Abstract
In this work we develop a simple method to synthesize nanosized Ag colloids with the addition of urea which produce intermediates AgOCN and Ag 2 CO 3 before the formation of silver. These intermediates are beneficial to obtaining high conversions of narrow size distributions of silver colloids from this synthesis process. At the molar ratio of [Ureal/[Ag + ] = 4, [NaOH]/[Ag + ] = 0.8, the weight ratio of PVP/AgNO 3 = 1 g/g, using dextrose as a reducing agent and a reaction temperature of 70 °C, we obtain silver colloids of average size 22 nm with a standard deviation of 4.7 nm after separation and washing procedures. The conversion under these conditions was nearly complete at about 98%. After a thorough washing procedure, the purity of silver colloids is up to 94.4% and its dried film is electrically conductive at room temperature. The electrical resistivity reached 4.5 × 10 -6 Ω cm after 250 °C heating for 30 min. © 2008 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.