摘 要

方钴矿化合物MX3(M为金属元素，如Rh,Co或Ir等，X是V族元素，如As，P或Sb等）是一类研究者们青睐的新型中温热电材料。作为热能与电能直接转化的功能材料，方钴矿化合物的的晶格热导率较大，导致了材料的热电性能指数ZT不高。通过近几十年的深入研究，研究者找到了很多能够降低方钴矿化合物晶格热导率的办法，大部分将重点放在了优化材料结构上，例如填充或掺杂。引入纳米孔洞也是近年来提出的一种微结构调控方法，可以在一定程度上提高ZT值。

深入了解锑化钴的力学行为与微观结构的关系对该材料的规模化应用具有重要意义。本文将运用分子动力学软件LAMMPS对含有纳米孔洞的锑化钴热电材料进行微观模拟。LAMMPS是一款开源的分子动力学模拟软件，可供研究人员免费下载使用。

对于含孔洞的锑化钴热电材料的原子模型，所有孔洞均假设为圆形贯穿的，考虑了孔径和孔隙率这两个因素分别变化，构造了两组孔洞模型。建立了含孔洞锑化钴热电材料的分子动力学模拟方法，研究了含孔洞锑化钴热电材料的基本力学性能的影响，本论文中研究300K下的虚拟单轴拉伸实验，获得了相应的应力-应变曲线、杨氏模量、极限强度的基本信息。

研究结果表明，含孔洞锑化钴的力学性能虽然比理想单晶模型差很多，但相对其他热电材料来说其力学性能仍然是较好的。从规律上说，杨氏模量受孔隙率影响，孔隙率越大，杨氏模量越低，但其降低的幅度不大；而极限强度对材料的微结构非常敏感，它随孔径增加而明显降低。

关键词：方钴矿化合物，热电材料，分子动力学，力学性能，单轴拉伸

Abstract

Skutterudite compound MX3 (M is a metal element, such as Rh, Co or Ir, etc.,X is a element of group V,such as As, P, Sb, etc.) as a new type of electrically conductive material received widespread warmed attention and study.As a direct conversion of thermal energy and electrical energy functional materials,Skutterudite has larger lattice thermal conductivity,resulting in the performance index ZT of thermoelectric materials is not high.Through in depth research in recent decades,the researchers found a number of compounds that could reduce Skutterudite lattice thermal conductivity approach,most of them focus on optimizing the structure of the material,for example, filled or doped.The introduction of nano-holes are also proposed in recent years to a micro structural control method,ZT value can be increased to some extent by the way.

It is great important of depth understanding of the relationship between the mechanical behavior of CoSb3 and microstructures for the large-scale application of the material.This article will use molecular dynamics software LAMMPS to microscopic simulate the thermoelectric material CoSb3 containing nano-holes.LAMMPS is an open source molecular dynamics simulation software, available for researchers free download.

We established a molecular dynamics simulation of the thermoelectric materials CoSb3 containing holes and researched the influence of basic mechanical properties of the thermoelectric materials CoSb3 containing holes,including virtual uniaxial tension and uniaxial compressive mechanical experiments in normal temperature.We also obtained the corresponding basic information of stress - strain curve, Young's modulus, ultimate strength, special structural evolution.

Research indicates that though the mechanical properties of CoSb3 containing holes is much worse than the ideal model of a single crystal,but it’s still preferred relative to other thermoelectric materials.From the law,Young's modulus is affected by porosity,the larger the porosity, the lower the young's modulus,but the decrease is not very large.The ultimate strength of the material is very sensitive to microstructure,it decreases with the increase of the pore size.

Key Words：Skutterudite compound；Thermoelectric materials；Molecular dynamics；Mechanical properties;Uniaxial stretching

目 录

第1章 绪论 1

1.1 热电材料的研究进展 1

1.2 分子动力学模拟的原理 3

1.3 本文的研究目标与研究内容 5

第2章 含孔洞CoSb3的分子动力学模型 6

2.1 CoSb3晶体结构和作用势 6

2.2 Materials studio的应用 7

2.3 利用VC6.0建立孔洞模型 9

第3章 300K下含孔洞CoSb3的单轴拉伸模拟 13

3.1 模拟过程 13

3.2 驰豫结果 13

3.3 孔洞对拉伸力学性能的影响 14

3.2.1 孔隙率变化，孔径不变 14

3.2.2 孔隙率不变，孔径变化 16

第4章 结论与展望 18

参考文献 19

致 谢 20