Magnetic Properties of Monodispersed Ni/NiO Core−Shell Nanoparticles

Abstract

We have recently developed a method to fabricate monodispersed Ni/NiO core-shell nanoparticles by pulsed laser ablation. In this report, the size-dependent magnetic properties of monodispersed Ni/NiO core-shell nanoparticles were investigated. These nanoparticles were formed in two steps. The first was to fabricate a series of monodispersed Ni nanoparticles of 5 to 20 nm in diameter using a combination of laser ablation and size classification by a low-pressure differential mobility analyzer (DMA). The second step was to oxidize the surfaces of the Ni particles in situ to form core-shell structures. A superconducting quantum interference device (SQUID) magnetometer was used to measure the magnetic properties of nanostructured films prepared by depositing the nanoparticles at room temperature. Ferromagnetism was observed in the magnetic hysteresis loop of the nanostructured films composed of core-shell nanoparticles with core diameters smaller than the superparamagnetic limit, which suggests the spin of Ni core was weakly exchange coupled with antiferromagnetic NiO shell. In contrast, smaller nanoparticles with core diameters of 3.0 nm exhibited superparamagnetism. The drastic change in the hysteresis loops between field-deposited and zero-field-deposited samples was attributable to the strong anisotropy that developed during the magnetic-field-assisted nanostructuring process.

Synthesis of Nanoparticles by Laser Ablation: A Review

“…A Ni/NiO core shell structure was successfully generated by the oxidation of Ni nanoparticles. Seto et al (2004Seto et al ( , 2005 investigated the magnetic properties of Ni/NiO nanoparticles generated by this method using a superconducting quantum interference device (SQUID) magnetometer at room temperature. Ferromagnetism was observed with a film comprising nickel particles larger Another approach for overcoming the superparamagnetic limit is to synthesize highly anisotropic magnetic alloy nanoparticles such as fct FePt and CoPt.…”

Magnetic Properties of Ni/NiO Nanowires Deposited onto CNT/Pt Nanocomposites

“…[16,17] Exchange biasing has important technological applications, such as in giant-magnetoresistance-based spin valves that are used in hard-drive read heads and other spintronics applications. [18,19] In nanometer-scale systems, the key factor in this magnetic interaction would be controlling the volume, shape, crystallinity, and structure of both the FM and AFM materials. [20][21][22][23][24][25][26][27] Ni/NiO nanowires therefore offer an attractive approach to control exchange coupling, anisotropic morphology, and spin-glasslike behaviour.…”

Preparation of NiO-graphene oxide nanosensor for adsorptive stripping voltammetric determination of dinoterbon in food samples

“…However, nanostructural metal oxide semiconductors possess a high surface area, nontoxicity, good biocompatibility, catalytic activity and chemical stability. Among the metal oxide semiconductors, nickel oxide (NiO), a p-type semiconductor with a wide band gap of 4.0 eV at 300 K, has been investigated for various applications such as solar cells, electrochemistry nanosensors [20,21]. Electrochemical nanosensors based voltammetric techniques have become extremely useful for the monitoring of pesticides [22,23].…”