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1.
Bi2Te3薄膜是室温下热电性能最好的热电材料,利用磁控溅射在长有一薄层SiO2的n型硅样品上制备Bi/Te多层复合薄膜,经后续退火处理生成Bi2Te3。通过分析Bi2Te3薄膜的生长和退火工艺,探讨Bi/Te中Te的原子数分数对薄膜热电性能的影响。采用XRD和SEM对薄膜的结构、形貌和成分进行分析,并测量不同条件下的Seebeck系数。薄膜Seebeck系数均为负数,表明所制备样品是n型半导体薄膜,且最大值达到-76.81μV.K-1;电阻率ρ随Te的原子数分数增大而增大,其趋势先缓慢后迅速。Bi2Te3薄膜的热电性能良好,Te的原子数分数是60.52%时,功率因子最大,为1.765×10-4W.K-2.m-1。  相似文献   

2.
为了提高Bi2Te3热电材料的性能,采用Bi2Te3纳米粉体前驱物快速熔炼烧结法,制备了在室温条件下具有温度敏感性的Bi2Te3合金材料,在425K时此材料的热电优值达到0.548。在此基础上,研制了热电模块,并对其性能进行了测试。结果表明,以该Bi2Te3合金材料制备的热发电模块具有良好的伏安特性和稳定的内阻,当热冷端温度分别为140和60℃时,模块的最大输出功率可达到0.39W,显现出潜在的应用前景。  相似文献   

3.
随着全球经济对高效、无污染能源转换的强劲需求,Bi2Te3半导体作为最优异的室温热电材料取得了长足稳步的发展。本文在简述Bi2Te3热电材料的结构和性能的基础上,重点介绍了掺杂、纳米化、掺杂与纳米化相结合的方法对Bi2Te3热电性能的影响,详细分析了其影响机制。结果表明,以上方法均能很大程度上提升Bi2Te3热电材料的热电性能,尤其是掺杂与纳米化相结合对热电性能的提高更为显著。最后,对Bi2Te3热电材料改性的研究方向进行了展望。  相似文献   

4.
采用助熔剂法合成Ca3Co3.9Cu0.1O9粉体。添加Bi2O3作为助烧剂,通过直流快速热压获得块体,熔融的Bi2O3能够促进Ca3Co3.9Cu0.1O9片流动以完成致密化过程,再通过液相反应烧结制备出了Ca3Co3.9Cu0.1O9/Bi2Ca2Co2Oy复合热电材料,对其物相组成、微观结构和热电性能进行了表征。结果表明,添加Bi2O3提高了样品的密度,降低了材料的电阻率,复合材料的功率因子在973 K时达到4.12×10–4 W·m–1·K–2。  相似文献   

5.
以Zn(NO3)2·6H2O、NaOH为原料,在乙醇–水混合溶液体系中,采用直接沉淀法合成了ZnO纳米粒子。并借XRD分析研究了该ZnO纳米粒子的晶粒度及晶格畸变等相关结构参量。XRD和SEM分析测试表明:当热处理温度高于100℃时,可以合成ZnO纳米粒子。热处理温度由100℃升至300℃,ZnO纳米粒子晶粒度将由35nm增大到约63nm,且纳米粒子形貌不随温度变化而变化。另外,随着ZnO纳米粒子晶粒度的增大,其晶格常数和晶格畸变量变小。  相似文献   

6.
采用共沉淀法制备了CoFe2O4纳米颗粒,运用XRD、TEM和VSM测试手段,研究了煅烧温度对CoFe2O4的结构、形貌以及磁性能的影响。结果表明:CoFe2O4纳米颗粒的粒径大小均匀;煅烧前与经200℃和600℃煅烧的CoFe2O4纳米颗粒晶粒度分别约为15,20和30nm;CoFe2O4纳米颗粒的粒径、Ms、Mr和Hc随着煅烧温度的升高而增大。当煅烧温度为600℃时,Ms约为67A·m2·kg–1,Hc为4.67×107A·m–1。  相似文献   

7.
采用sol-gel法制备了掺Cu的钴酸钙(Ca3Co4O9)热电材料,研究了Cu掺杂量对其物相、电导率σ、Seebeck系数S和功率因子P的影响。结果表明:随着Cu掺杂量的增加,试样中Ca3Co4O9的含量下降,但试样的电导率增加;试样的Seebeck系数和功率因子先增加后下降。试样(Ca0.90Cu0.10)3Co4O9在973 K时的功率因子最大,为15.3×10–4 W.m–1.K–2。  相似文献   

8.
空间近日等强辐照造成的高温严重影响光伏电池的转化效率,同时造成辐射能量的浪费.以单晶Si光伏电池和Bi2Te3热电电池为基本单元,构建Si-Bi2 Te3光热耦合电源器件模型.采用有限元分析法分析特定辐射条件下Si-Bi2Te3光热耦合电源器件的热分布情况,并结合光伏电池与热电电池的温度特性进一步计算了器件的转化效率.结果显示,Bi2Te3热电池的存在一定程度上降低了Si光伏电池的工作温度,在空间环境下Si-Bi2Te3光热耦合电源器件的转化效率相对于单一的Si光伏电池有2% ~3%的提高.最后讨论了该器件Si光伏电池和Bi2Te3热电池的功率输出方式.  相似文献   

9.
采用电场激活压力辅助烧结(FAPAS)技术制备了(Bi2Te3)0.2(Sb2Te3)0.8热电材料,采用无电场、低电场强度和高电场强度三种烧结方式作为对比实验,研究了烧结过程中施加电场强度对(Bi2Te3)0.2(Sb2Te3)0.8热电材料微观结构和热电性能的影响。研究结果表明,在烧结过程中施加电场,可明显提高(Bi2Te3)0.2(Sb2Te3)0.8热电材料的电导率和Seebeck系数,从而提高其综合电功率因子;而采用大电场强度烧结则会使(Bi2Te3)0.2(Sb2Te3)0.8材料出现层状结构择优取向,在电性能相对较高的情况下亦使其热导率明显减低,从而获得较高ZT值。  相似文献   

10.
Bi2Te3热电材料研究现状   总被引:1,自引:0,他引:1  
Bi2Te3热电材料是半导体材料,室温下具有良好的热电特性,能够实现热能和电能的相互转化,应用前景十分广阔。Bi2Te3热电材料的转换效率低是影响其应用的瓶颈之一,目前世界范围内的研究热点主要集中在如何提高热电材料的能量转换效率上。综述了热电材料的种类、国内外关于Bi2Te3热电薄膜的制备方法和性能研究,对多种典型制备方法进行分析对比,探讨了影响Bi2Te3热电薄膜质量的因素及机制。结合Bi2Te3热电薄膜在温差发电和热电制冷方面的应用,如果微型热电制冷器实现与大功率LED芯片集成封装,那么芯片级低温散热问题有望解决。  相似文献   

11.
In this work, Bi2Te3 films (250 nm) are fabricated on SiO2/Si substrates by radio frequency (RF) magnetron sputtering at room temperature, and the prepared films are annealed over the temperature range of 200 ℃ to 400 ℃. Crystallinity and electrical properties of the films can be tuned correspondingly. The power factors of Bi2Te3 films of 0.85 W/K2cm to 11.43 W/K2cm were achieved after annealing. The infrared reflectance measurements from 2.5 m to 5.0 m demonstrate that there is also a slight red-shift of the plasma oscillation frequency in the Bi2Te3 films. By means of plasmonic calculations, we attribute the red-shift of absorption peaks to the reduction of carrier concentration and the change of effective mass of Bi2Te3 films with the increased annealing temperature.  相似文献   

12.
We have investigated the origin of crystal orientation for nanocrystalline bismuth telluride-based thin films. Thin films of p-type bismuth telluride antimony (Bi–Te–Sb) and n-type bismuth telluride selenide (Bi–Te–Se) were fabricated by a flash evaporation method, with exactly the same deposition conditions except for the elemental composition of the starting powders. For p-type Bi–Te–Sb thin films the main x-ray diffraction (XRD) peaks were from the c-axis (Σ{00l}/Σ{hkl} = 0.88) whereas n-type Bi–Te–Se thin films were randomly oriented (Σ{00l}/Σ{hkl} = 0.40). Crystal orientation, crystallinity, and crystallite size were improved for both types of thin film by sintering. For p-type Bi–Te–Sb thin films, especially, high-quality structures were obtained compared with those of n-type Bi–Te–Se thin films. We also estimated the thermoelectric properties of the as-grown and sintered thin films. The power factor was enhanced by sintering; maximum values were 34.9 μW/cm K2 for p-type Bi–Te–Sb thin films at a sintering temperature of 300°C and 23.9 μW/cm K2 for n-type Bi–Te–Se thin films at a sintering temperature of 350°C. The exact mechanisms of film growth are not yet clear but we deduce the crystal orientation originates from the size of nano-clusters generated on the tungsten boat during flash evaporation.  相似文献   

13.
Starting with a BST (Ba0.6Sr0.4TiO3) nanopowder with a mean diameter of about 50 nm, the average grain size increases from the nanometer to the micrometer range (from 70 nm to 1–2 μm) by thermal annealing between 700 and 1400 °C. The dielectric properties of these pressed powders has been determined, showing that the temperature of transition decreases with grain size. In order to check this evolution in dense ceramics in which the grain size is conserved, composite materials based on ferroelectric nanograins and a non‐ferroelectric matrix have been prepared. Core–shell composites with different core sizes (150 and 50 nm) were synthesized in this way and the results obtained confirmed the decrease of the transition temperature with grain size, from 290 to 230 K respectively. Furthermore, dielectric losses are very weak in these core–shell composites—at between 0.1 and 1 % in the temperature range 150–450 K and the frequency range 1 × 103–1 × 105 Hz. Ferroelectric nanograins of BST were also incorporated into silica gel for comparison with the core–shell materials. Even for a high fraction of BST (approx. 75 %), the properties of the grains are masked by the presence of silica, which possesses a very low dielectric constant. This study has allowed the possible determination of the macroscopic dielectric properties in nanostructured ceramics.  相似文献   

14.
In this work, we highlight new materials processing developments and fabrication techniques for dispenser-printed thick-film single-element thermoelectric generators (TEG). Printed deposition techniques allow for low-cost and scalable manufacturing of microscale energy devices. This work focuses on synthesis of unique composite thermoelectric systems optimized for low-temperature applications. We also demonstrate device fabrication techniques for high-density arrays of high-aspect-ratio planar single-element TEGs. Mechanical alloyed (MA) n-type Bi2Te3 powders were prepared by taking pure elemental Bi and Te in 36:64 molar ratio and using Se as an additive. X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques were used to characterize the as-milled powders to confirm the Bi2Te3 phase formation and particle size below 50???m. Thermoelectric properties of the composites were measured from room temperature to 100°C. We achieved a dimensionless figure of merit (ZT) of 0.17 at 300?K for MA n-type Bi2Te3?Cepoxy composites with 2?wt.% Se additive. A 20 single-leg TEG prototype with 5?mm?×?400???m?×?120???m printed element dimensions was fabricated on a polyimide substrate with evaporated gold contacts. The prototype device produced a power output of 1.6???W at 40???A and 40?mV voltage for a temperature difference of 20°C.  相似文献   

15.
用sol-gel法粉体技术和化学镀膜技术的微观复合,在溶液中得到超细CaSiO3导电粉。讨论了醛基溶液浓度、溶液pH值对导电粉性能的影响,确定了导电粉制备的工艺条件为:n(CaSiO3粉体)∶n(Tollen试剂)=1∶1,且pH=9。用SEM/EDS对粉体形貌和元素组成进行表征和分析,得出CaSiO3导电粉体粒径为30~50μm,体积电阻率在10–6?·m以下。  相似文献   

16.
Two- (2D) and three-dimensional (3D) growth of nanostructured Bi2Te3 films was performed on 4° tilt (100) GaAs substrates using a metalorganic chemical vapor deposition system. To obtain 3D Bi2Te3 crystallites embedded in 2D planar film, we alternately changed the gas flow rate in the reactor. By repeating two steps, 3D Bi2Te3 crystallites embedded in 2D planar Bi2Te3 film were obtained. The thermoelectric properties in terms of the thermal conductivity, electrical conductivity, and Seebeck coefficient were investigated at room temperature. The thermal conductivities of the nanostructured Bi2Te3 films were from 0.63?W/(m?K) to 0.94?W/(m?K) at room temperature, which are low compared with that of film without nanostructure [1.62?W/(m?K)]. The thermal conductivity of the film was effectively decreased with the decrease of size and increase of density of 3D crystallites. The results of this study open up a new method to fabricate nanostructured thermoelectric films with high thermoelectric figure of merit.  相似文献   

17.
采用Pechini法制备了100 nm的Ba0.7Sr0.3TiO3纳米粉体,并用凝胶注模成型工艺制备不同Mn含量的BST陶瓷。研究表明,在Mn掺杂量为0.5%(摩尔分数),烧结温度为1 280℃时制备的样品,其热释电性能较好,在居里温度附近,30~40℃时,其平均热释电系数为450μC.m–2.K–1,对应平均探测率优值为5.6μC.m–3.K–1,1kHz频率条件下tanδ低于0.5%,εr为3 500左右(室温20℃,外加偏压200 V/mm)。  相似文献   

18.
A thermopile sensor was processed on a glass substrate by electrodeposition of n-type bismuth telluride (Bi-Te) and p-type antimony telluride (Sb-Te) films. The n-type Bi-Te film electrodeposited at −50 mV in a 50 mM electrolyte with a Bi/(Bi + Te) mole ratio of 0.5 exhibited a Seebeck coefficient of −51.6 μV/K and a power factor of 7.1 × 10−4 W/K2 · m. The p-type Sb-Te film electroplated at 20 mV in a 70 mM solution with an Sb/(Sb + Te) mole ratio of 0.9 exhibited a Seebeck coefficient of 52.1 μV/K and a power factor of 1.7 × 10−4 W/K2 · m. A thermopile sensor composed of 196 pairs of the p-type Sb-Te and the n-type Bi-Te thin-film legs exhibited sensitivity of 7.3 mV/K.  相似文献   

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