Study On Solution-phase Synthesis And Property Of Spherical Silver Powders

With the rapid development of electronic information technology,the demand for conductive paste is increasing,and silver powder as the main component of conductive silver paste has becomed one of the current research hotspots.By using silver nitrate solution and silver ammonia solution as precursors,and ascorbic acid as the reducing agent,spherical silver powders with different morphology and particle size were prepared.The X-ray diffractometer,scanning electron microscope,transmission electron microscope and laser particle size analyzer were used to characterize the silver powders prepared under various reaction conditions.The growth mechanism of silver powder under different conditions was explored,and an effective means for optimizing the performance of silver powder was found through comparing the effect of different experimental factors on the morphology,particle size and dispersity of silver powders.The main experimental results were as follows:(1)Spherical silver powders were prepared through liquid-phase chemical reduction method.Silver nitrate solution,ascorbic acid,polyvinylpyrrolidone(PVP)involved in this experiment were used as a precursor,a reducing agent,a surfactant respectively,and dilute ammonia,dilute nitric acid as pH regulator.Under the given process conditions(the concentration of silver nitrate solution was 0.2 mol/L,the mass ratio of ascorbic acid and silver nitrate was 0.78,the amount of PVP was 2% of the mass of silver nitrate,and reverse fast dumping method was used),spherical silver powders with smooth surface and uniform dispersibility could be prepared.whose partical size is about 1 ?m.The results showed that under the experimental conditions,the addition mode,temperature,ascorbic acid concentration,and PVP amount had great influence on the morphology and particle size of the silver powders.With the increase of the silver nitrate solution concentration,the silver particle size gradually increased.When the amount of dilute ammonia or dilute nitric acid was too much,the dispersion of silver powder will be greatly deteriorated.(2)Using silver ammonia solution as the precursor and ascorbic acid as the reducing agent,spherical silver powders were prepared by the liquid-phase chemical reduction method.The results indicated that when PVP was used as a surfactant,the prepared silver powders had better property.Based on this,the effects of nano silver seed crystals,PVP dosage,temperature,ammonia dosage,and ascorbic acid concentration on the morphology,particle size,and dispersity of silver powders were discussed,with the exception that nano silver seed crystals could reduced the partical size of silver powder,other conditions have little impact on silver powders and are suitable for industrial production.