【作者】 齐鸣；

【导师】 柯学志；

【作者基本信息】 华东师范大学 ， 理论物理， 2012， 硕士

【摘要】 在当今世界,随着一些重要的不可再生燃料如天然气和石油的急剧减少和其使用带来的诸多环境问题,能源问题一直是人们关注的焦点。为了解决基本的能源问题并维持可持续发展,人们一直在寻找新形式的能源以满足对能源迅速提高的需要和环境的保护。本文所研究的热电材料是一种新型的功能材料,它通过固体中载流子运输实现热能和电能转换,所以热电材料可以被广泛运用到很多领域内的发电装置和制冷设备中。据报道,目前热电设备的转换效率只有10%左右,而一般热机的发电效率都能达到35%。由于热电材料的转换效率较低,这极大的限制了热电材料在现在领域和更多领域的进一步深入应用。从理论角度看,在从热力学基本定律出发对热电材料所进行的理论基础研究中,并未发现热电材料的热电优值上限。所以从理论上来看,尽管目前的热电材料的转换效率还不尽如人意,但是从长远角度看,热电材料有其广泛的开发前景。如果可以开发出ZT值达到3左右的热电材料,传统的制冷和发电方式就可以很大程度上被最新的热电制冷和发电方式所取代。纳米复合材料(PbTe)1-x(AgSbTe2)x(x～0.05)是一种很有潜力的热电材料,在温度800K的时候呈现出非常高的热电效率,它们的热电优值ZT值能达到将近1.7左右。最新的研究表明其微纳团簇结构的出现是其产生高ZT值的关键。所以准确的确定这些极其复杂的纳米复合材料的细微结构,特别是原子排列顺序和原子集结机制是非常有意义的。本文对三种PbTe基热电材料(Na20Pb460Bi20Te500、 Na20Pb460Sb20Te500和Ag20Pb460Bi20Te500计算研究发现：一类材料的结构规律与库伦相互作用势模型所预测的趋势基本一致；另一类由于晶格驰豫作用能量大于库伦相互作用能,其遵循的结构规律与库伦相互作用势模型所预测的趋势刚好相反。更多还原

【Abstract】 Facing the worldwide energy crisis, such as natural gas and oil, environmental pollution which seriously threaten the survival and development of mankind, researchers from all over the world are working at exploring alternatives to fossil energy, In order to solve energy crisis and maintain the sustainable development, human being have been looking for new forms of energy to meet the needs of the rapid increase of energy and environmental protection. Thermoelectric materials in the paper are kind of functional material which can convert heat to electricity directly or reversely, which are prospect using as the thermoelectric generators and cooling devices.However, the thermoelectric material at present has a low conversion efficiency, According to reports, the conversion efficiency of thermoelectric equipment only is10%lower than that of the engine power efficiency, which can achieve35%or so, which confines it greatly from being used extensively in the national economy in turn, the property of thermoelectric material can be measured by the dimensionless figure of merit-ZT, optimal ZT values limit is not found from the perspective of theory. Though the ZT values of the thermoelectric material being studied are low which cannot satisfy the need of practical application, the thermoelectric materials are widely prospect of development in the longer term. If the ZT values of the thermoelectric material being studied are higher than3, the traditional refrigeration and power generation way can be replaced with the latest thermoelectric way.The nanocomposites (PbTe)(1-X)(AgSbTe2)x(x～0.05) exhibit very high TE efficiency measured by the figure of merit parameter ZT～1.7at800K. It has been recently recognized that the presence of nanoprecipitates is likely key to producing high ZT values. A prerequisite to understanding TE properties is an accurate determination of the micro structure of these complex nanocomposites, especially the atomic arrangement and nucleation mechanism. In this paper, studying for three different PbTe-based materials, we find that the structure rule of one kind of material is generally consistent with the prediction of Coulomb interaction potential model. The other one is the other way round, and the reason can be said as the energy caused by lattice relaxation is greater than Coulomb potential energy.更多还原