ALLOYING BEHAVIOR OF GOLD ATOMS INTO NM-SIZED COPPER CLUSTERS

Alloying behavior of gold atoms into copper clusters has been studied using a 200 kV transmission electron microscope (TEM) equipped with a double source evaporator in the specimen chamber. Isolated copper clusters of approximately 4 nm in diameter were first prepared on a supporting film of amorphous carbon, and then gold atoms were deposited onto the same film kept at room temperature. Upon the deposition of gold, the copper clusters quickly changed into homogeneously mixed Cu-Au alloy clusters. The gold diffusivities in the clusters estimated from the experimental results are at least 19 orders of magnitude faster than those in the bulk copper.