posted on 2008-04-15, 00:00authored byJoseph J. McDermott, Darrell Velegol
A method is described for fabricating metallic colloidal doublets of gold−gold, silver−silver, and gold−silver.
Individual gold and silver spheres of micrometer diameter were synthesized by the aggregation of nanoparticles. Then,
by controlling aggregation using ionic strength, yields of doublets above 20% were obtained by the salting-quenching
technique. The gold−gold and silver−silver homodoublets were very stable mechanically, even in sonication; the
gold−silver heterodoublets were slightly less stable than the homodoublets in sonication. Electrical connectivity
between the gold−silver heterodoublets was verified by observing the autoelectrophoresis of gold−silver doublets
in 3% hydrogen peroxide solution. The generality of the salting out and quenching technique is demonstrated here,
and the finding that the particles are electrically connected will be of great significance in a number of applications.