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 (TC), the magnetic entropy change (ΔSM) 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 TC and an increase in ΔSM; however, the introduction of interstitial C atoms can adjust TC 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 ΔSM for La0.8Ce0.2Fe11.5Si1.5C0.2 is found to be -28 J/kg K at TC=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 TC and MCEs can be achieved simultaneously in the La1-xCexFe11.5Si1.5Cy compounds by adjusting the concentrations of Ce and C atoms appropriately. - Highlights: → Partial replacement of La with Ce leads to decrease in TC and an increase in ΔSM. → Introduction of interstitial C atoms can adjust TC to high temperature. → Carbonization results in reduction of both hysteresis loss and MCE. → Two different approaches used to evaluate the effective refrigerant capacities. → Enhancements of both TC and MCEs can be achieved simultaneously.