RESUMEN
In this paper, we provide a theoretical basis using thermodynamic stability analysis for explaining the spontaneous nucleation and growth of a high density of 1-D structures of a variety of materials from low-melting metals such as Ga, In, or Sn. The thermodynamic stability analysis provides a theoretical estimate of the extent of supersaturation of solute species in molten metal solvent. Using the extent of maximum supersaturation, the size and density of critical nucleus were estimated and compared with experimental results using nucleation and growth of Ge nanowires using Ga droplets. The consistency of the proposed model is validated with the size and density of the resulting nanowires as a function of the synthesis temperature and droplet size. Both the experimental evidence and the theoretical model predictions point that the diameters of the resulting nanowires decrease with the lowering of synthesis temperatures and that the nucleation density decreases with the size of metal droplet diameter and increasing synthesis temperature.
RESUMEN
A concept is presented for synthesizing metal nanowires directly from the vapor phase using chemical vapor transport to temperatures higher than the corresponding metal oxide decomposition temperature. Specifically, this concept is demonstrated with the synthesis of tungsten metal nanowires with sizes ranging from 70 to 40 nm by increasing the condensation temperature. The simultaneous condensation and decomposition of the tungsten oxide species during nucleation and growth is suggested for 1-D growth of metallic tungsten nanowires. This synthesis concept could potentially be extended to the vapor phase synthesis of metal nanowires of several other nonvolatile and refractory metals. The tungsten nanowires could find potential applications in gas sensors and as electron sources in electron microscopes.