-镍金属氧化物半导体材料的温差电动势率

在170～450K 温度范围内测量了具有尖晶石结构的 NiMn_2O_4氧化物半导体材料的温差电动势率 S 和电导率σ与温度的关系。结果表明,温度 T>270K 时,温差电动势率 S 随温度的升高而减小,T<270K 时,S 随温度的升高而增大,即在 T=270K 处 S-1/T 曲线出现拐点,同时电导率σ-1/T 曲线也在该点有明显拐折.分析表明,在 T>270K 时其电导为尾部定域态内的跳跃电导。T<270K 时,为费米能级 E_F 附近定域态内跳跃电导。     

直流磁控溅射制备ZnO薄膜的结构及电学性质研究

本文采用直流反应磁控溅射方法在平面玻璃上制备了ZnO薄膜.所得的ZnO薄膜利用X光衍射,扫描电子显微镜和原子力显微镜进行分析和表征.实验结果表明,ZnO薄膜的结构和电学性质与合成条件密切相关.并测试了ZnO薄膜的温差电动势,得出薄膜中的载流子浓度越大,温差电动势率越小;ZnO薄膜厚度越大,温差电动势率越小.本文对其结果进行了理论分析.     

透明导电CdIn2O4薄膜透光率和Seebeck效应的研究

利用直流磁控反应溅射法在Ar和O2气氛中从Cd-In合金靶上制备了三元化合物CdIn2O1薄膜(CIO),研究了不同氧浓度、基片温度和退火处理对CIO薄膜的透光率的影响以及由温差所产生的Seebeck效应,结果表明:氧浓度、基片温度越高,透光率越高;退火处理进一步提高了透光率,在可见光区域内膜的最高透光率高达95%.研究还发现,CIO薄膜的Seebeck效应非常的明显,温差电动势率最高值达0.16mV/K,这在实际应用方面有参考价值.     

影响CFRC的Seebeck效应的主要因素

研究了炭纤维（ＣＦ）掺量，水泥基体和养护龄期对炭纤维水泥基复合材料（ＣＦＲＣ）Ｓｅｅｂｅｃｋ效应的影响，结果表明，随着ＣＦ增加，温差电动势率出现一极大值，相应的ＣＰ含量为～１．０％，随着养护龄期的延长，温差电动热率趋于稳定；炭纤维含量相同时，水泥基体对温差电动势影响不大。     

国外温差发电器及其能量转换元件研制介绍

一、前言温差电效应也叫热电效应。早在上个世纪,塞贝克、珀尔帖、汤姆逊已分别阐明了热与电之间的三个基本关系。以后又有很多人在这方面进一步进行了研究。但是热电效应的大量应用还是本世纪的事,也还仅限于利用塞贝克效应来测量温度,这也就是我们经常接触的热电偶。随着科学技术的发展,人们对自然界认识进一步深化。从五十年代起,温差电效应有了新的贡献,温差发电、温差致冷的技术很快的发展起来了。这里我     

热电材料的发展

一、前言热电材料是指具有特殊热电性能,用来制造热电偶温度传感器的感温元件或制造温差发电器和温差致冷器的换能元件的一大类功能变换材料。这些材料的功能原理虽然都是热电效应,由于具体应用不同,性能要求各异,又可再分为热电偶材料和温差电材料两类。众所周知,热电偶是目前应用最广的一种温度传感器。其工作原理是基于塞贝克热电效应,即由两种不同的导体组成闭合热电回路,当两个接点处在不同的温度时,回路中有热电流流动。当回路断开而不闭合时,在断开的回路两端出现一个电动势E_(ab)(T,T_0),它是两接点的温度T和T_0的函数,也与组成回路的两种导体的材质有关(如图1)。当T_0置于     

基于塞贝克效应的半导体气敏传感器的研制

利用塞贝克效应研制成功ZnO半导体气敏传感器。这种新型传感器能够输出0-100mV的直流电压,对于信号的放大与处理将十分方便。在实验中对20×10-6NO2气体进行检测,结果表明:传感器的输出电压(温差电动势),随着待测气体浓度而变化。因此,利用温差电效应制作气敏传感器是一条完全可行的新思路。     

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.     

Temperature variation of thermoelectric power of vacuum deposited PbSe thin films and its thickness dependence

PbSe thin films of thicknesses in the range 20 to about 170 nm have been prepared on glass substrates held at room temperature by thermal evaporation of the bulk alloy at a pressure of 5×10^–5 torr. The thermoelectric power of these films has been evaluated as a function of temperature in the range 300 to 500 K from the thermal e.m.f. data. It was found that the thermoelectric power of all the films initially increases with increasing temperature, then reaches a maximum, and, with a further increase in temperature, decreases rapidly and also changes sign. The possible reasons for this peculiar behaviour have been given. It is also found that there is no systematic variation of thermoelectric power with thickness of the films. This is probably due to completely specular scattering at the external and internal surfaces of PbSe thin films or to changes in stoichiometry of different films.     

Performance of Bi–Te–Sb–Se Thermoelectric Material at Low Temperature

Thermoelectric materials are of interest for applications as heat pump and power generators. The performance of a thermoelectric material, the figure of merit, ZT, is measured. The figure of merit is interrelated to the thermal conductivity, electrical conductivity, and Seebeck coefficient. All of these parameters are functions of temperature. The performance of a Bi–Te–Sb–Se thermoelectric material at low temperature was studied experimentally in this work. Based on the experimental results, the relation between various parameters and temperature, and the figure of merit are reported. The conclusions indicate that this thermoelectric material is not suitable for power generation at low temperature, and only an improvement of production technology or the development of a new production method can improve the electrical power generation performance with this method.Paper presented at the Seventh Asian Thermophysical Properties Conference, August 23–28, 2004, Hefei and Huangshan, Anhui, P. R. China.     

温差发电的热力过程研究及材料的塞贝克系数测定

建立了半导体温差发电器件的基本模型；从稳态的热传导方程出发，对发电器件进行了热力学分析，推导出P型和N型半导体内部的温度分布函数及输出功率和发电效率的表达式；测定了一种Bi-Te-Sb-Se半导体热电材料在低温下的塞贝克系数随温度的变化关系，绘制了曲线并进行数值拟合；结果表明，该种半导体热电材料在低温下性能不佳，需改进配方或生产工艺方可使用。     

Size and temperature dependence of thermoelectric power and electrical resistivity of vacuum-deposited antimony thin films

Thin antimony films of thicknesses in the range 30 to 200 nm have been vacuum deposited on glass substrates at room temperature. After annealing for about an hour at 500 K, the thermoelectric power and electrical resistivity were measured in vacuum as a function of temperature. The thermoelectric power and electrical conductivity data were combined and simultaneously analysed using the effective mean free path theory of size effect in thin films developed by Tellier and Pichard et al. In addition, their temperature dependence was also analysed. It was found that the thermoelectric power is positive and increases with increasing temperature and is inversely proportional to the thickness of the film. The electrical resistivity was found to be temperature dependent with the temperature coefficient of resistivity being positive, and inversely proportional to the thickness of the film. Analysis combining the data from the thermoelectric power and electrical conductivity measurements has led to the determination of mean free path, carrier concentration, effective mass, Fermi energy and the parameter The data were analysed for least squares fitting by local functions, such as the spline functions, which eliminates possible errors in conventional least squares fitting of data using non-local functions valid throughout the range.     

Enhancement of high temperature thermoelectric properties of intermetallic compounds based on a Skutterudite IrSb3 and a half-Heusler TiNiSb

Phonon glass and electron crystal (PGEC) thermoelectric materials have been expected to be a new class of thermoelectric materials for high temperature applications. Among the efforts to optimize the high temperature thermoelectric properties of various PGEC thermoelectric materials, recent experimental works on the Skutterudite IrSb₃ and half-Heusler TiNiSb intermetallic compounds are presented herein by which the material design concept for high energy conversion efficiency, i.e. a high figure of merit, is suggested. It is revealed that the thermoelectric efficiency of IrSb₃ can be increased by the decrease of lattice thermal conductivity due to the rattling effect of La atoms filled in the structural vacancies of the Skutterudite crystal structure. In the half-Heusler TiNiSn, high temperature thermoelectric properties are improved by Hf substitution to the Ti sites by reducing lattice thermal conductivity and also by Sb doping to increase power factor. It is concluded that the proper alloy designing for controlling crystal structure and carrier concentration could enable these intermetallic compounds to exhibit a high potential for elevated temperature thermoelectric applications.     

Enhancement of high temperature thermoelectric properties of intermetallic compounds based on a Skutterudite IrSb3 and a half-Heusler TiNiSb

Phonon glass and electron crystal (PGEC) thermoelectric materials have been expected to be a new class of thermoelectric materials for high temperature applications. Among the efforts to optimize the high temperature thermoelectric properties of various PGEC thermoelectric materials, recent experimental works on the Skutterudite IrSb₃ and half-Heusler TiNiSb intermetallic compounds are presented herein by which the material design concept for high energy conversion efficiency, i.e. a high figure of merit, is suggested. It is revealed that the thermoelectric efficiency of IrSb₃ can be increased by the decrease of lattice thermal conductivity due to the rattling effect of La atoms filled in the structural vacancies of the Skutterudite crystal structure. In the half-Heusler TiNiSn, high temperature thermoelectric properties are improved by Hf substitution to the Ti sites by reducing lattice thermal conductivity and also by Sb doping to increase power factor. It is concluded that the proper alloy designing for controlling crystal structure and carrier concentration could enable these intermetallic compounds to exhibit a high potential for elevated temperature thermoelectric applications.     

Synthesis and properties of Na<Subscript> <Emphasis Type="Italic">x</Emphasis> </Subscript>CoO<Subscript>2</Subscript> (<Emphasis Type="Italic">x</Emphasis> = 0.55, 0.89) oxide thermoelectrics

Na_xCoO₂ (x = 0.55, 0.89) sodium cobaltites have been prepared by solid-state reactions; their structural parameters have been determined; their microstructure has been studied; and their thermal (thermal expansion, thermal diffusivity, and thermal conductivity), electrical (electrical conductivity and thermoelectric power), and functional (power factor, thermoelectric figure of merit, and self-compatibility factor) properties have been investigated in air at temperatures from 300 to 1100 K. The results demonstrate that, with increasing sodium content, the electrical conductivity and thermoelectric power of the materials increase and their thermal conductivity decreases. As a result, the power factor and thermoelectric figure of merit of the Na_0.89CoO₂ ceramic at a temperature of 1100 K reach 0.829 mW/(m K²) and 1.57, respectively. The electron and phonon (lattice) contributions to the thermal conductivity of the ceramics have been separately assessed, and their linear thermal expansion coefficients have been evaluated.     

Characterization of Thermoelectric Modules for Powering Autonomous Sensors

The characterization of three commercial thermoelectric modules, which are designed for cooling/heating applications, is presented to employ the devices for power conversion, i.e., as thermoelectric generators (TEGs). The thermoelectric theory is briefly summarized at first, taking into account the relationship between the effective temperature difference across the TEG junctions and the temperature difference applied externally, considering insulating ceramic plates having finite thermal conductance. The thermoelectric modules have been characterized in terms of open-circuit output voltage and output power density for different temperature gradients and load conditions. Measurement techniques and experimental data are reported, which show the possibility of using thermoelectric devices for energy-harvesting applications. A comparison of the results from the tested devices with the performance data of commercial TEGs that are specifically designed for power harvesting is then presented, and the main characteristics of the two device typologies are discussed. A TEG was then used to supply an autonomous system that interfaces with a temperature sensor and periodically transmits the measurement information via an RF link. Experimental data show that the system works correctly and sends the RF signal when the temperature difference that is applied across the TEG is higher than 34 K.      

Transport properties of cold-worked aluminum at low temperatures

The electrical resistivity and thermoelectric power in annealed and cold-worked samples of Al and Al-Mg alloy have been measured between1.5 and8.5 K. The deviation from Matthiessen's rule is found to decrease with cold work, while the residual resistivity increases. The lattice imperfections also have strong effects on the thermoelectric power. A critical discussion focuses on the relation of and discrimination among these effects.