氮化硼片纳米材料的导热性能及其受力调控机理研究

Hexagonal boron nitride (h-BN) sheet is an excellent micro-nano device and has great application value in high heat flux and thermoelectric materials, because it is an insulation material with high thermal conductivity and its heat transport can be controlled. However, the values of thermal conductivity are quite different according to different experimental and theoretical methods, for which restricts the application and development of the h-BN sheets. The thermal conductivity and strain controlled thermotutability of h-BN sheet are studied by theoretical analysis and molecular dynamics simulation in this project. The influence of the thermal conductivity of monolayer h-BN sheet is studied and the relationship between the mechanical behavior and the thermal conductivity is presented. The theoretical prediction of thermal conductivity can be realized. The influence mechanism of stress/strain on thermal conductivity of h-BN sheet is studied by the methods similar to that of the mechanical behavior of nanomaterials. The effect of stress/strain on the thermal conductivity of h-BN sheet is declared and the technical support of stress/strain regulating thermal conductivity is provided. The factors and influent laws of thermal conductivity of multilayer h-BN sheets are studied, and the methods for controlling the thermal conductivity by stress/strain are obtained. The key problem for the application of h-BN sheets in nanoelectronic components is solved. The research, which not only provides the theoretical support for the design, performance optimization and application of the new functional nano device, but also enriches the research methods and technical means of thermal conductivity and mechanical behavior of nanomaterials, is of great significance in theory and practice.

氮化硼片的绝缘高导热和热输运性能可控的特性使其成为优异的微纳米器件，在高热流密度散热和热电材料中有着极大的应用价值，但对其导热性能的研究，当前不同的实验和理论方法得到的结果相差很大，制约着其应用和发展。本项目拟以氮化硼片的导热性能及其受力调控机理作为研究对象，采用理论分析和分子动力模拟相结合的方法，开展单层氮化硼片热导率影响规律的研究，分析力学行为与导热性能的内在关联，对其热导率进行理论预测；借助纳米材料力学行为的研究方法和手段探索应力/应变对氮化硼片导热性能的影响机理，为通过应力/应变调控导热性能提供技术支持；研究多层氮化硼片导热性能的影响因素和规律，得到应力/应变对其导热性能调控的方法，为氮化硼片在纳米电子元件中的应用解决关键的问题。该研究不仅可为新型功能纳米器件的设计、性能优化和应用提供理论依据，而且丰富了纳米材料的导热性能及力学行为的研究方法与技术手段，具有重要的理论和实际意义。

与石墨烯具有相似结构的氮化硼片具有比石墨烯更为优异的热与化学稳定性，能应用于更为恶劣的环境中，在绝缘高导热和热输运性能可控微纳米器件中有很好的应用前景，有必要通过分析单层氮化硼片和双层氮化硼片纳米材料导热性能的影响因素和规律来弄清其热输运机理，通过对受力调控热导率的机理进行研究来实现对纳米器件导热性能的有效控制。.本项目根据晶格振动理论和连续介质力学波动理论将氮化硼片力学性能与固体声波的声子平均波速关联起来，得到力学性能与热导率的关联，将B-N键的相关参数与氮化硼片力学性能关联起来，研究氮化硼片力学性能的影响因素，通过原子配位数与键长关系理论得到键长与纳米材料尺寸和手性的关系，通过出平面位移与温度关系得到键角与温度的内在联系，揭示尺度、手性和温度对氮化硼片力学影响，进而得到其对氮化硼片热导率的影响规律，探索氮化硼片热导率的尺度效应、温度效应以及手性影响规律。.通过力学性能的分子动力学模拟，分析应力应变关系与声子运动速度的关联，研究应力/应变与导热性能的内在关系，研究单层氮化硼片在拉伸、压缩等不同荷载下的应变/应力对热导率的影响规律，实现氮化硼片热导率的受力调控。.采用非平衡分子动力学方法研究双层氮化硼片的热导率，探索范德华力对热导率的影响以及热导率的影响因素，得到双层氮化硼片导热性能的影响规律。建立缺陷氮化硼片力学性能的理论模型，分析含缺陷氮化硼片的力学性能，并将结果与分子动力学模拟结果和有限元结果对比分析，验证模型合理性，为缺陷氮化硼的热导率研究提供理论支持。.通过本项目的研究，不仅实现纳米材料的属性预测，为新型功能纳米器件的设计、优化和应用提供理论依据，而且丰富纳米材料的导热性能及力学行为的研究方法与技术手段。