Structure, morphology and magnetic properties of flowerlike gamma-Fe2O3@NiO core/shell nanocomposites synthesized from different precursor concentrations

Xuemin He, Chuangwei Zhang, Fangfang Guo, Qinghai Zhou, Yongtao Li*, Hongguang Zhang, Liqing Liu, Youwei Du, Wei Zhong

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

The flowerlike gamma-Fe2O3@NiO core/shell nanocomposites are synthesized by the two-step method. Their structure and morphology can be controlled by tuning the precursor concentration. Microstructural analysis reveals that all the samples have distinct core/shell structure without impurities, and the NiO shells are built of many irregular nanosheets which enclose the surface of gamma-Fe2O3 core. As the precursor concentration decreases (i.e., more NiO content), the NiO grain grows significantly, and the thickness of NiO shells increases. Magnetic experiments are performed to analyze the influences of different microstructures on magnetic properties of samples and we have the following two results. First, at 5 K, along with increasing thickness of NiO shell, the saturation magnetization increases, while the residual magnetization decreases slightly. Second, the hysteresis loops under cooling field demonstrate that the value of exchange bias effect fluctuates between 13 Oe and 17 Oe. This is mainly because of the NiO shell that (i) is composed of irregular nanosheets with disordered orientations, and (ii) does not form a complete coating around gamma-Fe2O3 core.

Original languageEnglish
Article number110495
Number of pages7
JournalMaterials Research Bulletin
Volume118
DOIs
Publication statusPublished - Oct-2019

Keywords

  • Precursor concentration
  • Microstructure
  • Interface
  • Freezing temperature
  • Exchange bias
  • EXCHANGE BIAS
  • SIZE
  • NANOPARTICLES
  • COERCIVITY
  • SPECTRA
  • SHELL

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