Preparation of ultrafine silver powders with controllable size and morphology

The ultrafine silver powders were prepared by liquid reduction method using Arabic gum as dispersant. The effects of different dispersants, pH values, and temperature on the morphology and particle size of silver powders were investigated. It is found that Arabic gum can better adsorb on silver particles via chemical adsorption, and it shows the best dispersive effect among all the selected dispersants. The particle size of silver powders can be finely tuned from 0.34 to 4.09 mu m by adjusting pH values, while the morphology of silver powders can be tuned by changing the temperature. The silver powders with high tap density higher than 4.0 g/cm(3) were successfully prepared in a wide temperature range of 21.8-70 degrees C. Especially, the tap density is higher than 5.0 g/cm(3) when the temperature is optimized to be 50 degrees C. The facile process and high silver concentration of this method make it a promising way to prepare high quality silver powders for electronic paste.