变价稀土元素Eu掺杂BiCuSeO热电性能的研究

作为一种适于中温下使用的极具发展前景的新型热电材料,BiCuSeO由于本征热导率低且Seebeck系数较高而广受关注。本研究探索了变价稀土元素Eu替换Bi位对BiCuSeO热电材料微观组织和热电性能的影响。实验结果显示,样品中同时存在Eu²⁺和Eu³⁺两种价态的离子,掺杂Eu元素不仅可以增加样品的载流子浓度,还可以调整样品的能带结构,进而改善样品的电输运性能, Bi_0.85Eu_0.15CuSeO电导率显著提升,在823K时达到了98S·cm^–1,相比于未掺杂样品提升了将近6倍。在温度为823K时,Bi_0.975Eu_0.025CuSeO的功率因子可达0.32mW·m^–1·K–2,ZT值为0.49。本研究表明,掺杂变价稀土元素可以有效改善BiCuSeO热电材料的性能。     

温差发电用BiCuSeO基热电材料的研究进展

BiCuSeO基热电材料由于具有较低的热导率和较高的Seebeck系数,热电性能优异,且原料储藏丰富、价格低廉、安全无毒,被认为是一种具有潜在应用前景的新型热电转换材料。首先介绍了BiCuSeO基材料的晶体结构、电子结构、热电性能等基本特征,随后综述了近年来国内外关于BiCuSeO基热电材料的研究进展,评述了提高其热电性能的手段,包括Na、Ag、Mg、Ca、Sr、Ba等低价元素掺杂,铜空位,双空位,带隙调整,晶粒细化,织构化和调制掺杂等。通过电热输运特性的协同调控,可使其ZT值从未掺杂样品的0.4左右提高到1.5。最后从实际应用的角度出发提出了今后BiCuSeO基热电材料的研究方向及研究重点。     

异层等价离子双掺杂策略优化BiCuSeO的热电性能

选取BiCuSeO双亚层超晶格热电材料为研究对象, 通过La、Ag单掺杂和双掺杂两种方式等价取代[Bi₂O₂]²⁺亚层和[Cu₂Se₂]^2-亚层中的Bi、Cu位点, 并对其热电输运性能和缺陷调控机理进行研究, 结果发现：La-Ag双掺杂可以结合两种单掺杂的优势, 在适度提升载流子浓度的同时保持与纯样相当的载流子迁移率, 从而使电导率得到大幅度的提升。与此同时, La-Ag双掺杂可以引发能带收敛效应, 有助于同步获得较高的载流子迁移率和Seebeck系数, 最终使PF得到了优化; 另一方面, 由于点缺陷对载热声子的强烈散射作用, 样品的晶格热导率和总热导率进一步降低, 使最终ZT值也得到了优化。结果, La-Ag双掺杂样品的ZT值在755 K下达到0.46, 高于原始纯样(ZT=0.27)和单掺杂样品。该项研究表明La、Ag异层等价双掺杂策略可以实现BiCuSeO热电输运参数的协同调控与优化。     

高度织构NaCo2O4陶瓷的热电性能研究

结合固相反应法和冷高压成型技术制备了具有高度结晶各向异性的热电氧化物陶瓷NaCo2O4．X射线衍射和扫描电子显微镜测试表明冷高压压制成型后烧结有利于样品内层状晶粒的C轴沿着施压方向取向排列，形成高度织构．室温以下热电性质的测试表明，电阻率P和Seebeck系数S呈现出金属性，S〉0，属于p型热电材料．与其他方法制备的样品进行比较，虽然晶界或点缺陷对声子散射的减少导致上述样品的热导率偏高，但是由于ρ降低、S升高，使得热电品质因子ZT值提高，300K时ZT值达到0．013．     

聚对苯撑纳米复合提升ZnO基热电材料性能

以溶胶-凝胶法合成了PPP@Zn_1-xCo_xO纳米复合热电材料(x=0, 0.025), 再以放电等离子烧结制备成块体, 并对其热电性能进行了研究。由透射电镜照片发现, PPP纳米颗粒尺寸在200 nm以下。热电性能分析表明, 随着PPP添加量的增加, 赛贝克系数先增大后减小。电导率随PPP含量增加而大幅度提高。与ZnO块体材料相比, 溶胶-凝胶法合成的PPP@Zn_1-xCo_xO纳米复合热电材料的热导率大幅度降低, 在640 K时, 9wt% PPP的纳米复合热电材料热导率降低至5.4 W/(m·K)。电导率的增加和热导率的降低, 导致热电性能大幅度提高, 9wt%PPP@Zn_0.975Co_0.025O纳米复合热电材料在870 K时具有最大ZT值(0.16), 是Zn_0.975Co_0.025O材料的8倍。     

NiO基氧化物热电材料的合成及其性能

采用溶胶凝胶法制备了Li掺杂的NiO基氧化物热电材料,研究了Li掺杂对其热电性能的影响,实验结果表明:在x=0.03,0.06,0.09掺杂比例范围,Li+很好地进入了NiO的晶格,没有形成新的杂相。热电性能测试结果显示,在室温至750K的范围内随着Li掺杂量的增加,电导率显著增加,而样品的Seebeck系数随着掺杂浓度增高明显降低,样品Ni0.94Li0.06O在750K的功率因子PF=1.9×10-5 W.m-1.K-2,随温度升高,PF增加趋势明显,表明在高温环境中可具有更大的PF。     

水热合成BiCl3/Bi2S3复合材料的热电性能

采用水热合成法制备了由纳米棒组成的微米级球形Bi₂S₃颗粒, 然后通过放电等离子烧结技术(SPS)将不同摩尔比例的BiCl₃/Bi₂S₃复合粉末制备成块体。加入适量的BiCl₃不仅提高了Bi₂S₃样品的导电率, 而且降低了其热导率。Bi₂S₃复合0.5mol%BiCl₃的样品在762 K电导率最大, 达到45.1 S·cm^-1, 远高于此温度下纯Bi₂S₃样品的电导率(12.9 S·cm^-1)。Bi₂S₃复合0.25mol% BiCl₃的样品在762 K时热导率最低, 为0.31 W·m^-1·K^-1, 低于同一温度下纯Bi₂S₃的0.47 W·m^-1·K^-1。在762 K下, Bi₂S₃复合0.25mol% BiCl₃的样品获得最大ZT值(0.63), 比纯Bi₂S₃样品(0.22)提高了大约2倍。     

Revealing the Enhanced Thermoelectric Properties of Controllably Doped Donor-Acceptor Copolymer: The Impact of Regioregularity

Albeit considerable attention to the fast-developing organic thermoelectric (OTE) materials due to their flexibility and non-toxic features, it is still challenging to design an OTE polymer with superior thermoelectric properties. In this work, two “isomorphic” donor–acceptor (D–A) conjugated polymers are studied as the semiconductor in OTE devices, revealing for the first time the internal mechanism of regioregularity on thermoelectric performances in D–A type polymers. A higher molecular structure regularity can lead to higher crystalline order and mobility, higher doping efficiency, order of energy state, and thermoelectric (TE) performance. As a result, the regioregular P2F exhibits a maximum power factor (PF) of up to 113.27 µW m⁻¹ K⁻², more than three times that of the regiorandom PRF (35.35 µW m⁻¹ K⁻²). However, the regular backbone also implies lower miscibility with a dopant, negatively affecting TE performance. Therefore, the trade-off between doping efficiency and miscibility plays a vital role in OTE materials, and this work sheds light on the molecular design strategy of OTE polymers with state-of-the-art performances.     

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。     

Thermoelectric properties of solution-synthesized n-type Bi<Subscript>2</Subscript>Te<Subscript>3</Subscript> nanocomposites modulated by Se: An experimental and theoretical study

We report the investigation of the thermoelectric properties of large-scale solution-synthesized Bi2Te3 nanocomposites prepared from nanowires hotpressed into bulk pellets. A third element, Se, is introduced to tune the carrier concentration of the nanocomposites. Due to the Se doping, the thermoelectric figure of merit (ZT) of the nanocomposites is significantly enhanced due to the increased power factor and reduced thermal conductivity. We also find that thermal transport in our hot-pressed pellets is anisotropic, which results in different thermal conductivities along the in-plane and cross-plane directions. Theoretical calculations for both electronic and thermal transport are carried out to establish fundamental understanding of the material system and provide directions for further ZT optimization with adjustments to carrier concentration and mobility.

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新型半导体材料BaSi2的结构及其热电性能的研究

正交相的BaSi2是一种新型半导体材料,具有较小的热传导系数、较大的光学吸收系数和适合的带隙值,是一种潜在的热电材料和理想太阳能电池材料,有着广阔的应用前号。文章介绍了正交相BaSi2晶体结构、电学特性,综述了近年来对其热电性质的研究状况,并就当前BaSi2究中存在的问题和研究动向做了简要讨论。     

半导体纳米薄膜热电性能表征技术的研究进展

综述了半导体纳米薄膜热电性能表征的方法及相关的技术原理.从平行膜面和垂直膜面两方面对纳米薄膜材料热电性能3种重要参数的表征方法进行了描述;同时简要介绍了能直接测量热电优值的Harman方法的基本原理和操作过程.在此基础上指出了各方法的优缺点,并提出了今后开发检测装置需努力的方向.     

Ag掺杂SnSe化合物的制备及热电性能

SnSe是一种潜在的极具应用前景的热电材料。采用机械合金化结合放电等离子烧结的方法制备了Ag掺杂的Sn_1-xAg_xSe (0.005≤x≤0.03)多晶块体热电材料, 并借助XRD、SEM、电热输运测试系统研究了其物相组成、微结构与电热输运性能。XRD分析结果表明, 少量Ag(0.005≤x≤0.01)掺杂仍然能够成功制备出单相斜方结构SnSe化合物, 但随着Ag掺杂量的增加, 基体中出现SnAgSe₂第二相, 且第二相含量逐渐增加。掺杂Ag大幅度提高了载流子浓度, 从而使材料的综合电输运性能(功率因子)显著提高, 当Ag掺杂量x=0.02时, 功率因子提高至4.95×10^-4 W/(m·K²), 较未掺杂SnSe样品提高了36%。尽管掺杂样品的热导率均有小幅升高, 无量纲热电优值(ZT)仍获得一定改善。当Ag掺杂量x=0.02时, Sn_0.98Ag_0.02Se成分样品具有较高的热电优值, 并在823 K附近达到最高值0.82。     

Nanomaterial‐Based Plasmon‐Enhanced Infrared Spectroscopy

Surface‐enhanced infrared absorption (SEIRA) has attracted increasing attention due to the potential of infrared spectroscopy in applications such as molecular trace sensing of solids, polymers, and proteins, specifically fueled by recent substantial developments in infrared plasmonic materials and engineered nanostructures. Here, the significant progress achieved in the past decades is reviewed, along with the current state of the art of SEIRA. In particular, the plasmonic properties of a variety of nanomaterials are discussed (e.g., metals, semiconductors, and graphene) along with their use in the design of efficient SEIRA configurations. To conclude, perspectives on potential applications, including single‐molecule detection and in vivo bioassays, are presented.