Abstract

Bimetallic colloidal dispersions were obtained by simultaneous cocondensation of nickel and tin atoms with organic solvents at 77 K using the chemical liquid deposition (CLD) method. The atoms in a 1:1 ratio were produced by resistive heating and were reacted with 2-propanol, 2-methoxyethanol, and acetone to produce colloids. The kinetic stability of the colloid dispersions was related to the solvation effect of organic molecules, e.g., low stability for acetone, higher for 2-propanol, and the highest for 2-methoxyethanol. The colloidal particles were characterized by UV-Vis measurements showing absorption bands at 204 and 270 nm. A 3-day study in which samples were taken every hour showed that the absorption bands decrease probably due to clustering. Electrophoretic measurements revealed that the particles are weakly positively charged. Transmission electron microscopy studies revealed an average particle size distribution ranging from 6 to 10 nm depending on the solvent. Most of the colloids exhibit a spherical shape with some degree of agglomeration. After solvent evaporation several active solids were obtained. The FTIR spectra show the presence of the solvent incorporated in the active solids/films, e.g., for acetone the carbonyl stretching is observed at 1723 cm−1. The thermal stability of these bimetal powders/films was studied by TGA up to 550 °C. Their maximum decomposition temperatures are 350, 415, and 429 °C for NiSn–2-methoxyethanol, –2-propanol, and –acetone, respectively.