Effect of substitution of Co for Fe on the magnetic hysteresis loss and the refrigerant capacity in the La_(0.5)Pr_(0.5)Fe_(11.5)Si_(1.5) compounds

摘要

Magnetic hysteresis loss and refrigerant capacity of the NaZn_(13)-type La_(0.5)Pr_(0.5)Fe_(11.5-x)Co_x-Si_(1.5) (0 < = x < = 1.0) compounds have been investigated. The substitution of Co in the La_(0.5)Pr_(0.5)Fe_(11.5)Si_(1.5) causes the order of phase transition at T_C 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 T_C also reduces remarkably from 94.8 J/kg for x=0 to 1.8 J/kg 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 J/kg for a field change of 0-5 T as x varies from 0 to 1.0.