2001 Fiscal Year Final Research Report Summary
Preparation of iron oxide/spinel ferrite and iron/spinel ferrite nanocomposite and their magnetic properties
| Project/Area Number |
12650831
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
無機工業化学
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| Research Institution | Konan University |
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Principal Investigator |
SHIGEMATSU Toshihiko Konan University, Faculty of Science and Engineering, Professor, 理工学部, 教授 (80109058)
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| Co-Investigator(Kenkyū-buntansha) |
MACHIDA Nobuya Konan University, Faculty of Science and Engineering, Assistant Professor, 理工学部, 助教授 (10190381)
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| Project Period (FY) |
2000 – 2001
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| Keywords | nanocomposite / spinel ferrite / phase separation / hard magnetic materials |
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| Research Abstract |
Low temperature oxidation of spinel type MFe_2O_4-Fe_3O_4 solid solutions (M=Zn, Co) prepared by wetmethod was investigated by XRD, VSM, Mossbauer effect and XPS measurements, and TEM observation. The phase separation to MFe_2O_4 and magnetite occurred after the oxidation in air at 300℃. The crystallitesize of separated MFe_2O_4 and magnetite was of the order of 10 nm. The magnetite phase was oxidized to γ-FezOa during the long periods of 300℃ oxidation in air, because the separated magnetite was of the order of 10 nm. Thus we obtained the MFe2O4/γ-Fe_2O_3 nanocomposite after the long periods of oxidation at 300℃.
The phase separation to MFe_2O_4 and γ-Fe_2O_3 also occurred at the initial stage of 600℃ oxidation in air. Onthe other hand, the transformation of γ-Fe_2O_3 to α-Fe_2O_3 was observed after long periods of oxidation at600℃. In the case of M=Co, the coercive force increased after the oxidation in air. The maximum value of coercive force, 2,200 Oe was obtained after the 600℃ oxidation for 90 min. Phase separation of CoZnFe_2O_4-FesO_4 solutions (bulk sample) during the low temperature oxidation in airwas similar to that observed in the spinel type MFe_2O_4-Fe_3O_4 solid solutions (M=Zn, Co) prepared by wetmethod. The increase of the coercive force after oxidation in air was also observed in this system, and themaximum value of 1,500 Oe was obtained in the CoZnFe_2O_4/α-Fe_2O_3 nanocomposite.
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