Reduction of hysteresis loss and large magnetocaloric effect in the C- and H-doped La(Fe, Si) ₁₃ compounds around room temperature

The effects of the interstitial C and H atoms on the phase formation, the hysteresis loss, and magnetocaloric effects of the NaZn ₁₃-type La(Fe, Si) ₁₃ compounds are investigated. It is found that the annealing time to obtain a 1:13 structure is significantly reduced from 40 days for LaFe _11.7Si _1.3 to a week for LaFe _11.7Si _1.3C _0.2. The introduction of C and H atoms can adjust Curie temperature to around room temperature and leads to the decrease in magnetic entropy change (δS _M) and magnetic hysteresis loss due to the weakening of itinerant-electron metamagnetic transition. Large -δS _M of 19.0 J/kg K at room temperature without hysteresis loss for LaFe _11.7Si _1.3C _0.2H _1.7 is obtained for a field change of 5 T.