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With the fast development of Photovoltaic industry in the world wide, the demand for the silver powders, which are of mono dispersity, spherical morphology, higher tap density as well as the size of which around 1μm, and used for the preparation of the front electrode paste, is increasing rapidly. Presently, chemical reduction in aqueous phase is the main craft for the preparation of silver powders. However, the silver powders prepared by aqueous reduction at a higher super saturation are of characteristics of serious aggregation, bad mono dispersity, low crystallinity and tap density, and far beyond the requirement for the application in the solar cells.This paper presents a precipitation-transformation method for the synthesis of silver particles by reduction in aqueous slurry. The’source materials’for the formation of the silver particles were produced by dissolving from a solid precursor gradually, through which a low super saturation of the precipitation of silver particles was realized, beneficial to the preparation of spherical, mono dispersed, high crystalline silver powders. The samples were characterized by Scanning electronic microscope (SEM), X-ray diffraction (XRD), Laser particle and Zeta potential analyzer.Silver oxide was used as the precursor for the synthesis of silver particles, the effects of reducing agent, dispersant, solvent, pH value and feeding method on the preparation of silver powders were investigated, and the reaction system for the subsequent experiments was determined as follows:glucose as reducing agent, PVP as dispersant, ammonia as pH regulator, controlled double jets process as feeding method. Eventually, the effects of the reaction conditions on the morphology and size of silver particles were studied, the results indicate that regulating the conditions of neutral pH value, low temperature, as well as glucose concentrations, was beneficial for the preparation of mono dispersed superfine silver powders and the size of which was under control. Under the conditions of 1% PVP addition (weight percentage to precursor), temperature 30℃, pH 8.0, glucose concentration 0.35 mol-L"1, silver powders of high crystallinity, good dispersity and particle size around lμm could be obtained.Submicron silver powders were prepared with silver carbonate as precursor, glucose as reducing agent, PVP as dispersant, and sodium carbonate as pH regulator. the effects of the addition amounts of the PVP and other assisted additives on the morphology and size of silver particles was investigated, it was found that adding PVP in amount less than 5% had little effect on the dispersive of silver powders; well-dispersed submicron silver powders could be obtained by adding 1.2% PVP and 0.4% sodium hexametaphosphate at the same time; the size of silver powders decreased through the addition of both of 1.2% PVP and 1% sodium citrate, and their dispersity was also enhanced.
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