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Nitrogenation of La_(0.5)Pr_(0.5)Fe_(11.4)Si_(1.6) with a particle size of 100-150 μm was performed in a high-purity N_2atmosphere of 40 MPa.La_(0.5)Pr_(0.5)Fe_(11.4)Si_(1.6)N_(0.3) nitrogenated at 480 ℃ exhibits an increase in the Curie temperature T_C from 187 to 195 K.Moreover,for a field change from 0 to 1.5 T,the maximum hysteresis loss at T_C is remarkably reduced from 53 to 3 J kg~(-1) and a large magnetic-entropy change △S_m of over 10 J kg~(-1) K~(-1) is maintained.For a La_(0.5)Pr_(0.5)-Fe_(11.4)Si_(1.6)N_(1.2) sample,nitrogenated at 550 ℃,the XRD pattern clearly exhibits two 1:13 phases and,accordingly,the thermal magnetic curves exhibit two transitions,at 210 and at 295 K.The two transitions lead,for a field change of 5 T,to a △S_m larger than 2 J kg~(-1) K~(-1) over a large temperature range from 200 to 310 K with a maximum value of5.3 J kg~(-1) K~(-1) at 225 K.Upon further increase in the nitrogenation temperature to 650 ℃,the amount of the nitrogenpoor phase strongly decreases and a large amount of α-Fe precipitates,resulting in a large reduction in the MCE.
(0.5) Pr_ (0.5) Fe_ (11.4) Si_ (1.6) with a particle size of 100-150 μm was performed in a high-purity N_2atmosphere of 40 MPa.La_ (0.5) Pr_ (0.5) Fe_ ) Si - (1.6) N - (0.3) nitrogenated at 480 ℃ exhibits an increase in the Curie temperature T_C from 187 to 195 K. Moreover, for a field change from 0 to 1.5 T, the maximum hysteresis loss at T_C is remarkably reduced from 53 (0.5) Pr_ (0.5) -Fe_ (1) and a large magnetic-entropy change △ S_m of over 10 J kg -1 K -1 was maintained. For a La 0.5 11.4) Si 1.6 N 1.2 (1.2) sample, nitrogenated at 550 ° C, the XRD pattern clearly exhibits two 1:13 phases and, accordingly, the thermal magnetic curves exhibit two transitions, at 210 and at 295 K. The two transitions lead , for a field change of 5 T, to a ΔS_m larger than 2 J kg -1 K -1 over a large temperature range from 200 to 310 K with a maximum value of 5.3 J kg ~ (- -1) K ~ (-1) at 225 K. When further increase in the nitrogenation temperature to 650 ℃, the amount of the nitrogenpoor phase s trongly decreases and a large amount of α-Fe precipitates, resulting in a large reduction in the MCE.