Journal of the Korean Physical Society

, Volume 60, Issue 7, pp 1049–1051 | Cite as

Heat-treatment effect in Mn0.997Fe0.003As for magnetic refrigeration application

  • Hyun Tae Cho
  • Il Jin Park
  • In-Bo Shim
  • Chul Sung Kim
  • Sam Jin Kim
Research Papers
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Abstract

The structure and the magnetocaloric effect of single-phased Mn0.997Fe0.003As were studied with X-ray diffraction and vibrating sample magnetometry. In the Mn0.997Fe0.003As sample, the firstorder ferromagnetic-to-paramagnetic transition was observed near the Curie temperature (T C ), namely at 308 K for the quenched sample and at 313 K for the slowly-cooled sample. This magnetic transition was accompanied by a structural transition from a hexagonal (NiAs-type) to an orthorhombic (MnP-type) structure. We also observed that after the heat treatment, the sample showed a large change in the magnetocaloric effect depending on the cooling conditions. From the isothermal M-H curves, the changes in the magnetic entropy (−ΔS M ) were determined at temperatures between 280 and 320 K for different magnetic fields. For the sintered samples under slow cooling and water quenching, the maximum magnetic entropy changes at a magnetic field of 1.5 T were 19.6 and 32.2 J/kg K, respectively. Such a significant difference between the maximum entropy changes is due to the degree of the structure distortion, which depends on the heat treatment.

Keywords

Magnetocaloric effect Magnetic entropy Cooling method 
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Copyright information

© The Korean Physical Society 2012

Authors and Affiliations

  • Hyun Tae Cho
    • 1
  • Il Jin Park
    • 1
  • In-Bo Shim
    • 1
  • Chul Sung Kim
    • 1
  • Sam Jin Kim
    • 1
  1. 1.Department of PhysicsKookmin UniversitySeoulKorea

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