CONTROLLED NUCLEATION AND GROWTH OF MICROMETER-SIZE COPPER PARTICLES PREPARED BY THE POLYOL PROCESS

Fine, equiaxed copper particles have been obtained by reduction of CuO in ethylene glycol. Cu2O always exists as an intermediate solid phase . Copper particles with a narrow size distribution within the micromet re range can be obtained if the nucleation and growth steps are comple tely separated and if agglomeration is avoided. Addition Of D-Sorbitol , which acts as a protective agent, prevents particle sintering. Addit ion of a strong base, e.g. NaOH, enhances the solubility of the precur sor CuO and of the intermediate Cu2O. Under these conditions the overa ll reaction appears to be controlled by the nucleation and growth step s of the metallic particles. Their mean size can be largely controlled by varying the NaOH concentration. The synthesis of copper particles in liquid polyols, which act as both solvent and reducing agent, is a simple method for producing highly pure, equiaxed, non-agglomerated mo nodisperse particles.