Synthesis and characterization of Zn-Cd bimetallic colloids from nonaqueous solvents

Bimetallic colloids of Zn-Cd were prepared with different organic solvents, namely, THF, 2-methoxyethanol, 2-propanol, 2-butanone, 2-butanol, and acetone. The metals were evaporated to yield atoms, which were codeposited at 77 K with solvents to produce solvated metal atoms. Upon warming the matrix at room temperature, liquid colloid dispersions were formed. Different metal concentrations were used. Colloid stability was analyzed in terms of flocculation at room temperature. The lowest stability was shown for THF dispersions (2-4 h) and the highest was obtained for acetone (6-10 days) at dilute concentrations. Particle sizes were obtained by transmission electron microscopy (TEM). The particles in the bimetallic colloids had spherical shape, and average particle sizes ranged between 69 and 148 Angstrom. The mobility of the particles was determined by electrophoresis, Particles in the Zn-Cd 2-butanone and acetone colloids had electrophoretic mobility and zeta potential values between 0.14 and 0.97 V, showing behavior typical of charged surfaces. (C) 2000 Elsevier Science Ltd. All rights reserved.