The Theoretical Calculations Of Aluminum Clusters And Metal Nanomaterials Preparation And Properties Of A Preliminary Study

There are mainly three parts in this paper. The first is the calculation of Al clusters in 2 to 7 atoms, the second is the simulation of preparation with flow-levitation method in theory, and the third is the preliminary study of the preparation and property of metal nanomaterials.In the need of adulterating target materials with metal clusters as tracing materials, we calculated the cluster behavior of Al materials in theory. The preliminary study was carried out in no more than 7 atoms, considering the much time in calculation and limitation of theory model Gaussian98 program, the B3LYP method and the 6-311+G* basis function were used in the calculation. The structure and energy level of the Al clusters include 2 atoms to to 7atoms was calculated with ab initio method. Discrete energy levels were found in the clusters, which is different from the energy level distribution of bulk materials. The clusters have planar structures with less than 5 atoms and three-dimensional geometric structures with more than 6 atoms. The number of the nearest atoms in the Al clusters increases with the increase of the clusters, and the number runs to 12, which is the number of the nearest atoms in bulk Al materials. The magic number did not appear in the Al clusters as in the alkali metals clusters' based on our calculation. This research based the calculation of multi-element-system clusters in the near future.The size of the nanoparticles prepared with the flow-levitation method can be controlled by controling the gas pressure in the action tube, the velocity of cooling gas flow and the temperature in the melt metal globule. Generally the average size of the particles decreases with the increase of the flow in the tube, and it increases with the rise of the temperature of the melt metal globule. The results of theory simulation are close to that of experiments. The size distribution of the particles is in agreement with the lognormal distribution. Single-crystallized particles were found in the copper nanoparticles we prepared.We preliminarily studied the preparation and the property of nano-bulk Al. The density of the Al bulk nanomaterials is only 75 percent of mat of normal ordinary coarse crystallized counterparts, which means there are a lot of holes or loosen structure in the nano-bulk Al. The nano-bulk Al should be kept more man 30 minutes at temperature no more than 300℃ to annealed which is much lower than that of ordinary Aluminum materials. The coefficient of resistance to temperature of the nano-bulk Al is more than 50 times that of ordinary Al materials. The resistance of the nano-bulk Al increases with the increase of the temperature and decrease with the increase of the grain size. The resistance of sample l#(44nm) andsample 2#(50nm) rises rapidly from 25k and 45k respectively, and an inflexion appears at the temperature in the resistance-temperature curves. The same inflexion appears at 75K in the resistance-temperature curves. The ration of the resistance at 300K to that at 1.9k of ordinary Al is about 2, however, the same ratio of the nano-metal Al is about 45, which is about 20 times that of ordinary Al's.