Microstructures of metal nanoparticles

2^nd International Conference and Exhibition on Materials Science & Engineering

October 07-09, 2013 Hampton Inn Tropicana, Las Vegas, NV, USA

Zean A. Tian and A. B. Yu

Accepted Abstracts: J Material Sci

Abstract :

Nanoparticles have recently attracted great interest due to their novel electronic, optical, magnetic and chemical properties. Contrast to the intensive investigation for crystalline nanoparticles, less attention has been devoted to amorphous nanoparticles, partly due to the difficulties in structure characterization for disordered systems. With a newly developed parameter-free method, the structure evolutions during rapid cooling processes and in the final frozen nanoparticles have been investigated for nano-droplets each containing 10,000 silver atoms. The molecular dynamic simulations are conducted at different cooling rates from 1.0×10 11 K/s to 1.0×10 15 K/s. Take the specific short-range order of icosahedron as the indicator, the resulting nanoparticles can be divided into three categories: 1) single crystal, in which no icosahedron exists 2) multiple-twined particle, in which few icosahedrons may be appear where 12 5-fold twin boundaries meet together, and 3) amorphous nanoparticle (ANP), in which up to 12% atoms (ico-atoms) are involved in icosahedrons. Depth structure analysis for ANPs reveals that they can be further classified into three groups: 1) liquid-like ANP, which can be obtained as the cooling rate is so high that the ico-atoms are increasing (<12%) during the whole cooling process 2) ico-saturated ANP, in which the ico-atoms maintain the maximum (~12%), and 3) local crystalized ANP, in which local ordered structures composed of fcc and hcp clusters (including 13 atoms) distribute randomly. The major crystalline clusters such as fcc and hcp, are also investigated, as well as the truncated decahedrons which comprise the stem of 5-fold twin boundaries.

Biography :

Zean A. Tian has completed his Ph.D. in 2009 from Hunan University, P. R. China and is taking his postdoctoral studies at the University of New South Wales (UNSW), Australia. He focuses on the study on structural analysis of disordered systems and molecular dynamic simulation of rapid cooling for metals. He has published more than 30 papers in reputed journals and has been awarded the Vice Chancellors Postdoctoral fellowship in 2011 at UNSW, Australia.