Iron nanoparticles by inert gas condensation: Structure and magnetic characterization

Lijuan Xing

Research output: ThesisThesis fully internal (DIV)

1569 Downloads (Pure)

Abstract

Magnetic nanoparticles are of great interest for researchers from a wide range of disciplines, e.g. catalysis, magnetic data storage, groundwater remediation, and biomedicine. Iron, with high saturation magnetization and abundant reserves, is among the most attractive candidates. We studied the controlled synthesis of iron nanoparticles by inert gas condensation. The nanoparticles are constituted by a single crystal iron core, as extensive analysis indicate, and a polycrystalline shell (Fe3O4 and/or γ-Fe2O3). Particle sizes strongly depend on the gas environment in the cluster source. We observed, meanwhile, different nanoparticle shapes including regular and truncated cubic particles, as well as regular and truncated rhombic dodecahedra, which were formed depending on the ratio of the growth rate along the <100> and the <110>direction. Moreover, it was found that iron nanoparticles revealed different morphologies depending on the size. Furthermore, in order to obtain a reduced particle size, protective backing plates are positioned in between the iron target and the magnetron, functioning as spacers to modify the magnetic field configuration above the target surface. The decrease of the particle size can be attributed to a reduced effective magnetic field strength combined with a weakened magnetic field confinement. Finally, magnetic force microscopy was employed to study the magnetic property and structure of individual iron nanoparticles with sizes ~50-70 nm. The reversal of the magnetic contrasts collected with opposite tip polarities confirms the ferromagnetic state of the studied nanoparticles, and the observed bright and dark contrasts agree with a single-domain structure.
Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • University of Groningen
Supervisors/Advisors
  • Palasantzas, Georgios, Supervisor
  • Kooi, Bart, Supervisor
Award date11-Jun-2018
Place of Publication[Groningen]
Publisher
Print ISBNs978-94-034-0707-4
Electronic ISBNs978-94-034-0708-1
Publication statusPublished - 2018

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