| Precious metal nanowires are an important kind of nano material, have an uniqueelectric, magnetic, thermal properties, such as in the fields of catalysis, sensor,microelectronic devices etc, has a broad application prospect. At present, in the theory,size of the alloy nanowires have important relations with their properties; in theexperiment, the controllablity of size in preparation is one of the most important links.Another problem is the study of the thermal stability of alloy nanowires. The differentratio of alloy nanowires will affect the properties of nanowires. For instance, themelting temperature and structure of the nanowires will change with different ratio,exhibiting strong quantum effect. So the investigation on the structure, size andthermodynamic properties of the alloy nanowires, are of great help for the experimentalpreparation of alloy nanowires.On the basis of the embedded atom potential (EAM), using molecular dynamicsmethod we have studied the effect of Platinum-Silver ratio and the cooling rate on thestructure of alloy nanowires. In addition, we have also carried out the simulation of thestructure and melting behavior of the Pt0.95Ag0.05nanowires.The calculated results are as following:(1) By considering the cases of the ratio of the three kinds of Pt0.85Ag0.15, Pt0.9Ag0.1and Pt0.95Ag0.05, the simulation studies have the confirmed that the Pt0.95Ag0.05alloynanowire holds stable structure characteristics. With the ratio decrease ofPlatinum-Silver alloy nanowires, the atomic average energy showed a downward trendand the melting point was increased(i.e., the Pt0.95Ag0.05alloy nanowire meltingtemperature is about800K which is largely higher than those of Pt0.85Ag0.15and Pt0.9Ag0.1).(2) In the process of quenching, cooling rate determines the state of the finalstructure of Platinum-Silver nanowires. However, the Platinum-Silver ratio have littleimpact on it. Whether the final structures of Platinum-Silver alloy nanowires are orderly,are depend on cooling rate in the process of quenching. The fastest cooling rate is5×1011K/s for the Platinum-Silve alloy nanowires presenting a crystalline state at thedifferent ratio. When the value is greater than this rate, the eventual structure ofPlatinum-Silve alloy nanowires will become a disorderly amorphous state. This can alsobe confirmed through the potential energy and temperature curve of the different ratio of Platinum-Silve alloy nanowires. In the process of quenching, with the decrea-sing ofthe temperature the orderly degree of the Platinum-Silve nanowires structure at differentratio will increase.(3) Based on the EAM potential, we have carried out molecular dynamicssimulation on the structure and melt behavior of Pt0.95Ag0.05nanowires. Through theresearches of the thermalization process of Pt0.95Ag0.05nanowires, the results showthat:i) Pt0.95Ag0.05alloy nanowire melting point increases with the radial size; ii) themelting point of S-1and S-3structure of the Pt0.95Ag0.05nanowires is around620K,S-2around720K. Lindemann index and structural evolution process imply that themelting order of Pt0.95Ag0.05nanowires is out-to-in.The above research conclusions will help us to understand the fusion mechanismof platinum-silver nanowires in theory. Furthermore, they will also have importantguiding significance for the construction and preparation of platinum-silver nanowiresin the experiment. |
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