화학공학소재연구정보센터
Journal of the Chinese Institute of Chemical Engineers, Vol.39, No.6, 673-678, 2008
A simple and effective route for the synthesis of nano-silver colloidal dispersions
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 distribution of silver colloids from this synthesis process. At the molar ratio of [Urea]/[Ag(+)]=4. [NaOH]/[Ag(+)] +0.08, the weight ratio of PVP/AgNO(3)=1 g/g, using dextrose as a reducing agent and a reaction temperature of 70 degrees C, we obtain silver colloids of average size 22nm 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 x 10(-6) Omega cm after 250 degrees C heating for 30 min. (C) 2008 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved