Ag纳米线掺杂单晶SnSe热电和力学性能的研究

为探究Ag纳米线掺杂对单晶SnSe的热电和力学性能的影响,建立了一种1D-3D的复合结构体系的理论模型。基于密度泛函理论的第一性原理,计算了Ag纳米线掺杂体系的能带、态密度、载流子相对质量、声子群速度及弹性常数等。从微观特征变化研究Ag纳米线掺杂对热电转化性能和力学性能的影响。结果表明：随着Ag纳米线掺杂浓度的增大,体系的禁带宽度逐渐减小,导带有明显的提高,提高了载流子的迁移率,有利于电导率的提高;载流子相对质量呈现先上升后下降的变化趋势,且相较于未掺杂的SnSe有明显增大,材料的塞贝克系数显著提高;声子群速度逐渐减小,导热性能降低,有利于热电性能的提高;掺杂Ag纳米线的SnSe的体模量和剪切模量均比未掺杂的SnSe小,材料的可塑性和韧性逐渐加强,SnSe的力学性能得到改善。     

基于第一性原理的单层SnSe2二维薄膜的气敏效应

为探索SnSe2二维薄膜材料的气敏特性,采用分子力场方法系统地研究了SnSe2二维单层材料对H2,CO,NH3及NO2等4种典型气体分子的最优吸附位置和吸附能力,并基于密度泛函理论(DFT)的第一性原理方法计算了吸附前后的键长键角变化率、能带结构、态密度及电荷差分密度等参数,分析了吸附前后的电子结构变化与气敏效应之间的内在关联。计算结果发现,吸附H2和CO未能对SnSe2单层的能带结构和电子结构产生改变,而NO2和NH3却在导带底(CBM)和价带顶(VBM)之间分别产生了新的杂质能级,并使费米能级发生位移,从而改变SnSe2单层电子结构。电荷差分密度分析进一步表明SnSe2二维单层未能对H2和CO产生响应,而对NH3和NO2却有明显的气敏效应,其中对NO2有良好的敏感性能和选择性。     

提高热电优值的途径和方法研究

如何调节热电功率、电导率和热导率以实现热电优值(ZT值)的大幅增加一直是个尚未有效解决的研究课题。介绍了通过提高功率因子和降低热导率这两种途径来提高热电材料的热电优值的方法,阐述了有关热电材料的一些重要理念以及影响热电性能的因素。     

碲化铋热电材料掺杂研究进展

碲化铋(Bi₂Te₃)作为近室温区热电性能最好的材料之一,在电子器件、航空航天等领域具有广阔的应用前景。但该材料热电转换效率较低,制约了其规模化工业应用。因此,如何提高Bi₂Te₃材料的热电转换效率成为重点关注的问题。在Bi₂Te₃材料中掺杂不同的元素或第二相,通过调整材料的晶体结构、化学组分及能带结构,调控载流子浓度和迁移率,降低热导率,可提高材料的热电性能。依据Bi₂Te₃热电材料的结构、性质及掺杂改性原理,以掺杂元素或第二相种类和数量作为切入点,总结了目前的部分研究成果,探讨掺杂对Bi₂Te₃材料热电性能的影响,并指出了今后的研究重点及方向。     

热电材料的研究进展

随着热电材料与薄膜制备技术和性能研究手段的发展,具有高热电性能的热电薄膜和低维结构受到人们关注。目前,国内外研究主要集中在如何提高热电材料的能量转换率等核心技术问题上。介绍了热电材料的理论背景、材料分类、制备手段和热电性质的表征,其中,制备手段及热电性质表征主要以Bi2Te3基热电材料展开论述。最后,对热电材料的发展和未来研究方向进行总结。     

Zintl结构化学在热电材料研究中的应用

Zintl相化合物满足“电子晶体-声子玻璃”特征,能够通过化学掺杂和结构修饰来提高其热电性能,是理想的热电材料研究对象。阐明了热电材料性能优化的Zintl结构化学原理,介绍了Zintl结构化学在高性能热电材料研究中的应用,指出利用Zintl结构化学原理寻找高性能热电材料是今后热电材料研究的重要方向。     

Bi2Te3热电材料研究现状

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。     

SnSe薄膜的两步法制备与光电性能研究

采用电子束蒸镀预制层,再对预制层进行硒化的两步法工艺,通过调节硒化温度和退火时间,在玻璃基底上成功制备了SnSe薄膜。利用X射线衍射、拉曼光谱、扫描电子显微镜、紫外可见近红外分光光度计等研究了SnSe薄膜的物相、微观形貌和光学性能。结果表明,在450℃下硒化退火60min可制备出纯相的多晶SnSe薄膜,其带隙为0.93eV。在功率为200mW/cm²的980nm激光照射下,对SnSe薄膜进行了光电响应特性测试,通过曲线模拟得出所制薄膜的响应时间和恢复时间分别为62和80ms。     

热电制冷技术的研究进展北大核心

热电制冷（TEC）已成为制冷领域的一个重要发展方向,但是由于其转换效率过低且材料成本较高,目前难以得到广泛应用。对热电制冷技术进行了简要介绍,并综述了热电制冷技术的研究进展,包括热电材料、结构优化和散热方式。讨论并分析了有机热电材料和无机热电材料的热电性能、不同结构设计所导致的性能系数、不同散热方式对制冷效率的影响。最后,对热电制冷技术的优化进行了简单总结,只有不断提高热电材料的优值系数,并选择合适的结构设计和散热方式,才能使热电制冷技术在各个领域拥有更大的发展空间。     

热电材料最新论文摘录

☆热电材料的研究现状及展望【作者】刘杨【机构】哈尔滨师范大学物理与电子工程学院【摘要】本文综述了不同种类热电材料的结构特征和热电性能。归纳了提高热电材料的热电性能的方法、途径以及热电材料     

Nanoscale Organic Thermoelectric Materials: Measurement,Theoretical Models,and Optimization Strategies

The demands for waste heat energy recovery from industrial production, solar energy, and electronic devices have resulted in increasing attention being focused on thermoelectric materials. Over the past two decades, significant progress is achieved in inorganic thermoelectric materials. In addition, with the proliferation of wireless mobile devices, economical, efficient, lightweight, and bio‐friendly organic thermoelectric (OTE) materials have gradually become promising candidates for thermoelectric devices used in room‐temperature environments. With the development of experimental measurement techniques, the manufacturing for nanoscale thermoelectric devices has become possible. A large number of studies have demonstrated the excellent performance of nanoscale thermoelectric devices, and further improvement of their thermoelectric conversion efficiency is expected to have a significant impact on global energy consumption. Here, the development of experimental measurement methods, theoretical models, and performance modulation for nanoscale OTE materials are summarized. Suggestions and prospects for the future development of these devices are also provided.     

Bi2Te3热电材料改性研究及其进展

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。     

Understanding of the Extremely Low Thermal Conductivity in High‐Performance Polycrystalline SnSe through Potassium Doping

P‐type polycrystalline SnSe and K_0.01Sn_0.99Se are prepared by combining mechanical alloying (MA) and spark plasma sintering (SPS). The highest ZT of ≈0.65 is obtained at 773 K for undoped SnSe by optimizing the MA time. To enhance the electrical transport properties of SnSe, K is selected as an effective dopant. It is found that the maximal power factor can be enhanced significantly from ≈280 μW m^?1 K^?2 for undoped SnSe to ≈350 μW m^?1 K^?2 for K‐doped SnSe. It is also observed that the thermal conductivity of polycrystalline SnSe can be enhanced if the SnSe powders are slightly oxidized. Surprisingly, after K doping, the absence of Sn oxides at grain boundaries and the presence of coherent nanoprecipitates in the SnSe matrix contribute to an impressively low lattice thermal conductivity of ≈0.20 W m^?1 K^?1 at 773 K along the sample section perpendicular to pressing direction of SPS. This extremely low lattice thermal conductivity coupled with the enhanced power factor results in a record high ZT of ≈1.1 at 773 K along this direction in polycrystalline SnSe.     

Re-Doped p-Type Thermoelectric SnSe Polycrystals with Enhanced Power Factor and High ZT > 2

Thermoelectric technology enables the direct interconversion between heat and electricity. SnSe has received increasing interest as a new promising thermoelectric compound due to its exceptionally high performance reported in crystals. SnSe possesses intrinsic low thermal conductivity as a congenital advantage for thermoelectric, but high thermoelectric performance can be hardly achieved due to the difficulty to realize efficient doping to raise its low carrier concentration to an optimal level. In this work, it is found that a series of rare earth elements are effective dopants for SnSe, which can greatly improve the electrical transport properties of p-type polycrystalline SnSe. In particular, the remarkable enhancement in electrical conductivity and power factor is achieved by Na/Er co-doping at 873 K. The lattice thermal conductivity is reduced due to the presence of abundant defects (dislocations, stacking faults, and twin boundaries). Consequently, a peak thermoelectric figure of merit ZT (2.1) as well as a high average ZT (0.77) are achieved in polycrystalline SnSe.     

Thermoelectric Performance for SnSe Hot-Pressed at Different Temperature

Herein, nanoparticles SnSe are prepared by fusion method together with ball-milling technique and the effect of hot-pressing temperatures on the thermoelectric properties of the dense materials is explored. Due to the optimization of carrier concentration, the peak figure of merit (ZT) value of the compacted material reaches 0.73 for SnSe sample hot-pressed at 400°C and 450°C. The present investigation indicates that the thermoelectric performance of the SnSe compound can be significantly improved by sintering with suitable temperature.     

Thermoelectric Properties and Electronic Structure of Bi- and Ag-Doped Mg<Subscript>2</Subscript>Si<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>Ge<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> Compounds

Mg₂Si_1−x Ge _x compounds were prepared from pure elements by melting in tantalum crucibles. The reaction was conducted under an inert gas in a special laboratory setup. Samples for thermoelectric measurements were formed by hot pressing. Structure and phase composition of the obtained materials were investigated by x-ray diffraction (XRD). Morphology and chemical composition were examined by scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS), respectively. Thermoelectric properties, i.e., the Seebeck coefficient, the electrical conductivity, and the thermal conductivity, were measured in the temperature range of 500 K to 900 K. The effect of Bi and Ag doping on the thermoelectric performance of Mg-Si-Ge ternary compounds was investigated. The electronic structures of binary compounds were calculated using the Korringa–Kohn–Rostoker (KKR) method. The effects of disorder, including Ge substitution and Bi or Ag doping, were accounted for in the KKR method with coherent potential approximation calculations. The thermoelectric properties of doped Mg₂Si_1−x Ge _x are discussed with reference to computed density of states as well as the complex energy band structure.     

Double Charge Polarity Switching in Sb-Doped SnSe with Switchable Substitution Sites

Tin mono-selenide (SnSe) is one of the most promising thermoelectric materials; however, it experiences difficulty in controlling the carrier polarity, which is inevitable for realizing p-n homojunction devices. Herein, double switching of charge polarity in (Sn_1−xSb_x)Se by varying x is reported; pure SnSe shows p-type conduction, whereas the polarity of (Sn_1−xSb_x)Se switches to n-type conduction for 0.005 < x < 0.05, and then re-switches to p-type conduction for x > 0.05. The major Sb substitution site switches from the Se (Sb_Se) to Sn site (Sb_Sn) with increasing x. Sb_Sn (Sb³⁺ at Sn²⁺) works as a donor, but Sb_Se (Sb³⁻ at Se²⁻) does not produce a hole because of the Sb–Sb dimer formation. The mechanism of double polarity switching is explained by native p-type conduction in pure SnSe due to Sn-vacancy formation, whereas (Sn_1−xSb_x)Se exhibits n-type behavior due to conduction through the Sb_Se impurity band formed above the valence band maximum, and finally re-switches to weak p-type, where the Fermi level approaches the midgap level between the Sb_Se band and conduction band minimum. Clarification of the Sb doping mechanism will provide a crucial guide for developing more sophisticated doping routes for SnSe and high-performance energy-related devices.     

Point Defect Engineering of High‐Performance Bismuth‐Telluride‐Based Thermoelectric Materials

Developing high‐performance thermoelectric materials is one of the crucial aspects for direct thermal‐to‐electric energy conversion. Herein, atomic scale point defect engineering is introduced as a new strategy to simultaneously optimize the electrical properties and lattice thermal conductivity of thermoelectric materials, and (Bi,Sb)₂(Te,Se)₃ thermoelectric solid solutions are selected as a paradigm to demonstrate the applicability of this new approach. Intrinsic point defects play an important role in enhancing the thermoelectric properties. Antisite defects and donor‐like effects are engineered in this system by tuning the formation energy of point defects and hot deformation. As a result, a record value of the figure of merit ZT of ≈1.2 at 445 K is obtained for n‐type polycrystalline Bi₂Te_2.3Se_0.7 alloys, and a high ZT value of ≈1.3 at 380 K is achieved for p‐type polycrystalline Bi_0.3Sb_1.7Te₃ alloys, both values being higher than those of commercial zone‐melted ingots. These results demonstrate the promise of point defect engineering as a new strategy to optimize thermoelectric properties.     

Effects of doping on the high-temperature thermoelectric properties of IrSb3 skutterudite compounds

The IrSb₃-based skutterudite compounds have a potential for thermoelectric applications because of high Hall mobility, Seebeck coefficient, and relatively low thermal conductivity. In the present study, polycrystalline p- and n-type IrSb₃ compounds are prepared by powder metallurgy techniques. The effect of doping on thermoelectric properties has been investigated in binary and ternary IrSb₃ compounds using Ru, Ge, Pd, or Pt as a dopant. It is shown that the electrical properties depend strongly not only on the kinds of doping impurities but also their levels. Our theoretical analysis suggests that the effective mass is significantly affected by doping impurities and the levels.