Colloidal metals atomic metal evaporation

The experimental apparatus used consisted of a stationary metal atom-vapor reactor which has been detailed in the literature earlier. (39) Metal was evaporated (-0.1 to 0.5 g) and codeposited at -196°C with excess organic solvent vapor (- MO-150 mL). The frozen matrix was allowed to warm under controlled conditions, and upon melting stirring was commenced. After warming to room temperature stable colloidal solutions were obtained and syphoned out under N. ... 

Copper, silver, and gold colloids have been prepared by Chemical Liquid Deposition (CLD) with dimethoxymethane, 2-methoxyethyl ether, and ethylene glycol dimethyl ether. The metals are evaporated to yield atoms which are solvated at low temperatures and during the warm-up process colloidal sols with metal clusters are obtained. Evaporation of the solvent was carried out under vacuum-generating metal films. These films are showing very low carbon/hydrogen content and were characterized by elemental analyses and infrared spectroscopy (Cardenas et al., 1994). 

There are also other methods such as spray pyrolysis and electrospray pyrolysis besides the above method [26]. To prepare nanoparticles by spray pyrolysis, a starting solution is prepared by dissolving, usually, the metal salt of the product in the solvent. The droplets atomized from a starting solution are introduced to furnace. Drying, evaporation of solvent, diffusion of solute, precipitation, reaction of precursor, and surrounding gas, pyrolysis may occur inside the furnace before the formation of product. It is similar to spray drying except the type of precursor. For this, colloidal particles are typically used as precursors. Some products prepared by spray pyrolysis are listed in Table 34.1. 

---