Growth Mechanism of Penta-twinned Ag Nanowires Synthesized by Polyol Process

Abstract

Multi-twinned silver nanoparticles and nanowires were synthesized by polyol process in the presence of surfactant poly (vinyl pyrrolidone) (PVP) K30. In order to study the growth mechanism, silver nanowires were synthesized under various conditions by changing n(PVP)/n(AgNO3) and the state of agitation. A comparative study of these nanowires was performed by means of transmission electron microscopy (TEM) and optical absorption spectra. The results showed that there coexisted two different growth modes, and hence the competition between them. According to one mode, the as-synthesized nanowires grew along {111} faces, by which the pentagonal pyramid-shaped tip was enclosed, as the active facets. By another mode, the nanowires grew layer by layer along{110} face, which was perpendicular to the wire axis [110], as the active facet. There were many stacking faults and dislocations in the nanowires deformed plastically during the preparation of the nanowires. The fresh fracture surfaces of the nanowires were the favorable positions where the nucleation and growth of newly formed crystals might take place.