Simultaneous enhancements of Curie temperature and magnetocaloric effects in the La1-xCexFe11.5Si1.5Cy compounds

The effects of introducing Ce and C atoms on the Curie temperature (T-C), the magnetic entropy change (Delta S-M) and the hysteresis loss have been investigated in the NaZn13-type LaFe11.5Si1.5 compound. Partial replacement of La with Ce leads to a decrease in T-C and an increase in Delta S-M; however, the introduction of interstitial C atoms can adjust T-C to high temperature. The itinerant-electron metamagnetic transition is weakened after carbonization, which results in a reduction of both the hysteresis loss and magnetocaloric effect (MCE). The maximum value of Delta S-M for La0.8Ce0.2Fe11.5Si1.5C0.2 is found to be -28 J/kg K at T-C=207 K with an effective refrigeration capacity of 420 J/kg for a field change from 0 to 5 T. Our study reveals that the enhancements of both T-C and MCEs can be achieved simultaneously in the La-1 xCexFe11.5Si1.5Cy compounds by adjusting the concentrations of Ce and C atoms appropriately. (C) 2011 Elsevier B.V. All rights reserved.