【作者】 曹艳；

【导师】 夏盛清；

【作者基本信息】 山东大学 ， 化学， 2025， 硕士

【摘要】 随着深空探测任务的复杂性及规模的不断提升,对先进能源技术的依赖日益增强。其中,放射性同位素温差热电技术(RTG)作为深空探测任务中不可替代的电源供应方式,其重要性不言而喻。以n型La3-xTe4和p型Yb14MnSb11为代表的新型高温热电因其优异的热电性能和稳定性备受关注。同时,由于此类材料较差的机械性能以及抗氧化性能,严重影响了材料的器件应用能力。针对上述问题,本文以n型La3-xTe4热电材料为研究对象,通过复合金属镍,提升了 n型La3-xTe4的综合应用能力,并初步研究了相应的高温热电器件。本论文开展的主要工作及结果如下:1.通过高能球磨原位分解NiTex前驱体,合成了一系列Ni基复合La3-xTe4材料。通过在在La3-xTe4基体中引入大量的Ni纳米颗粒,不仅显著提升材料的电输运性能,使复合材料的功率因子增加了约64%。同时存在的Ni纳米颗粒也增加声子散射,抑制了晶格热导率。Ni的引入解耦了电输运和热输运性能,最终使热电性能得到大幅度提升。例如,Ni复合含量为13vol.%的样品中获得zTmax～1.6的高热电优值,并在600 K-1073 K温度范围内达到了 zTave～1.1。2.通过复合金属Ni改善了 La3-xTe4材料的机械性能和抗氧化性能。研究发现,La3-xTe4对O2具有高敏感性,在La3-xTe4基体中原位复合Ni大幅度提升了材料的抗氧化性能。并且由于La3-xTe4体系遵循离子键合多晶材料的特性趋势,使材料表现出典型的脆性断裂特征。通过在基体引入大量Ni纳米颗粒,不仅有助于改善材料抗氧化性能,并且均匀分布的Ni纳米颗粒使材料获得了良好的断裂韧性。3.组建了基于p型Yb14MnSb11和n型La3-xTe4基热电材料的高温热电器件。利用SPS实现p型、n型热电臂的串联及冷热端电极的一步连接。通过有限元模拟与实验测试相结合,研究了 La3-xTe4/Yb14MnSb11器件的输出功率与转换效率。模拟单对器件在热端温度为1273 K时,转换效率可达到5.3%。实际测试器件在热端温度958 K时获得142 mV的开路电压和42 mW的输出功率。并且采用复合Ni基n型材料进一步优化器件内阻,可以使输出功率提升20%。更多还原

【Abstract】 As the complexity and scale of deep space exploration missions continue to increase,the reliance on advanced energy technologies is growing.Among them,radioisotope thermoelectric technology(RTG)is an irreplaceable power supply method in deep space exploration missions,and its importance is self-evident.The new high-temperature thermoelectrics,represented by n-type La3-xTe4 and p-type Yb14MnSb11,have attracted much attention due to their excellent thermoelectric properties and stability.At the same time,due to the poor mechanical properties and oxidation resistance of such materials,the device application ability of the materials is seriously affected.In order to solve the above problems,the n-type La3-xTe4 thermoelectric material is taken as the research object,and the comprehensive application ability of n-type La3xTe4 is improved by combining nickel metal,and the corresponding high-temperature thermoelectric device is preliminarily studied.The main work and results of this thesis are as follows:1.A series of Ni-based composite La3-xTe4 materials were synthesized by in-situ decomposition of NiTex precursors by high-energy ball milling.By introducing a large number of Ni nanoparticles into the La3-xTe4 matrix,the electrical transport performance of the material is significantly improved,and the power factor of the composite material is increased by about 64%.The presence of Ni nanoparticles also increases phonon scattering and inhibits lattice thermal conductivity.The introduction of Ni decouples the electrical and thermal transport performance,and ultimately the thermoelectric performance is greatly improved.For example,a sample with a Ni composite content of 13vol.%obtained a high thermoelectric merit of zTmax～1.6 and zTave～1.1 in the temperature range of 600 K-1073 K.2.The mechanical properties and oxidation resistance of La3-xTe4 were improved by clad metal Ni.It is found that La3-xTe4 is highly sensitive to O2,and the in-situ composite Ni in La3xTe4 matrix greatly improves the oxidation resistance of the material.Because the La3-xTe4 system follows the characteristic trend of ionically bonded polycrystalline materials,the materials exhibit typical brittle fracture characteristics.By introducing a large number of Ni nanoparticles into the matrix,it not only helps to improve the oxidation resistance of the material,but also makes the material obtain good fracture toughness due to the uniform distribution of Ni nanoparticles.3.A high-temperature thermoelectric device based on p-type Yb14MnSb11 and n-type La3xTe4-based thermoelectric materials was constructed.SPS is used to realize the series connection of p-type and n-type thermoelectric arms and the one-step connection of cold and hot terminal electrodes.The output power and conversion efficiency of La3-xTe4/Yb14MnSb11 device was studied by combining finite element simulation and experimental tests.The analog single pair device achieves a conversion efficiency of 5.3%at a hot-end temperature of 1273 K.The actual test device obtained an open-circuit voltage of 142 mV and an output power of 42 mW at a hot-end temperature of 958 K.In addition,the use of composite Ni-based n-type materials to further optimize the internal resistance of the device can increase the output power by 20%.更多还原