کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
8157133 | 1524860 | 2014 | 10 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Normal and inverse magnetocaloric effects in the ferromagnetic shape memory alloys
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
فیزیک و نجوم
فیزیک ماده چگال
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
The field-induced entropy change and the magnetocaloric effect (MCE) of the ferromagnetic shape memory alloys Ni2Mn1âxCuxGa and Ni2Mn1+xIn1âx are studied theoretically on the basis of a phenomenological free energy. The free energy is expanded in powers of the mangetization M and the tetragonal distortion e3, which are the order parameters for the ferromagnetic and martensitic transitions, respectively. Through the magneto-structural interaction term in the free energy, magnetic fields can affect also e3 to shift the martensitic first-order transition temperatures. This shift of the transition temperature results in large field-induced changes in the order parameters, which can be responsible for large MCEs. It is found that the resulting MCEs depend on the nature of the magneto-structural interaction. In Ni2Mn1âxCuxGa with the attractive magneto-structural interaction, magnetic fields cause the negative entropy change as in the normal MCE. In Ni2Mn1+xIn1âx with the repulsive interaction, on the other hand, magnetic fields can do the positive entropy change causing the inverse MCE. For both the alloy systems, the x dependences of the refrigerant capacity (RC) are studied to find the compositions optimum for large MCEs. Applicability of the Maxwell relation to the system with the first-order transition is also studied by simulating the field-induced entropy changes on the basis of the Maxwell relation.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Magnetism and Magnetic Materials - Volume 361, June 2014, Pages 34-43
Journal: Journal of Magnetism and Magnetic Materials - Volume 361, June 2014, Pages 34-43
نویسندگان
Mitsuo Kataoka, Takeshi Kanomata, Rie Y. Umetsu, Ryosuke Kainuma,