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摘要近年来， 纳米尺寸范围内的材料在科研和现代技术的应用吸引了科学家们的极大兴趣。随着材料的尺度减小到纳米尺寸范围内，其光学、电学、以及热力学性质等都与大块尺寸材料明显不同。这是由于纳米材料尺寸小，表面/体积比大，表面处原子聚集，使得表面原子产生配位缺陷而导致的性质差异。在上述提到的所有性质中，纳米材料的热力学性质显得尤为重要。 用理论方法来描述相应的热力学性质是一项非常伟大而又有实际意义的工作，这不仅可以加深我们对纳米材料的理解，还可以引导实验操作制备及拓展它们在不同领域中的应用。基于尺寸相关的内聚能模型并结合相应的热力学理论， 初步建立金属超导纳米晶体的热力学模型来描述材料的临界转变温度 Tc(D)随着晶粒尺寸D 的变化规律。在这个模型中，超导纳米晶体的临界转变温度对尺寸具有一定的依赖性，Tc(D)取决于 D的大小和相关的临界条件。对于各种自由纳米颗粒、纳米线或薄膜，通过模型得到的所有预测结果与实验结果相一致。由此可见，模型的建立是理论研究与实验结果之间不可缺少的一座桥梁。58612
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毕业论文关键词:纳米材料；超导温度；临界转变温度；热力学模型
Abstract In recent years, nano-sized materials science research and application of moderntechnology has attracted great interest to scientists. When the material is reduced to thenanometer scale size range class, optical, electrical, magnetic and thermodynamicproperties are different from the chunk size, and the difference is not small. This is becausethe small size of nano materials, surface / volume ratio, surface atomic aggregationproperties of surface atoms caused by differences in the coordination of defects. In all theproperties mentioned above, the thermodynamic properties of the nanocrystals isparticularly important. The method described by the theory of thermodynamic properties isa very great and meaningful work, not only to deepen our understanding of the nature ofthe nanocrystals can also guide the preparation of test operation and expand theirapplications in different fields.Based on a size-dependent cohesive energy model and combined with thecorresponding thermodynamic theory, the initial establishment of the superconductingmetal nanocrystals thermodynamic model to describe the critical transition temperatureTc(D) of the material as the variation of the grain size D. In this model, the criticaltransition temperature of superconducting nanocrystals is dependent on the size, Tc(D)depends on the D and the critical conditions. All the predicted results of the model areconsistent with the experimental results for a variety of free nanoparticles, nanowires orfilms. It can be seen that the establishment of the model is an indispensable bridge betweentheory and experiment.
Keywords: nanocrystalline materials; superconducting temperature ;critical transitiontemperature ;Thermodynamic model
目录
第一章 绪论 1
1.1选题的目的及意义. 1
1.1.1 选题的目的.. 1
1.1.2 选题的意义.. 1
1.1.3 本课题主要研究方法 2
1.2 研究背景2
1.2.1 纳米材料的结构与特性. 2
1.2.2 纳米材料的合成方法.. 4
1.2.3 纳米材料的应用..6
1.2.4 纳米材料基本特征.8
1.3 超导温度10
1.3.1 超导温度的概念10
1.3.2 超导材料的研究现状及应用10
1.3.3 超导材料的前景展望 11
1.4 本课题主要工作内容11
第二章 金属纳米晶体超导温度的热力学研究. 12
2.1引言 12
2.2 理论模型13
2.3 结果与讨论..14
2.4 小结.. 17
总结.18
致谢 19
参考文献.20