【作者】 杨秀丽；

【导师】 唐新峰；

【作者基本信息】 武汉理工大学 ， 材料学， 2006， 硕士

【摘要】 本论文首先用固相反应分别制备了Ni_xCo_4-xSb₁₂（x=0.1,0.2,0.4）和Ba_yNi_xCo_4-xSb₁₂（y=0.16～0.35,x=0.1～1.0）,用放电等离子烧结制成致密的块体材料。在对均质材料Bi₂Te₃和Ba_yNi_xCo_4-xSb₁₂热电传输特性研究的基础上,对梯度结构热电材料Bi₂Te₃/Ba_0.35Ni_0.1Co_3.9Sb₁₂的界面温度进行了优化,对梯度结构热电材料当中均质材料Bi₂Te₃和Ba_0.35Ni_0.1Co_3.9Sb₁₂的长度进行了优化设计。通过两步放电等离子烧结的方法制备出了梯度结构热电材料Bi₂Te₃/Ba_0.35Ni_0.1Co_3.9Sb₁₂;研究了梯度结构n型Bi₂Te₃/Ba_0.35Ni_0.1Co_3.9Sb₁₂热电材料的热电性能。 获得的主要研究结果如下: 1.对Ni_xCo_4-xSb₁₂（x=0.1,0.2,0.4）的热电性能及传输性能进行优化,其中Ni_0.4Co_3.6Sb₁₂试样在800K时性能优值ZT值达到最大0.48。 2.对Ba_yNi_xCo_4-xSb₁₂（y=0～0.4,x=0.1～1.0）的热电性能及传输性能进行优化,其中Ba_0.35Ni_0.1Co_3.9Sb₁₂试样在800K时性能优值ZT值达到最大0.56。 3.根据两种均质材料Bi₂Te₃和Ba_0.35Ni_0.1Co_3.9Sb₁₂热电性能优值与温度的关系,对梯度结构n-Bi₂Te₃/Ba_0.35Ni_0.1Co_3.9Sb₁₂热电材料界面温度进行了优化,得出梯度结构Bi₂Te₃/Ba_0.35Ni_0.1Co_3.9Sb₁₂热电材料最佳的界面温度约为630K。 4.以两种均质材料Bi₂Te₃和Ba_0.35Ni_0.1Co_3.9Sb₁₂的导热特性为依据,对在宽温域内使用的梯度结构Bi₂Te₃/Ba_0.35Ni_0.1Co_3.9Sb₁₂热电材料中均质材料的长度进行了理论设计,得出在300K～800K的温度范围内,均质材料Bi₂Te₃和Ba_0.35Ni_0.1Co_3.9Sb₁₂最佳的长度比为5.5:10。 5.在以Pd作为界面材料和不用界面材料的情况下,采用两步放电等离子烧结方法制备出了梯度结构Bi₂Te₃/Ba_0.35Ni_0.1Co_3.9Sb₁₂热电材料。SEM的分析结果表明:n-Bi₂Te₃/Ba_0.35Ni_0.1Co_3.9Sb₁₂梯度结构在界面处结合良好,扩散现象不严重,而n-Bi₂Te₃/Pd/Ba_0.35Ni_0.1Co_3.9Sb₁₂梯度结构在界面处结合不理想,说明所选界面材料不是最佳材料。 6.建立模型计算了梯度结构n型Bi₂Te₃/Ba_0.35Ni_0.1Co_3.9Sb₁₂热电材料的内阻、平均Seebeck系数、输出功率等,结果表明:在较宽的温度范围内,相比较于均质材料Bi₂Te₃和Ba_0.35Ni_0.1Co_3.9Sb₁₂,梯度结构n型更多还原

【Abstract】 In this paper, firstly, filled skutterudite compounds Ba_yNi_xCo_4-xSb₁₂ are prepared by solid reaction. The compact blocks are obtained by Sparkle Plasma Sintering （SPS）. The junction temperature of graded Bi₂Te₃/Ba_0.35Ni_0.1Co_3.9Sb₁₂ thermoelectric material was optimized based on the thermoelectric transport properties of monolithic materials, also the length ratio of monolithic materials Bi₂Te₃ and Ba_0.35Ni_0.1Co_3.9Sb₁₂ were optimized in theory when graded materials were used in the temperature difference ranging from 300K to 800K. The n-type graded Bi₂Te₃/Ba_0.35Ni_0.1Co_3.9Sb₁₂ thermoelectric material was prepared by two-step SPS, and the thermoelectric properties of the n-type graded Bi₂Te₃/Ba_0.35Ni_0.1Co_3.9Sb₁₂ thermoelectric material were investigated.Some conclusions have been drawn in the present work as follows:1. The thermoelectric properties and the transport properties of the compounds Ni_xCo_4-xSb₁₂ were optimized, and the greatest dimensionless thermoelectric figure of merit value of 0.48 was obtained at 800K for the compound Ni_0.4Co_3.6Sb₁₂.2. The thermoelectric properties and the transport properties of the compounds Ba_yNi_xCo_4-xSb₁₂ were optimized, and the greatest dimensionless thermoelectric figure of merit value of 0.56 was obtained at 800K for the compoundBa_0.35Ni_0.1Co_3.9Sb_12.3. The junction temperature optimized by the relationship between figure-of-merits of monolithic materials and temperature is about 630K.4. According to the thermal properties of monolithic materials Bi₂Te₃ and Ba_0.35Ni_0.1Co_3.9Sb₁₂, the optimized result is that the optimal length ratio of Bi₂Te₃ and Ba_0.35Ni_0.1Co_3.9Sb₁₂ is about 5.5:10 when it was used in the temperature difference from 300K to 800K.5. The graded Bi₂Te₃/Ba_0.35Ni_0.1Co_3.9Sb₁₂ and Bi₂Te₃/Pd/Ba_0.35Ni_0.1Co_3.9Sb₁₂ thermoelectric material was prepared by two-step SPS. The analysis result of the SEM revealed that junction appearance of the graded Bi₂Te₃/Ba_0.35Ni_0.1Co_3.9Sb₁₂ thermoelectric material is excellent, but Bi2Te3/Pd/Bao.35Nio.iCo3.9Sbi2 is bad, which show Pd is not the optical material.6. The internal resistance, average Seebeck coefficient and power output were calculated by theory model. We finded that the average Seebeck coefficient of graded material possess higher values over a wide temperature difference, and the calculated maximum power outputs of graded material is about 22mW when the loaded is fixed at 0.1Ω, which is about 1.8 times than that of Ba_0.35Ni_0.1Co_3.9Sb₁₂ compound（12mW）.更多还原