Au–Cu bimetallic colloids prepared by cocondensation with nonaqueous solvents

Au–Cu colloids were prepared by chemical liquid deposition (CLD). The metals were evaporated simultaneously to yield atoms, which were solvated to yield bimetal atom mixtures at 77 K, and upon warming, in some cases, stable liquid colloids were formed with a narrow range of particle size. The solvents under study were acetone, 2-butanone, 2-propanol, 2-methoxyethanol, 2-ethoxyethanol, diglyme, THF, and DMF. The particle size of the bimetallic colloids ranged from 21 to 48 Å. The films or powders were prepared by direct evaporation of the solvents from bimetallic colloids. Microanalysis demonstrated that these films contained carbon and hydrogen residues. Infrared spectra showed that hydrocarbon residues were present in the films. Thermal studies demonstrated the low stability of the Au–Cu films. Two or three decomposition temperatures were observed in the thermograms. In most of the films, a total weight loss of 10–15%, at 550°C, was registered.