tailieunhanh - Báo cáo hóa học: " Structure of Unsupported Small Palladium Nanoparticles Weihong Qi Æ Baiyun Huang Æ Mingpu Wang"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Structure of Unsupported Small Palladium Nanoparticles Weihong Qi Æ Baiyun Huang Æ Mingpu Wang | Nanoscale Res Lett 2009 4 269-273 DOI s11671-008-9236-z NANO EXPRESS Structure of Unsupported Small Palladium Nanoparticles Weihong Qi Baiyun Huang Mingpu Wang Received 9 October 2008 Accepted 17 December 2008 Published online 7 January 2009 to the authors 2008 Abstract A tight binding molecular dynamics calculation has been conducted to study the size and coordination dependence of bond length and bond energy of Pd atomic clusters of nm in diameter. It has been found that the bond contraction associated with bond energy increases in the outermost layer about nm in a radial way yet in the core interior the bond length and the bond energy remain their corresponding bulk values. This surface bond contraction is independent of the particle size. Keywords Lattice parameters Atomic simulation Bond energy Nanoparticles Introduction It is reported that the lattice parameter LP of nanoparticles depends on particle size 1-12 and several theoretical models have also been established to find the relation between LP and the particle size 13-16 . For non-spherical particles the shape effect on LP can be approximately predicted by the shape factor 16 where the shape factor is a modified parameter to describe the shape effect. W. Qi H M. Wang School of Materials Science and Engineering Central South University Changsha 410083 People s Republic of China e-mail W. Qi M. Wang Key Laboratory of Non-Ferrous Materials Science and Engineering Ministry of Education Changsha 410083 People s Republic of China B. Huang State Key Laboratory of Powder Metallurgy Central South University Changsha 410083 People s Republic of China However the previous work in theories or experiments only gave the mean values of LP and the difference between the interior core and the exterior surface is not considered. It is known that the surface atoms of nanoparticles have large dangling bonds but low coordination number CN than the bulk which may cause the surface to