Thermal conductivity of giant magnetocaloric materials showing a first-order magnetic transition
| Project/Area Number |
16K04932
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Applied materials
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| Research Institution | Kyushu University |
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Principal Investigator |
Wada Hirofumi 九州大学, 理学研究院, 教授 (80191831)
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| Project Period (FY) |
2016-04-01 – 2019-03-31
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| Project Status |
Completed (Fiscal Year 2018)
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| Budget Amount *help |
¥4,810,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥1,110,000)
Fiscal Year 2018: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2017: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2016: ¥2,470,000 (Direct Cost: ¥1,900,000、Indirect Cost: ¥570,000)
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| Keywords | 巨大磁気熱量効果 / 熱伝導 / 磁気冷凍 / 一次相転移 / 熱伝導度 / 磁気熱量効果 / 磁性 |
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| Outline of Final Research Achievements |
We have studied the temperature dependence of the thermal conductivity \lambda of Mn-based giant magnetocaloric materials showing the first-order magnetic transition (FOMT) near room temperature. First, we synthesized high-quality (MnFeRu)2(PSi) samples by changing the compositions and the annealing temperature.
The thermal conductivity of (MnFeRu)2(PSi) is abruptly reduced on the first cooling due to the micro-cracks generated during the FOMT. On heating, the thermal conductivity smoothly increases with increasing temperature. It was found that the \lambda- T curve is not sensitive to the thermal cycle after the first cooling. This means that fewer micro-cracks were generated at subsequent phase transitions.The \lambda - T curves have small humps near the Curie temperature. We have proposed that the coexistence of a two-phase region by alloying is responsible for the humps in the \lambda - T curve.
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| Academic Significance and Societal Importance of the Research Achievements |
本研究の意義は巨大磁気熱量効果を示すMn化合物について良質な試料を作製する最適条件を得たことと，熱伝導度の値が室温で2 W/m K程度であることを明らかにしたことである．前者は材料開発に，後者は磁気冷凍システムの開発に重要な情報を与えるものである．また，学術的な意義としては，熱伝導に対する格子，磁気，電子の寄与の温度依存性を考察することにより，一次相転移を示す磁性体のキュリー温度近傍の熱伝導異常に初めて物理的な説明を与えたことである．これは一次相転移を示す磁性体一般に適用できるので，その意義は大きい．
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Report
(4 results)
Research Products
(14 results)
