Study on spherical silver powders prepared by silver carbonate precursor modified by cladding-thermal decomposition

The silver carbonate precursor was prepared by chemical precipitation method using ammonium carbonate as precipitation agent and silver nitrate solution as raw material. The cladding silver carbonate precursor was modified by parallel flow precipitation, and the single dispersed spherical silver powders were obtained by the thermal decomposition of modified precursor. The crystallinity, purity, dispersibility, fallibility, and morphology of silver powders were characterized by X-ray diffraction (XRD), particle size distribution (PSD) statistics, tap density test, and scanning electron microscopy (SEM), the influences of silver nitrate solution concentration and methanol adding on the dispersibility and particle size distribution of silver carbonate precursor were discussed, and the effects of cladding ratio (by mole) of magnesium carbonate and silver carbonate on the dispersibility of silver powders were studied. In the results, the single dispersed spherical silver powders can be obtained by cladding-thermal decomposition, which has the advantages of simple equipment, less input, good dispersibility, and the concentrated particle size distribution of products; when the silver nitrate solution concentration is 0.2~0.5 mol/L, the particle size of spherical silver powders is 0.5~2.5 μm; the dispersibility of silver carbonate precursor can be adjusted by adding methanol, the methanol dosage (the volume fraction of methanol in silver nitrate solution) should be controlled as 5%~10%; when the silver nitrate solution concentration is 0.5 mol/L, the methanol dosage by volume is 5%, the optimum dispersibility of silver powders is obtained as the cladding ratio (by mole) of magnesium carbonate and silver carbonate is 2:1.