Abstract

Monodispersed flaky silver powder was obtained by controlling the ratios of H_2O_2/NH_3 and Agin in a mixed solution of ethylene glycol and ammonia with an addition of PVP. The effects of NH_3/Ag,; H_2O_2/Ag;and;H_2PtCl_6/Ag on its morphology and size were investigated. In H_2O_2-NH_3-AgNO_3;system,;NH_3/Ag molar ratio was found to be an important reaction factor for the nucleation and crystal growth of Ag powder. The synthesis of flaky powder was optimized at over 6 of NH_3/Ag ;and;5;of;H_2O_2/Ag;under;1.0times10-3;of;Pt/Ag.;Moreover,;as;the; NH_3/Ag molar ratio increased, the size of precipitates was increased regardless of the amount of Pt. In the absence of H_2PtCI, the morphology and size of reduced Ag powder were found to be irregular in shape 2-4µm in diameter. However, homogenized fine Ag powder was obtained due to heterogeneous nucleation when H_2PtCI used as a cat-alyst, and flaky one was synthesized with the addition of Pt over 1.0times10-3 of Pt/Ag.

• Keywords: Morphology control;flaky Ag powder;chemical reduction;ethylene glycol; heterogeneous nucleation;