GENERAL SYNTHESIS AND PROPERTIES OF SILVER NANOPARTICLES BY CHEMICAL REDUCTION METHOD

Synthesis of silver nanoparticles which involves a number of steps occuring in the liquid phase. First, reduction of silver nitrate in presence of ammonia solution NH4OH by strong reducing agent such as formaldehyde solution. The size and size distribution of the resulting silver nanoparticles prepared by chemical reduction are strongly dependent on the states of silver initial concentrations. Preliminary, the reduction of silver ions in aqueous solution generally yields colloidal silver with particle diameters of several nanometres. Initially, the reduction of various complexes with Ag+ ions leads to the formation of silver atoms , which are followed by agglomeration into oligomeric clusters. These clusters eventually lead to the formation of colloidal Ag particles. Furthermore, by this method the effect of different reaction parameters such as silver initial concentration, the temperature, reaction time, pH of medium and the addition of some surfactants was studied . Silver nanoparticles prepared from this method will be more stable at room temperature. The crystallite size was found in the range of 70.3 to 84.6 nm and the average particle size of the silver nanoparticles was less than 800 nm. Samples were characterized in detail by X-ray diffraction (XRD), the morphology and also the particle size of silver nanoparticles was determined by Scanning Electron Microscopy (SEM).