| Project/Area Number |
14390034
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
広領域
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| Research Institution | Osaka University |
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Principal Investigator |
YAMAMOTO Takao a. Osaka University, Department of Nuclear Engineering, Associate Professor, 大学院・工学研究科, 教授 (00174798)
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| Co-Investigator(Kenkyū-buntansha) |
SEINO Satoshi Osaka Univ., Inst.Sci.& Industrial Research, Researcher, 特別研究員
NAKAYAMA Tadachika Osaka Univ., Inst.Sci. & Industrial Research, Research Associate, 産業科学研究所, 助手 (10324849)
NAKAGAWA Takashi Osaka Univ., Dept.Nuclear Engineering, Research Associate, 大学院・工学研究科, 助教授 (70273589)
沼澤 建則 文部科学省, 物質材料研究機構, 主任研究員
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| Project Period (FY) |
2002 – 2003
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| Project Status |
Completed (Fiscal Year 2003)
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| Budget Amount *help |
¥13,400,000 (Direct Cost: ¥13,400,000)
Fiscal Year 2003: ¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2002: ¥9,700,000 (Direct Cost: ¥9,700,000)
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| Keywords | nanocomposite / iron oxide / reversed micelle / magnetocaloric effect / magnetic refrigeration / radiation / ナノ複合粒子 / 磁性材料 / 磁気エントロピー変化 |
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| Research Abstract |
We have synthesized composite nanoparticles consisting of iron oxide and gold by an inversed micelle method, which are smaller than 10 nm in total diameter and involves a narrow size distribution designated by a geometric standard deviation of 1.3. We examined the internal structure of the composite particle with techniques of TEM, ICP-chemical analysis, magnetometry, x-ray absorption fine structure, UV-vis spectrometry, and found that the present composite particles were of a core-shell structure of iron oxide and gold, respectively. This material was of the superparamagnetism at temperatures higher than 100K even though it contained iron, Fe/Au=l in atomic ratio, presumably because the gold shell well isolated the grains of iron oxide. This characteristic is welcomed from the viewpoint of the advanced magnetic refrigerant. We examined the magnetocaloric effect of the present material by evaluating its magnetic entropy change ΔS from the magnetization data sets, and found that its val
… More
ue was several times larger than those of our previous nanocomposite materials of silver and iron oxide obtained by the inert gas condensation method. We confirmed our prediction that the narrow size distribution was beneficial for the magnetocaloric effect enhancement. However, we have to increase ΔS another one order to drive the magnetic refrigeration system at the liquid nitrogen temperature and with a magnetic field given by a permanent magnet.
We also successfully synthesized a composite nanoparticle material of gold nanograins deposited on each iron oxide nanoparticle by reducing aqueous gold ions in a solution dispersing iron oxide nanoparticles. We have already applied for a patent. The deposition of gold grains is still incomplete but hiding up surface of the iron oxide particle. We can produce the composite material of several grams a day even with the present labo-scale apparatus. This material is promising for application to the biotechnology.
We have also successfully synthesized a new material family of mononitride of rare earth elements. We have found that this material exhibits ΔS far larger than those ever reported as candidate refrigerant material for the hydrogen liquefaction. Less
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