Preparation of SiO2/Ni core-shell type nanoparticles and their magnetic properties / 中国组织工程研究

ABSTRACT

BACKGROUND: Inhibitory coating can prevent nanoparticle oxidation, grain growth, corrosion and agglomeration, and endow nanoparticle with special properties. ABJECTIVE: 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 manometer 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 nanopartieles was successful; silica coating improved the oxidation resistance of nanometer nickel powder, endowed nanometer nickel powder better ferromagnetism and improved the coercivity.