Nitrogenation of La0.5Pr0.5Fe11.4Si1.6 with a particle size of 100-150 μm was performed in a high-purity N2 atmosphere of 40 MPa. La0.5Pr0.5Fe11.4Si1.6N0.3 nitrogenated at 480 ℃ exhibits an increase in the Curie tem...Nitrogenation of La0.5Pr0.5Fe11.4Si1.6 with a particle size of 100-150 μm was performed in a high-purity N2 atmosphere of 40 MPa. La0.5Pr0.5Fe11.4Si1.6N0.3 nitrogenated at 480 ℃ exhibits an increase in the Curie temperature Tc from 187 to 195 K. Moreover, for a field change from 0 to 1.5 T, the maximum hysteresis loss at Tc is remarkably reduced from 53 to 3 J kg^-1 and a large magnetic-entropy change ASm of over 10 J kg^-1 K^-1 is maintained. For a La0.5Pr0.5- Fe11.4Si1.6N1.2 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 ASm 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. Upon further increase in the nitrogenation temperature to 650 ℃, the amount of the nitrogen- poor phase strongly decreases and a large amount of α-Fe precipitates, resulting in a large reduction in the MCE.展开更多
基金financially supported by the Liaoning Provincial Natural Science Foundation(No.2013020105)the Shenyang Science and Technology Foundation(No.F13-3161-39)
文摘Nitrogenation of La0.5Pr0.5Fe11.4Si1.6 with a particle size of 100-150 μm was performed in a high-purity N2 atmosphere of 40 MPa. La0.5Pr0.5Fe11.4Si1.6N0.3 nitrogenated at 480 ℃ exhibits an increase in the Curie temperature Tc from 187 to 195 K. Moreover, for a field change from 0 to 1.5 T, the maximum hysteresis loss at Tc is remarkably reduced from 53 to 3 J kg^-1 and a large magnetic-entropy change ASm of over 10 J kg^-1 K^-1 is maintained. For a La0.5Pr0.5- Fe11.4Si1.6N1.2 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 ASm 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. Upon further increase in the nitrogenation temperature to 650 ℃, the amount of the nitrogen- poor phase strongly decreases and a large amount of α-Fe precipitates, resulting in a large reduction in the MCE.
