几种典型硼—碳—氮超硬材料的结构设计

发布时间：2018-01-25 01:41

本文关键词： 第一性原理超硬材料晶体结构设计　出处：《吉林大学》2016年博士论文　论文类型：学位论文

【摘要】：超硬材料广泛应用于国防和工业生产中,新型超硬材料的设计与合成一直备受大家的关注。本文利用高效的CALYPSO晶体结构理论预测方法,结合第一性原理计算,选取最有潜力成为超硬材料的硼、碳、氮的化合物为研究对象,开展了系统性的新型超硬材料的设计研究,获得了如下创新性结果：1.尽管实验上成功合成立方BC2N、c-BC5和c-BC3等新型超硬材料,但实验和理论仍无法确定这些材料的晶体结构。本论文通过CALYPSO方法首次确定了实验上合成的具有立方金刚石结构的BC3相(d-BC3),揭示了其近各向同性和良好的延展性是由于特殊的成键方式和成键相继破坏机制决定。本研究工作解决了困扰多年的立方BC3相的结构难题,为日后进一步解决其它B-C化合物的晶体结构奠定了理论基础。2.设计了一种新型正交相超硬碳,命名为oC32碳,可以通过石墨加压来合成,该超硬相具有明显的能量优势,低于前人理论提出的系列冷压石墨碳的能量,为实验合成该超硬相提供了理论基础。3.设计了四种具有高效的光电转换率的二维B-N-C光学功能材料,带隙宽度在可见光的能量区间内,确定了混合不同浓度的石墨烯和h-BN可实现对Bx/2Nx/2C1-x带隙宽度的调控,为探索新一代的太阳能光电材料奠定了一定的理论基础。
[Abstract]:Superhard materials are widely used in national defense and industrial production, and the design and synthesis of new superhard materials have been attracting much attention. In this paper, the efficient prediction method of CALYPSO crystal structure is used. Based on the first principle calculation, the systematic design of new superhard materials was carried out by selecting the compounds of boron, carbon and nitrogen, which have the most potential to become superhard materials. The following innovative results have been obtained: 1. In spite of the successful synthesis of new superhard materials such as cubic BC2NC5 and c-BC3 in experiments. However, the crystal structure of these materials can not be determined by experiments and theories. In this thesis, the synthesized BC3 phase with cubic diamond structure has been determined by CALYPSO method for the first time. It is revealed that its near isotropy and good ductility are determined by the special bonding mode and bond successive destruction mechanism. This work solves the structural problem of cubic BC3 phase which has been puzzling for many years. It lays a theoretical foundation for further solving the crystal structure of other B-C compounds in the future. 2. A new type of orthotropic superhard carbon named oC32 carbon can be synthesized by graphite pressurization. The superhard phase has obvious energy advantage, which is lower than that of series of cold pressed graphite carbon proposed by previous theories. It provides a theoretical basis for the experimental synthesis of the superhard phase. 3. Four kinds of two-dimensional B-N-C optical functional materials with high photoelectric conversion rate are designed. The band gap width is in the energy range of visible light. It is determined that the band gap width of Bx/2Nx/2C1-x can be controlled by mixing graphene and h-BN with different concentrations, which lays a theoretical foundation for the exploration of a new generation of solar photovoltaic materials.
【学位授予单位】：吉林大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TQ163

【相似文献】