2007 Fiscal Year Final Research Report Summary
Experimental studies of novel magnetic refrigerants by high field X-ray diffraction measurements
| Project/Area Number |
17560610
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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 |
Structural/Functional materials
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| Research Institution | Tohoku University |
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Principal Investigator |
KOYAMA Keiichi Tohoku University, Institute for Materials Research・Tohoku University, Associate Professor (70302205)
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| Project Period (FY) |
2005 – 2007
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| Keywords | high magnetic field / powder X-ray diffraction / crystal structure / magnetic refrigerant / lst-order phase transition / magnetocaloric effect / structural transformation |
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| Research Abstract |
In this work, I have studied novel magnetic refrigerants by high X-ray diffraction measurements. I have clarified some topics as follows:
1. I observed a field-induced magnetic and structural transition on large magnetocaloric material MnFeP_0.5As_0.5. The material has a hexagonal structure and shows that the parameters a and c deform by 0.5% and 1.0%, respectively, by magnetic field.
2. Large magnetocaloric material Gd_5(GeFe)Si_2 shows a structural transformation from a monoclinic structure to an orthorhombic structure by high magnetic field.
3. I observed a field-induced reverse martensitic transformation from an orthorhombic structure to a cubic structure in large magnetocaloric material Ni_<50>Mn_<36>Sn_<14>.
4. The ferromagnetic shape memory alloy Ni_<50>Mn_<36>Sn_<14> shows a large magnetoresistance effect accompanied by the field-induced reverse martensitic transformation.
5. I revealed the magnetic and thermoelectric properties of magnetic shape memory alloy Ni_<50>Mn_<36>Sn_<14> in high magnetic fields.
6. I observed a metamagnetic (1st-order) transition of MnBi at high temperature of 630 K by high magnetic fields.
7. MnBi shows a large magnetocaloric effect at the 1st-order magnetic transition temperature. By applying high magnetic field, the 1st-order magnetic transition temperature of MnBi increases at the rate of 2 KT^<-1>.
8. Magnetic field and pressure induced magnetic transitions were observed in DyB_2C_2 below 10 K.
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Research Products
(87 results)
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[Presentation] Physical properties of ferromagnetic shape memory alloy Ni-Mn, X (X=Sn, In) in high magnetic fields2007
Author(s)
K. Koyama, H. Okada, K. Watanabe, Y. Yasuda, T. Kanomata, R. Kainuma, W. Ito, K. Oikawa, K. Ishida
Organizer
The Japan Institute of Metals
Place of Presentation
Narashino, Japan
Year and Date
20070327-29
Description
「研究成果報告書概要(欧文)」より
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