Process for making silver powder particles with small size crystallites

A process for making silver powder particles, said process comprising:

• (a) preparing an acidic aqueous silver salt solution comprising a water soluble silver salt dissolved in deionized water;
• (b) preparing an acidic aqueous reducing and particle modifier solution comprising:
• (i) a reducing agent selected from the group consisting of ascorbic acid, ascorbates and mixtures thereof dissolved in deionized water;
• (ii) nitric acid;
• (iii) gum arabic;
• (iv) maleic acid;
• and
• (v) deionized water;
• (c) maintaining said acidic aqueous silver salt solution and said acidic reducing and particle modifier solution at the same temperature, wherein said temperature is in the range of 10° C. to 65° C., while stirring each said solution during and after preparation;
• (d) adding said acidic aqueous silver salt solution to said acidic aqueous reducing and particle modifier solution while stirring to make a reaction mixture and maintaining the temperature of said reaction mixture at said temperature of (c), wherein said silver powder particles precipitate and are contained within the resulting final aqueous solution;
• and
• (e) increasing the temperature of said final aqueous solution to a temperature in the range of 65° C. to 80° C. while continuing stirring;
• said silver powder particles comprising crystallites between 30 and 47 nm in size as determined by X-ray diffraction and the Scherrer formula;
• and
• said silver powder particles having d50 in the range of 0.5 to 3.5 μm.