Enhancement of the refrigerant capacity in low level boron doped La_0.8Gd_0.2Fe_11.4Si_1.6

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• 作者：P. Shamba^a ; ^{ps807@uowmail.edu.au} ; R. Zeng^a ; J.L. Wang^a ; ^b ; ^c ; S.J. Campbell^b ; S.X. Dou^a
• 关键词：Magnetocaloric ; Magnetic property ; Doping ; Alloy ; Intermetallic compound
• 刊名：Journal of Magnetism and Magnetic Materials
• 出版年：2013
• 出版时间：April, 2013
• 年：2013
• 卷：331
• 期：Complete
• 页码：102-108
• 全文大小：1396 K

文摘

The effects of boron doping on the itinerant-electron metamagnetic (IEM) transition and the magnetocaloric effects (MCEs) in the cubic NaZn₁₃-type La_0.8Gd_0.2Fe_11.4Si_1.6 compound have been investigated. The Curie temperature, T_C, of La_0.8Gd_0.2Fe_11.4Si_1.6B_x compounds with x=0, 0.03, 0.06, 0.2 and 0.3 was found to increase from 200 K to 222 K with increase in boron doping, x. The maximum values of the isothermal magnetic entropy change, ¦¤S_M, (derived using the Maxwell relation for a field change ¦¤B=0-5 T) in La_0.8Gd_0.2Fe_11.4Si_1.6B_x with x=0, 0.03, 0.06, 0.2 and 0.3 are 14.8, 16, 15, 7.5 and 6.6 J kg^?1 K^?1 respectively, with corresponding values of the refrigerant capacity, RCP of 285, 361, 346, 222 and 245 J kg^?1. The large ¦¤S_M values observed for the undoped sample, and the low level B doped La_0.8Gd_0.2Fe_11.4Si_1.6B_0.03 and La_0.8Gd_0.2Fe_11.4Si_1.6B_0.06 compounds are attributed to the first order nature of the IEM transition while the decrease of ¦¤S_M at x=0.2 and 0.3 is due to a change in the second order phase transition with increase in B doping. The nature of the magnetic phase transitions is also reflected by the magnetic hysteresis of 3.7, 9, 5.7, 0.4 and 0.3 J kg^?1 for x=0.0, 0.03, 0.06, 0.2 and 0.30 respectively. The possibility of tuning the T_C and the magnetocaloric properties at temperatures close to room temperature make this system interesting from the points of view of both fundamental aspects as well as applications.