García-Marcano, Glorimar

Profile Picture

Filters

Reset filters

Settings

Citations

Publication Search Results

Now showing 1 - 1 of 1
  • Thumbnail Image
    Publication
    Size - and shape - controlled synthesis of silver nanostructures for potential high thermal conductivity applications
    (2012) García-Marcano, Glorimar; Perales-Pérez, Oscar J.; College of Engineering; Gustavo Gutierrez, Jorge; Valentín, Ricky; Department of Mechanical Engineering; Santana, Alberto
    Nanofluids, which are based on the use of nanoscale particles suspended in a base fluid, have become a new alternative for improving heat management technology. Ultra fine and monodisperse solid silver particles are a very promising material for cooling fluids as they are known to exhibit the highest electrical and thermal conductivity of among metals. This project is focused on the effect of silver crystal size and shape on the thermal conductivity of the suspensions prepared at various concentrations in ethylene glycol, a typical cooling fluid. The crystal size and shape at the nanoscale are controlled by the synthesis conditions and the presence of shape-control agents like chloride salts. The specific shape-control on the silver nanostructures was achieved by the proper selection of the mole ratios of PVP/Ag in the starting solutions and the type and level of chloride salts such as NaCl and FeCl2, which were significant for the final formation of the silver nanostructures (faceted crystals, wires, rods). These nano structures were remarkably monodisperse in size; the particle diameter could be controlled in the 30 – 50 nm range and the rod or wire thickness in the 24 – 127 nm range. In the case of KCl and CaCl2, the formation of silver nanowires (SNWs) exhibited a very uniform thickness that could be tuned within the range of 40 – 130 nm at 30 minutes of the reaction mixture. UV-Vis measurements evidenced the plasmon peak at ~387 nm and clear shoulders at ~357 nm that are indicative of the formation of elongated nanostructures. Synthesized nanostructures were characterized by X-ray diffraction (XRD and UV-Vis spectroscopy, scanning electron microscope (SEM) and transmission electron microscope (TEM). The influence of size and shape properties, stable dispersion between nanorods and nanowires showed a slight enhancement of thermal conductivity when silver nanostructures (10-15% v/v) were suspended in the base fluid.