Effect of Particle Size on the Hysteretic Behavior and Magnetocaloric Effect of La0.5Pr0.5Fe11.4Si1.6Compound

Bulk La0.5Pr0.5Fe11.4Si1.6compound exhibits a large magnetic-entropy change ΔSmof 28.1 J/(kg K) for a magnetic-field change from 0 to 1.5 T at the Curie temperature, TCof 186 K, accompanied by a large magnetic hysteresis of 56 J/kg and a noticeable thermal hysteresis of about 1 K. If the bulk sample is ground into middle-size particles (30–60 μm), then the thermal hysteresis is almost eliminated and the magnetic hysteresis loss is decreased by 29%, while the large ΔSmmaintains. Especially, fine powder with an average size of 2 μm shows the same TCas the bulk and does not lose stability. Meanwhile, a comparatively large ΔSmof 13.9 J/(kg K) and a hysteresis reduction of 70% are attained. The hysteresis reduction can be ascribed to the decrease of internal strains and to the improvement of heat transfer due to the increase of the ratio of the surface area to the volume.