Nickel-Doped Ceria Nanoparticles: The Effect of Annealing on Room Temperature Ferromagnetism

Abstract

Nickel-doped cerium dioxide nanoparticles exhibit room temperature ferromagnetism due to high oxygen mobility within the doped CeO2 lattice. CeO2 is an excellent doping matrix as it can lose oxygen whilst retaining its structure. This leads to increased oxygen mobility within the fluorite CeO2 lattice, leading to the formation of Ce 3+ and Ce 4+ species and hence doped ceria shows a high propensity for numerous catalytic processes. Magnetic ceria are important in several applications from magnetic data storage devices to magnetically recoverable catalysts. We investigate the effect doping nickel into a CeO2 lattice has on the room temperature ferromagnetism in monodisperse cerium dioxide nanoparticles synthesised by the thermal decomposition of cerium(III) and nickel(II) oleate metal organic precursors before and after annealing. The composition of nanoparticles pre-and post-anneal were analysed using: TEM (transmission electron microscopy), XPS (X-ray photoelectron spectroscopy), EDS (energy-dispersive X-ray spectroscopy) and XRD (X-ray diffraction). Optical and magnetic properties were also studied using UV/Visible spectroscopy and SQUID (superconducting interference device) magnetometry respectively.

Structural, physical and chemical properties of nanostructured nickel-substituted ceria oxides under reducing and oxidizing conditions

“…3 In nanoparticles, however, Ni has been found to be soluble up to 20 at.% in Ce 1-x Ni x O 2-y obtained by a sol-gel route and 10 at.%, was reported for nanopowders obtained by the thermal decomposition of oleate metal organic precursors (crystallite size also ∼7 nm). 14 Barrio et al report a detailed XRD study describing a fluorite type structure containing ordered Ni-O-Ni entities where the Ni 2+ cations are reduced (in hydrogen atmosphere) at 400-700 °C, while the reduction of Ce 4+ to Ce 3+ is apparent as an expansion of the lattice above 700 °C. 18 Interface interactions…”

“…Nickel-doping has also been demonstrated to induce room-temperature ferromagnetism in ceria, forming a dilute magnetic semiconductor oxide. 13,14 The magnetic properties of dopedceria appear as the perfect complement to the catalytic properties by enabling the magnetic recovery of ceria catalysts. Other applications such as e.g.…”

Hydrothermal Synthesis of Gadolinium (Gd) Doped Cerium Oxide (CeO2) Nanoparticles: Characterization and Antibacterial Activity

“…The broadening of the peak in Gd doped CeO 2 NPs clearly indicates the smaller sized particles as shown in Fig.2. The average crystallite size calculated using Debye-Scherrer's formula was found in the range between 57.4-58.3 nm 19 . The size of Gd doped CeO 2 nanoparticles decreased with increasing the concentration of Gd 20 .…”

Structural, optical and magnetic properties of N ion implanted CeO2 thin films

“…4,5 The doping of transition metals like Mn, and Cu result in enhancement of ferromagnetism (FM) in CeO 2 nanocrystals. 6,7 The FM in diluted magnetic oxides (DMO) presents a major challenge in understanding its origin in such materials based on the general perception of exchange mechanisms. Dietl et al proposed that the FM in DMO is not similar to the FM in group III-IV compounds like GaAs doped with Mn.…”