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

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

doi:10.1016/j.jeurceramsoc.2011.08.028

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

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

Research output: Contribution to journal › Article › peer-review

13 Citations (Scopus)

Abstract

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 language	English
Pages (from-to)	419-424
Number of pages	6
Journal	Journal of the European Ceramic Society
Volume	32
Issue number	2
DOIs	https://doi.org/10.1016/j.jeurceramsoc.2011.08.028
Publication status	Published - 2012 Feb

Keywords

Hot spot
Magnetite
Microstructure
Microwave
Selective heating

ASJC Scopus subject areas

Ceramics and Composites
Materials Chemistry

Access to Document

10.1016/j.jeurceramsoc.2011.08.028

Cite this

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

abstract = "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.",

keywords = "Hot spot, Magnetite, Microstructure, Microwave, Selective heating",

author = "Noboru Yoshikawa and Guoqiang Xie and Ziping Cao and Louzguine, {Dmitri V.}",

note = "Funding Information: The authors are grateful for the financial support by Grant-in-Aid of Ministry of Education, Sports, Culture, Science and Technology, Japan , Priority Area on Science and Technology of Microwave-Induced, thermally Non-Equilibrium Reaction Field , and by Grant-in-Aid, Exporatory Research by JSPS .",

year = "2012",

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language = "English",

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AU - Yoshikawa, Noboru

AU - Xie, Guoqiang

AU - Cao, Ziping

AU - Louzguine, Dmitri V.

N1 - Funding Information: The authors are grateful for the financial support by Grant-in-Aid of Ministry of Education, Sports, Culture, Science and Technology, Japan , Priority Area on Science and Technology of Microwave-Induced, thermally Non-Equilibrium Reaction Field , and by Grant-in-Aid, Exporatory Research by JSPS .

PY - 2012/2

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N2 - 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.

AB - 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.

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KW - Magnetite

KW - Microstructure

KW - Microwave

KW - Selective heating

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