Synthesis and physical properties of nickel nanoparticlesand Ni/SiO2 Core/Shell structure

Abstract

Magnetic nanoparticles with critical size below 10-20 nm currently attract attention as theyhave distinctive properties such as a large magnetic moment and behave like giantparamagnetic atoms with a fast response to applied magnetic fields with negligibleremanence and coercivity. In addition, they have a single magnetic domain and showsuperparamagnetic behaviour with blocking temperature. These characteristics makesuperparamagnetic nanoparticles possess significant applications in biomedical fields.However, nanoparticles need to be protected to be stable and avoid the loss of theirmagnetism. This can be accomplished by coating nanoparticles with organic species or withan inorganic layer, such as silica. The protecting shells not only stabilise the nanoparticles,but can also be used for further functions. This work presents experimental results on thepreparation of fine Ni/NiO nanoparticles via a reduction method. The nanoparticles wereprepared by reducing nickel-acetate with 1-propanol in the presence of Pd seeds andpolyvinylpyrrolidone (PVP) as a stabiliser. The nanoparticles were further coated with silica(SiO2) by hydrolysis of tetraethyl orthosilicate (TEOS) in 2-propanol, both with and without aprimer (gelatine). The effect of reaction conditions on coating was studied. The nature andcharacteristics of the Ni nanoparticles and Ni/SiO2 were studied by a number of techniquessuch as Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Transmissionelectron microscopy (TEM), energy-dispersive x-ray spectroscopy (EDX) and FourierTransform-Infrared Spectroscopy (FTIR). The magnetic measurements of Ni nanoparticleswas performed by using superconducting quantum interference device (SQUID)magnetometer.Finally, an overview of the project is presented and techniques that have been used tocharacterise nanoparticles. The experimental is outlined in chapter 4.

Date of Award	31 Dec 2011
Original language	English
Awarding Institution	The University of Manchester
Supervisor	John Prabhakar (Supervisor)