应力致石墨烯类二维晶体奇异形变/相变特征及其机制研究

项目名称： 应力致石墨烯类二维晶体奇异形变/相变特征及其机制研究

项目编号： No.51271139

项目类型： 面上项目

立项/批准年度： 2013

项目学科： 一般工业技术

项目作者： 马飞

作者单位： 西安交通大学

项目金额： 80万元

中文摘要： 石墨烯类二维晶体使用时通常要依附于异质基体表面，因热失配、结构失配或外载而引入的应力是此类超薄器件安全可靠服役的致命问题。本项目针对这种超薄二维体系，拟结合静力学分析和分子动力学模拟，考察因化学键旋转与断裂竞比可能引发的有别于传统三维晶体的应力致形变/相变行为；研究不同温度和外载条件下Stone-Wales(SW)拓扑缺陷的动态演化过程，揭示其脆性-塑性变形转变的热/动力学诱因，形成对二维晶体形变/相变机制及其制约因素的普适性认识；参照分子动力学模拟所观察到的特征变形结构，计算相对应的晶格振动声子谱和电子能带结构，建立特征形变/相变结构与Raman光谱特征峰和扫描隧道谱（STS）之间的"指纹"识别关系，发展和完善二维晶体形变/相变行为的实验表征方法；结合微拉伸加载过程的Raman光谱和STS表征及后续HRTEM观察，对理论模拟结果予以验证，为未来纳米电子器件的原理设计提供物理参照。

中文关键词： 石墨烯；形变；相变；应力；可靠性

英文摘要： For graphene-like two-dimensional crystals with planar structure of only several monolayers in thickness, they should be attached onto some heterogeneous substrates, such as, silicon covered with hafnium dioxide, in practical applications. Stress can not be avoided in such a case due to thermal misfit, structural misfit as well as external loading, which will often induce the structural breakage and even the failure of device function. So it is indeed one of the fateful issues for the reliability and stability of these ultra-thin devices and, should be paid more attention. This proposal will focus on the stress induced anomalous plastic deformation/phase transformation as a result of the competition between bond rotation and fracture, in particular, the behaviors different from those of traditional three-dimensional materials. Based on the statics analysis and molecular dynamics (MD) simulation, we will emphasize on the nucleation, movement, multiplication and annihilation of Stone-Wales (SW) topological defects under different temperature and loading conditions, uncover the relevant thermal and kinetic inducements for brittle-to-plastic transformation, and understand the genaral mechanism and the influencing factors of the plastic deformation/phase transformation in these graphene-like two-dimensional materials

英文关键词： graphene；plastic deformation；phase transformation；stress；reliability