1.Preparation of Ni powder.pdf

Materials Chemistry and Physics 97 (2006) 371–378 Preparation of fine Ni powders from nickel hydrazine complex Jung Woo Park a,?, Eun H. Chae a, Sang H. Kim a, Jong Ho Lee a, Jeong Wook Kim a, Seon Mi Yoon b, Jae-Young Choi b a Materials RD Group, Passive Component Division, Samsung Electro-Mechanics Co., Ltd., 314, Suwon 443-743, Republic of Korea b Materials Devices Research Center, Samsung Advanced Institute of Technology, P.O. Box 111, Suwon 440-600, Republic of Korea Received 6 May 2005; received in revised form 9 August 2005; accepted 12 August 2005 Abstract Fine nickel powders with narrow size distribution have been prepared from the reduction of nickel hydrazine complexes in aqueous solution. The pure nickel hydrazine complexes, [Ni(N2H4)3]Cl2 were prepared with the molar ratio of N2H4/Ni2+ = 4.5, while a mixture of complexes, such as Ni(N2H4)2Cl2, [Ni(N2H4)3]Cl2, and [Ni(NH3)6]Cl2 were formed with N2H4/Ni2+ 4.5. By the X-ray diffraction (XRD), FT-IR, and scanning electron microscopy (SEM) analyses, it was found that the reduction of Ni2+ to metallic Ni powder proceeded via the formation of nickel hydroxide which was reduced by hydrazine liberated from the ligand exchange reaction between the nickel hydrazine complex and N m t c ? K 1 fi p n g c w p T f t a c t [ 0 daOH. The standard deviation of the particle size decreased with the decreasing molar concentration of nickel hydrazine complex while the ean particle size increased. As the amount of hydrazine increased, the surface roughness of the particles was improved significantly due o the catalytic decomposition of the excess hydrazine at the surface of the nickel particle. It was found that average particle size could be ontrolled from 150 to 380 nm by adjusting the reaction molar ratio and temperature. 2005 Elsevier B.V. All rights reserved. eywords: Nickel hydrazine complex; Fine nickel powder; Chemical reduction . Introduction There have been extensive studies on the synthesis of ne nickel powders in