One-dimensional (1D) nanoscale materials (nanotubles, nanorods, nanowires and nanobelts or nanoribbons and so on) are currently of a matter of much interest. Due to their unique properties in electronics, magnetics, optics, and mechanics, they can be used to design and fabricate nanosensors, switches, nanolasers, transistors and other nanodevices[1]. In order to obtain desired one-dimensional materials, many techniques and methods have been developed[2].……
The lowest-energy structures and the electronic properties of CdnSn （n = 1 - 8） clusters have been studied by using denslty-functional theory simulating package DMol^3 in the generalized gradient approximation （GGA）. The ring-like structures are the lowest-energy configurations for n = 2, 3 and the three-dimensional spheroid configurations for n = 4 - 8. The three-dimensional structures may be considered as being built from the Cd2S2 and Cd3S3 rings. Compared to the previous reports, we have found the more stable structures for CdnSn（n = 7, 8）. Calculations show that the magic numbers of CdnSn （n = 1-8） clusters are n = 3 and 6. As cluster size increases, the properties of CdnSn clusters tend to bulk-like ones in binding energy per CdS unit and Mulliken atomic charge, obtained by comparing with the calculated results of the wurtzite and zinc blende CdS for the same simulating parameters.
Composite C60-LB films were fabricated by the Langmuir-Blodgett (LB) technique, their micro- structures, micro- and macro-tribological properties were investigated using atomic force microscope/ friction force microscope (AFM/FFM). The results showed that in the confined C60-LB films there were two kinds of structures for the special C60 assembly: grain diameters of one kind were in the range of 150 -230 nm; the other was smaller than 20 nm. Mi- cro-tribological studies showed that topographical images of tiny C60 aggregates (<20 nm) were con- sistent with their frictional ones very well, namely, low friction occurred on tiny C60 aggregates compared with fatty chains LB monolayer, and ‘Micro-rolling effect’ was apparent; but for big large ones frictional forces were relatively high and ‘ratchet mechanism’ was seen apparently. Macro-tribological data proved large C60 aggregates had wear resistance and load-carrying capacities and anti-wear lives for com- posite C60-LB films were prolonged greatly with dis- persibility of C60 improved and its grain diameter re- duced. Tiny C60 aggregates were mainly the lubri- cating agents. Friction coefficients of composite C60-LB films gradually reduced with loads increasing having the same friction coefficient-load relations with boundary lubrication films.
YANG Guanghong ZHANG Xingtang XUN Jun JIANG Xiaohong ZHANG Pingyu DU Zuliang
