Investigating the role of shell thickness and field cooling on saturation magnetization and its temperature dependence in Fe3O4/γ-Fe2O3 core/shell nanoparticles

Ihab M. Obaidat, Chiranjib Nayek, Kaustuv Manna

Research output: Contribution to journalArticlepeer-review

24 Citations (Scopus)

Abstract

Understanding saturation magnetization and its behavior with particle size and temperature are essential for medical applications such magnetic hyperthermia.We report the effect of shell thickness and field cooling on the saturation magnetization and its behavior with temperature in Fe3O4/γ-Fe2O3 core/shell nanoparticles of fixed core diameter (8 nm) and several shell thicknesses. X-ray diffraction (XRD) analysis and transmission electron microscopy (TEM, high-resolution transmission electron microscopy (HRTEM)) were used to investigate the phase and the morphology of the samples. Selected area electron diffraction (SAED) confirmed the core/shell structure and phases. Using a SQUID (San Diego, CA, USA), magnetic measurements were conducted in the temperature range of 2 to 300 K both under zero field-cooling (ZFC) and field-cooling (FC) protocols at several field-cooling values. In the ZFC state, considerable enhancement of saturation magnetization was obtained with the increase of shell thickness. After field cooling, we observed a drastic enhancement of the saturation magnetization in one sample up to 120 emu/g (50% larger than the bulk value). In both the FC and ZFC states, considerable deviations from the original Bloch's law were observed. These results are discussed and attributed to the existence of interface spin-glass clusters which are modified by the changes in the shell thickness and the field-cooling.

Original languageEnglish
Article number1269
JournalApplied Sciences (Switzerland)
Volume7
Issue number12
DOIs
Publication statusPublished - Dec 5 2017

Keywords

  • Bloch's law
  • Magnetization
  • Nanoparticles
  • Shell thickness

ASJC Scopus subject areas

  • General Materials Science
  • Instrumentation
  • General Engineering
  • Process Chemistry and Technology
  • Computer Science Applications
  • Fluid Flow and Transfer Processes

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