DPG Phi
Verhandlungen
Verhandlungen
DPG

Dresden 2009 – scientific programme

Parts | Days | Selection | Search | Downloads | Help

MA: Fachverband Magnetismus

MA 14: Poster Ib: Magnetic Materials (1-14); Micro Magnetism/Computational Mag. (15-17); Surface Magnetism (18-22); Spin Structures/Phase Transitions (23-25)

MA 14.11: Poster

Tuesday, March 24, 2009, 10:15–13:00, P1B

Adiabatic temperature change in giant magnetocaloric effect compoundsJulia Lyubina, •Philipp Rosendahl, Jian Liu, Ludwig Schultz, and Oliver Gutfleisch — 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 two parameters, the adiabatic temperature change, ΔTad, and the magnetic entropy change, ΔSM, are used for the evaluation of the MCE [1,2]. Most of the MCE studies are performed by indirect methods, among which the ΔSM calculation using the Maxwell relation is the most widespread. Here, we report on direct adiabatic temperature change ΔTad measurements in giant MCE materials, La(Fe,Si)13- and Ni-Mn-In Heusler-type alloys. ΔTad was measured using a direct contact with a thermocouple in magnetic fields up to 1.93 T produced by a permanent magnet assembly (Halbach cylinder). In Ni50Mn34In16, the maximum ΔTad of 2 K is observed around the Curie temperature of the austenite (317 K), whereas ΔTadmax is -1.3 K near the martensite-austenite transition (181 K). On cooling, i.e. during the austenite-martensite transition, ΔTadmax reduces to about -0.5 K. In LaFe12Si1, the maximum ΔTad reaches -5.4 K at 184 K. The contribution of the latent heat to the adiabatic temperature change during first-order phase transitions is discussed. [1] J. Lyubina et al., J. Magn. Magn. Mater. 320 (2008) 2252; [2] J. Lyubina et al., Phys. Rev. Lett. 101 (2008) 177203.

100% | Mobile Layout | Deutsche Version | Contact/Imprint/Privacy
DPG-Physik > DPG-Verhandlungen > 2009 > Dresden