Coordination-dependent surface atomic contraction in nanocrystals revealed by coherent diffraction

被引:309
作者
Huang, W. J. [1 ,2 ]
Sun, R. [1 ,2 ]
Tao, J. [1 ,2 ]
Menard, L. D. [2 ,3 ]
Nuzzo, R. G. [2 ,3 ]
Zuo, J. M. [1 ,2 ]
机构
[1] Univ Illinois, Dept Mat Sci & Engn, Urbana, IL 61801 USA
[2] Univ Illinois, Frederick Seitz Mat Res Lab, Urbana, IL 61801 USA
[3] Univ Illinois, Dept Chem, Urbana, IL 61801 USA
基金
美国国家科学基金会;
关键词
D O I
10.1038/nmat2132
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
Surface atoms have fewer interatomic bonds than those in the bulk that they often relax and reconstruct on extended two-dimensional surfaces. Far less is known about the surface structures of nanocrystals. Here, we show that coherent diffraction patterns recorded from individual nanocrystals are very sensitive to the atomic structure of nanocrystal surfaces. Nanocrystals of Au of 3-5nm in diameter were studied by examining diffraction intensity oscillations around the Bragg peaks. Both results obtained from modelling the experimental data and molecular dynamics simulations strongly suggest inhomogeneous relaxations, involving large out-of-plane bond length contractions for the edge atoms (similar to 0.2 angstrom); a significant contraction (similar to 0.13 angstrom) for {100} surface atoms; and a much smaller contraction (similar to 0.05 angstrom) for atoms in the middle of the {111} facets. These results denote a coordination/facet dependence that markedly differentiates the structural dynamics of nanocrystals from bulk crystalline surfaces.
引用
收藏
页码:308 / 313
页数:6
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