Berlin 2008 – scientific programme
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MA: Fachverband Magnetismus
MA 10: Magnetic Materials
MA 10.11: Talk
Monday, February 25, 2008, 17:45–18:00, H 1028
Effect of hydrostatic pressure on the magnetic and magnetocaloric properties of La(Fe,Si)13-type alloys — •Julia Lyubina, Konstantin Nenkov, Kalyan Mandal, Oliver Gutfleisch, and Ludwig Schultz — IFW Dresden, Institute for Metallic Materials, Helmholtzstr. 20, 01069 Dresden, Germany
The magnetic refrigeration based on the magnetocaloric effect (MCE) is becoming a promising technology to replace the conventional gas-compression/expansion technique. The MCE is the emission or absorption of heat in response to a changing magnetic field and is present in all magnetic materials. A very promising magnetic refrigerator is the La(Fe,Si)13 compound, as it shows a giant MCE near room temperature due to a first-order magnetic phase transition. Among important advantages of LaFe13−xSix alloys are the reduced hysteresis in melt-spun ribbons[1], the abundance of main constituents and the possibility of adjusting the Curie point Tc by varying x and/or by hydrogenation [2]. In this work, LaFe11.8Si1.2 and LaFe11.6Si1.4 alloys prepared by melt-spinning and subsequent annealing at 1000 ∘C/1 h have been studied. The effect of hydrostatic pressure up to 10 kbar on the Curie temperature and itinerant electron metamagnetic transition has been investigated. On applying pressure, a shift of Tc to lower temperatures at a rate of 13 K/kbar is observed. Moreover, it leads to a gradual change from the first- to second-order-type transition. The influence of pressure on the MCE is discussed. [1] O. Gutfleisch et al., J. Appl. Phys. 97 (2005) 10M305. [2] K. Mandal et al., J. Magn. Magn. Mater. 290-291 (2005) 673.