Reduction of hysteresis losses in the magnetic refrigerant La(0.8)Ce(0.2)Fe(11.4)Si(1.6) by the addition of boron

Abstract

In an effort to improve the magnetocaloric effects of the NaZn13-type La0.8Ce0.2Fe11.4Si1.6 compound, the effect of boron doping on the magnetic properties and magnetocaloric properties has been investigated. The magnetic entropy change (Delta S-M) for the La0.8Ce0.2Fe11.4Si1.6 compound, obtained for a field change of 0-5 T using the Maxwell relation exhibits a spike and appears to be overestimated and is thus corrected by using the Clausius-Clapeyron equation (CC). The Delta S-M determined from the CC equation is estimated to be 19.6 J kg(-1) K-1. However, large hysteretic losses which are detrimental to the magnetic refrigeration efficiency occur in the same temperature range. In this work, we report a significant reduction in hysteretic losses by doping the La0.8Ce0.2Fe11.4Si1.6 compound with a small amount of boron to obtain La0.8Ce0.2Fe11.4Si1.6Bx compounds. The hysteresis loss decreases from 131.5 to 8.1 J kg(-1) when x increases from 0 to 0.3, while Delta S-M, obtained for a field change of 0-5 T, varies from 19.6 to 15.9 J kg(-1) K-1. This also simultaneously shifts the T-C from 174 to 184 K and significantly improves the effective refrigerant capacity (RCeff) of the material from 164 to 305 J kg(-1).(C) 2011 American Institute of Physics. [doi: 10.1063/1.3565401]