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Pressure evolution of the potential barriers for transformations of layered BN to dense structures

机译:致密结构转换潜在屏障的压力演化

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摘要

Layered BN is a graphite analogue with exceptionally strong covalent bonding, while dense phases, particularly cubic and wurtzite BN are important hard materials for machine tools and other applications. BN is invariably formed in the layered form and must be converted to the dense phase under pressure. We report the pressure dependent structure of BN and energy barriers for the transformations as a function of initial structure based on first-principles methods including dispersion interactions, which we find to be important. The cohesive energies of the layered structures are similar to that of wurtzite BN. The energy barriers for transformation from rhombohedral layered BN to dense cubic BN and that from hexagonal layered BN to dense wurtzite BN are found to be similar at low pressure. Increasing pressure results in a rapid decrease of these energy barriers. The phase transition from ordered layered structures to the dense phase should be completed at approximately 25 GPa. We find a large energy barrier for layer glides under pressure, which provides an explanation for the difficulty in ambient temperature, high pressure formation of cubic dense BN from layered starting materials that contains stacking faults.
机译:分层BN是具有异常强的共价键合的石墨类似物,而致密相,特别是立方和纯钛矿BN是用于机床和其他应用的重要硬材料。 Bn总是形成为层状形式,并且必须在压力下转化为密集相。我们报告了基于第一原理方法的初始结构的变换压力依赖性结构,以及基于包括色散相互作用的第一原理方法,我们发现很重要。分层结构的粘性能量与湿钛矿BN的粘性能量类似。在低压下,发现从菱形层状BN转化为密集立方体BN的能量屏障并从六边形层状BN到致密紫硝基钛钛BN。增加压力导致这些能量屏障的快速降低。从有序的分层结构到致密相的相转变应在大约25gPa处完成。我们在压力下找到了一个大的能量屏障,这为压力下的层亮,为环境温度的难度,从含有堆叠故障的层状原料的立方体密集BN的高压形成提供了解释。

著录项

  • 来源
    《RSC Advances》 |2015年第106期|共6页
  • 作者单位

    Jilin Univ Coll Mat Sci &

    Engn Changchun 130012 Peoples R China;

    Jilin Univ Coll Mat Sci &

    Engn Changchun 130012 Peoples R China;

    Jilin Univ Coll Mat Sci &

    Engn Changchun 130012 Peoples R China;

    Univ Missouri Dept Phys &

    Astron Columbia MO 65211 USA;

  • 收录信息
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 化学;
  • 关键词

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