Synthesis and characterisation of dispersible Ni@NiO core shell magnetic nanoparticles by polyol method

Abstract

Ni@NiO core shell nanoparticles, with crystalline Ni core, NiO shell and also partially and fully amorphous NiO shell, dispersible in alcohols, have been synthesised by a polyol method. The shell thickness has been varied by either changing the concentration of the NiO precursor solution used for making the shell, or by heating the as-synthesised core shell particles at 400°C. These particles were characterised using X-ray diffraction, high resolution TEM and magnetisation studies. HRTEM studies clearly indicated the crystalline fcc cubic Ni core and thin shells of amorphous and partially amorphous NiO particles, leading to a feeble exchange bias in M-H hysteresis loop. A significant reduction in ferromagnetic component has been observed on increasing the shell thickness, or on heating the parent core shell configuration. Dispersability and magnetic nature of these samples promises a wide spectrum of applications like data storage and magnetic recording, etc.