Preparation of SiO2/Ni core-shell type nanoparticles and their magnetic properties☆◆

Dong Xing-long, Liu Jin-xuan, Huang Hao, Wang Wei-na, Zhang Xue-feng, Lei Jun-peng,
Zhu Xu-guang

State Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, School of Materials Science and Engineering of Dalian University of Technology, Dalian 116023, Liaoning Province, China

Dong Xing-long☆, Doctor, Professor, State Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, School of Materials Science and Engineering of Dalian University of Technology, Dalian 116023, Liaoning Province, China
dongxl@dlut.edu.cn

Correspondence to: Huang Hao, State Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, School of Materials Science and Engineering of Dalian University of Technology, Dalian 116023, Liaoning Province, China
huanghao@dlut.edu.cn

Received: 2008-03-27
Accepted: 2008-05-05
(54200803260009/N)

Dong XL, Liu JX, Huang H, Wang WN, Zhang XF, Lei JP, Zhu XG.Preparation of SiO2/Ni core-shell type nanoparticles and their magnetic properties.Zhongguo Zuzhi Gongcheng Yanjiu yu Linchuang Kangfu 2008;12(27): 5397-5400(China)
[www.zglckf.com/zglckf/ejournal/upfiles/ 08-27/27k-5397 (ps).pdf]

Abstract
BACKGROUND: Inhibitory coating can prevent nanoparticle oxidation, grain growth, corrosion and agglomeration, and endow nanoparticle with special properties.
OBJECTIVE: To prepare SiO2/Ni core-shell type nanoparticles and assess their magnetic properties.
DESIGN, TIME AND SETTING: The observation experiment was performed between November 2005 and March 2006 at Nanometer Compound Material Research Laboratory of Dalian University of Technology, Dalian, Liaoning Province, China.
MATERIALS: Nanometer nickel powder prepared by DC arc plasma jet method, Na2SiO3 produced by Bazhou Chemical Industry Branch Factory of Tianjin Quartz Clock Factory (China).
METHODS: SiO2/Ni core-shell type nanoparticles were synthesized by coating a layer of SiO2 on the surface of nanometer nickel powder via liquid deposition method using Na2SiO3 as the main source material.
MAIN OUTCOME MEASURES: Their microstructures and material properties were investigated by X-ray diffraction, Fourier transform infrared spectrometer, transmission electron microscopy, thermo-gravimetric analysis, differential scanning calorimetry and vibrating sample magnetometer.
RESULTS: The experimental results showed that SiO2 shell was in an amorphous state around Ni cores and it avoided agglomeration of the Ni nanoparticles. The oxidation temperature of nanometer nickel powder coated by SiO2 elevated from 287 ℃ to 385 ℃. The analysis result of magnetic properties indicated that the hysteresis loop of Ni had an excursion for the existence of anti-ferromagnetic NiO, the silica coating reduced the saturation magnetization and improved the coercivity.
CONCLUSION: Preparation of SiO2/Ni core-shell type nanoparticles was successful; silica coating improved the oxidation resistance of nanometer nickel powder, endowed nanometer nickel powder better ferromagnetism and improved the coercivity.