Microstructure of selectively heated (hot spot) region in Fe3O4 powder compacts by microwave irradiation

Noboru Yoshikawa, Guoqiang Xie, Ziping Cao, Dmitri V. Louzguine

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13 Citations (Scopus)


An Fe3O4 powder compact was irradiated with a 2.45GHz microwave single-mode applicator at the magnetic field maximum position. Selectively heated regions (hot spot region) having several hundred micrometers to millimeter scale were formed. They exhibited metallic color. The SEM/EDX observations showed no appreciable difference in the compositions between the hot spot regions and the matrix. However, micro-XRD revealed that the hot spot region had a larger fraction of FeO than the matrix did, although the major consisting phase was Fe3O4 with a little Fe2O3. TEM observations indicated that the observed hot spot regions comprise these oxide phases separated in nano-sized grains, which agrees with our previous report. The larger fraction of FeO phase and flat surface might be related with the metallic color of the hot spot region. Their formation mechanisms and phase constitution were discussed.

Original languageEnglish
Pages (from-to)419-424
Number of pages6
JournalJournal of the European Ceramic Society
Issue number2
Publication statusPublished - 2012 Feb


  • Hot spot
  • Magnetite
  • Microstructure
  • Microwave
  • Selective heating

ASJC Scopus subject areas

  • Ceramics and Composites
  • Materials Chemistry


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