Effect of substitution of Co for Fe on the magnetic hysteresis loss and the refrigerant capacity in the La0.5 Pr0.5 Fe11.5 Si1.5 compounds

Magnetic hysteresis loss and refrigerant capacity of the Na Zn13 -type La0.5 Pr0.5 Fe11.5-x Cox Si1.5 (0≤x≤1.0) compounds have been investigated. The substitution of Co in the La0.5 Pr0.5 Fe11.5 Si1.5 causes the order of phase transition at TC to change from first order to second order at x=0.6. Although the magnetic entropy change decreases with increasing Co concentration, the hysteresis loss at TC also reduces remarkably from 94.8 Jkg for x=0 to 1.8 Jkg for x=0.4 because an increase in Co content can weaken the itinerant electron metamagnetic transition. The effective refrigerant capacity remains at a high value ranging from 355 to 433 Jkg for a field change of 0-5 T as x varies from 0 to 1.0.