Resumen de Synthesis and tem studies of gallium colloids prepared in nonaqueous solvents
Galo Cardenas, Silvana Salinas, Ricardo Oliva C
In this work metallic colloidal dispersions were obtained by simultaneous co-condensation of gallium atoms with organic solvents at 77 K. The atoms were produced by resistive heating and were reacted with ethanol, 2-propanol, 2-methoxyethanol, acetone and 2-butanone to produce colloids. The kinetic stability of colloid dispersions was related to the solvation effect of organic molecules, e.g. low stability for ketones and higher stability for 2-propanol colloids. The electrophoretic measurements reveal that particles are negatively charged being 5.1 V for 2-propanol and 0.5 V for 2-butanone. The colloids of Ga-2-propanol and Ga-2-methoxyethanol exhibit an absorption band at 213 and 209 nm, respectively. The transmission electron microscopy studies reveals an average particle size distribution ranging from 1.0 to 1.2 mm depending on the solvent. Most of the colloids exhibit a spherical shape with some degree of agglomeration. The electron diffraction of Ga-colloids shows the presence of a mixture of Ga and Ga2O3 particles. After solvent evaporation, amorphous active powders were obtained. The solids were analyzed by thermogravimetry being Ga-2-methoxyethanol the most stable with a decomposition temperature of 308° C. The Ga-acetone shows two decomposition decays at 98 and 223° C, respectively. Similar behavior was obtained with 2-butanone. The FT-IR confirms the presence of the solvent in the powders. In the case of Ga-acetone and Ga-2-butanone a nu C=O at 1728 cm-1 reveals the solvent incorporation in the active solids.
