【作者】 王琳；

【导师】 陈刚；

【作者基本信息】 哈尔滨工业大学 ， 化学工程与技术， 2011， 硕士

【摘要】 AgPb₁₀SbTe₁₂材料是一种极具应用前景的新型热电材料,具有较高的热电性能。目前制备该材料的方法主要是熔融冷却法和机械合金法,这两种制备方法易操作,但同时需要的制备温度较高,并且难于实现对材料尺寸和形貌的控制。而尺寸以及形貌对材料的热电性能有重要的影响,因此选取合适的制备工艺设计并制备具有特定尺寸和形貌的AgPb₁₀SbTe₁₂热电材料,可为进一步地提高该材料的热电性能提供新的途径。本论文采用反应条件温和的水热法和溶剂热法,通过调节实验参数（如碱浓度,溶剂,表面活性剂等）,可控制备了不同尺寸的立方和花状粒子,并利用XRD、FESEM、TEM以及热电性能测试系统等分析测试手段对其微观结构、形貌和热电性能进行了较为系统的研究,探讨了所制备材料的可能生长机制。结合材料热电性能的测试与分析,总结材料形貌、结构和性能之间的关系。实验结果表明,制备的不同尺寸的AgPb₁₀SbTe₁₂立方和花状粒子具有显著的尺寸和形貌依赖的热电性能:AgPb₁₀SbTe₁₂立方粒子的电导率大于花状粒子,相同形貌的样品,尺寸越小,电导率越低;材料都在一定温度范围内经历了从p型半导体向n型半导体的转变;热导率随温度的升高而降低,并且远远小于块体材料的热导率。在此基础上,利用胺辅助溶剂热法制备了AgPb₁₀SbTe₁₂棒状粒子,考察了不同的反应参数（温度,丙酮,甲酰胺和联胺用量等）在生成AgPb₁₀SbTe₁₂棒状粒子中的作用。结合实验数据,提出了生成棒状粒子可能的“原位自牺牲模板”生长机制与化学反应机理。AgPb₁₀SbTe₁₂棒状粒子电学输运性能测试结果表明所制备的AgPb₁₀SbTe₁₂棒状粒子表现出典型的半导体特性,电导率随温度的升高而增加;在测试温度范围内会经历从p型半导体到n型半导体的转变。更多还原

【Abstract】 AgPb_mSbTe_m+2 material is one of the most promising state-of-art thermoelectric materials, and it possesses relatively high thermoelectric properties. So far, the methods for the preparation of AgPb_mSbTe_m+2 materials have been mostly melt cooling method and mechanical alloying method, these two routes are readily to operate, yet high synthetic temperature is necessary and difficult to control the morphologies and sizes of the as-prepared samples. Since the sizes and morphologies have key influence in the thermoelectric properties of the materials, choosing appropriate synthetic route to prepare AgPb_mSbTe_m+2 with specific sizes and morphologies provides a new route for further improving thermoelectric properties.Here in this paper, mild hydrothermal and solvothermal method were chosen to prepare the products. AgPb₁₀SbTe₁₂ nanocubes and flower-like crystals having different sizes were obtained via adjusting experiment parameters （such as, the concentration of alkali, solvent, and surfactant et al.）, and X-Ray Diffraction （XRD）, Field Emission Scanning Electron Microscopy （FESEM）, Transmission Electron Microscopy （TEM）, Energy Dispersive X-ray Spectroscopy （EDX）, and thermoelectric integrated system test were used to systematically characterize the structure, morphology, composition, and thermoelectric properties of the samples, summarizing the relation among morphologies, structure, and properties.Experiment results indicate the as-synthesized AgPb₁₀SbTe₁₂ nanocubes and flower-like crystals with different sizes possess obvious size and shape dependent thermoelectric properties: AgPb₁₀SbTe₁₂ nanocubes present more excellent electrical conductivity compared to flower-like crystals, and the samples having smaller sizes have lower electrical conductivity for the products with the same morphologies; Moreover, the samples all go through the transformation from p-type semiconductor to n-type semiconductor; The thermal conductivities for the as-prepared products all decrease with rising temperature, and thermal conductivities are far more lower than the bulk materials.Based on the above synthesis route, amine-assisted solvothermal method was used to synthesize poly-crystalline AgPb₁₀SbTe₁₂ rods, and investigate the possible roles of different synthetic parameters （such as, acetone, synthetic temperature, formamide and hydrazine et al.） in the formation of AgPb₁₀SbTe₁₂ rods. A possible‘in-situ self-sacrifice template’growth mechanism and chemical reaction mechanism is proposed integrating the experiment results.The transport property results of the AgPb₁₀SbTe₁₂ rods reveal the as-prepared samples display typical semiconductor character, the electrical conductivity increases with the rising temperature; and goes through the conversion from p-type semiconductor to n-type semiconductor like the naocubes and flower-like crystals.更多还原