Stelmakh Svitlana, Skrobas Kazimierz, Gierlotka Stanislaw, Palosz Bogdan
Institute of High Pressure Physics PAS, Sokolowska 29/37, Warsaw, 01-142, Poland.
National Centre for Nuclear Research, A. Soltana 7, 05-400 Otwock/Swierk, Poland.
J Phys Condens Matter. 2021 Apr 23;33(17). doi: 10.1088/1361-648X/abe26a.
Atomic structure of plate-shaped nanodiamonds synthesized from chloroadamantane was identified with application of large-powder diffraction data. Both reciprocal and real space methods of experimental data analysis were applied. Theoretical atomistic models of nanodiamonds were obtained with application of molecular dynamics (MD) simulations. It was found that examined nanodiamond samples with average grain size from 1.2 up to 2.5 nm are plates build from only six hexagonal carbon layers and they are terminated by (111)B surfaces with three dangling bonds. MD simulations showed that as a result of relaxation of surface stresses there appears a complex system of compressive and tensile strains across and parallel to the surface of the plate-nanodiamonds. Identification of the internal structure of nanodiamond was performed based on the analysis of differential interatomic distance diagrams derived from pair distribution functions(). Based on MD simulations an atomic model of plate-grains of diamond was elaborated. Usefulness of lattice parameters determined in a routine diffraction data analysis for characterization of nanodiamonds is questioned. As an alternative the application of the apparent lattice parameter is recommended. A dependence of the overall apparent lattice parameter 〈alp〉 on the size and shape of nanodiamond grains terminated by low index crystal faces is presented.
利用大粉末衍射数据确定了由氯代金刚烷合成的板状纳米金刚石的原子结构。采用了实验数据分析的倒易空间和实空间方法。通过分子动力学（MD）模拟获得了纳米金刚石的理论原子模型。结果发现，所研究的平均粒径为1.2至2.5纳米的纳米金刚石样品是仅由六个六边形碳层构成的板，并且它们由具有三个悬空键的（111）B表面终止。MD模拟表明，由于表面应力的松弛，在板状纳米金刚石的表面上出现了一个复杂的压缩和拉伸应变系统，该系统跨越并平行于表面。基于对由对分布函数导出的差分原子间距离图的分析，对纳米金刚石的内部结构进行了鉴定。基于MD模拟，构建了金刚石板状晶粒的原子模型。对常规衍射数据分析中确定的晶格参数用于表征纳米金刚石的实用性提出了质疑。作为替代方案，建议应用表观晶格参数。给出了由低指数晶面终止的纳米金刚石晶粒的整体表观晶格参数〈alp〉对其尺寸和形状的依赖性。
