Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, U.K.
Stanford Nano Shared Facilities, Stanford University , Stanford, California 94305-4045, United States.
ACS Nano. 2015 Oct 27;9(10):9497-506. doi: 10.1021/acsnano.5b03476. Epub 2015 Jul 24.
The atomic structure and dynamics of silicon nanoclusters covalently bonded to graphene are studied using aberration-corrected transmission electron microscopy. We show that as the cluster size increases to 4-10 atoms, ordered crystalline cubic phases start to emerge. Anisotropic crystals are formed due to higher stability of the Si-C bond under electron beam irradiation compared to the Si-Si bond. Dynamics of the anisotropic crystalline Si nanoclusters reveal that they can rotate perpendicular to the graphene plane, with oscillations between the two geometric configurations driven by local volume constraints. These results provide important insights into the crystalline phases of clusters of inorganic dopants in graphene at the intermediate size range between isolated single atoms and larger bulk 2D forms.
使用相衬校正透射电子显微镜研究了共价键合到石墨烯上的硅纳米团簇的原子结构和动力学。我们表明，随着团簇尺寸增加到 4-10 个原子，有序的立方晶体相开始出现。由于与 Si-Si 键相比，Si-C 键在电子束辐照下更稳定，因此形成各向异性晶体。各向异性晶体 Si 纳米团簇的动力学表明，它们可以垂直于石墨烯平面旋转，在局部体积约束驱动下，在两个几何构型之间振荡。这些结果为在孤立的单个原子和更大的二维块状形式之间的中间尺寸范围内，石墨烯中无机掺杂剂团簇的晶体相提供了重要的见解。
