Synthesis and properties of Au-Pd bimetallic colloids

Gold-palladium bimetallic colloids were obtained by chemical liquid deposit ion (CLD). Two concentrations (low, high) of the metals were used. The meta ls were melted and then evaporated to yield alloy atoms, which were solvate d to yield a matrix at 77 K. Upon warming of the matrix, stable Liquid coll oids were formed. The solvents used were acetone, 2-butanone, THF, DMF, 2-e thoxyethanol, and 2-propanol. A study of particle size at room temperature performed by transmission electron microscopy (TEM) revealed that for the l ow concentration of metals the smallest mean particle sizes obtained were, respectively, 36.5, 37.7, 33.2, 27.5, 51.6, and 25.1 Angstrom. Particle siz e was found to be dependent on the solvent used. Zeta potentials were calcu lated for these negatively charged particles, using the Hunter convention a nd the Debye-Huckel equation. The films obtained after solvent evaporation were studied by thermogravimetry to determine their thermal stability. (C) 2000 Elsevier Science Ltd. All rights reserved.