DSpace at VNU: The substitution effect of Cr about large magnetocaloric effect in amorphous Fe-Si-B-Nb-Au ribbons

ARTICLE IN PRESS Journal of Magnetism and Magnetic Materials 300 (2006) e385–e387 www.elsevier.com/locate/jmmm The substitution effect of Cr about large magnetocaloric effect in amorphous Fe–Si–B–Nb–Au ribbons S.G Mina, L.G Ligayb, K.S Kima,c, S.C Yua,Ã, N.D Thod, N Chaud a Department of Physics, Chungbuk Nat’l University, Cheongju, 361-763 Korea Department of Physics, Nat’l University, of Uzbekistan, Tashkent 700-174 Uzbekistan c Basic Science Research Institute, Chungbuk Nat’l University, Cheongju, 361-763, Korea d Center for Materials Science, Department of Physics, Hanoi University of Science, 334 Nguyen Trai, Hanoi, Vietnam b Available online 16 November 2005 Abstract The magnetization behaviors have been analyzed for amorphous Fe73.5ÀxCrxSi13.5B9Nb3Au1(x ¼ 0, 3, 5) alloys An amorphous phase was formed after quenching by melt spinning with a copper wheel surface speed of 30 m/s The structure analysis of as-cast was performed using X-ray diffractometer The magnetic properties of the ribbons were measured by VSM The Curie temperature is decreased from 629 to 491 K with increasing Cr concentration (x ¼ 025) Temperature dependence of the entropy variation DSM was calculated from the isothermal magnetization The maximum of DSM was found to appear in the vicinity of the Curie temperature of the amorphous phase The DSM value is 1.7, 1.13 and 0.94 J/kg K at x ¼ 0, 3, and 5, respectively r 2005 Published by Elsevier B.V Keywords: Magnetocaloric effect; Isothermal magnetization; Amorphous ribbon Introduction The temperature change of a magnetic material, associated with an external magnetic field change in an adiabatic process, is defined as the magnetocaloric effect (MCE) The thermal effect was discovered in 1881 by Warburg when he applied varying magnetic field to metal iron [1] Debye and Giauque explained the nature of MCE later and suggested achieving an ultralow temperature by adiabatic demagnetization cooling [2,3] MCE is intrinsic later and suggested achieving an ultralow temperature by adiabatic demagnetization cooling [2,3] MCE is intrinsic to magnetic solids and is induced via the coupling of the magnetic sublattice with the magnetic field, which alters the magnetic part of the total entropy due to a corresponding change in the magnetic field It can be measured and/or calculated as the adiabatic temperature change DT ad ðT; DHÞ, or as the isothermal magnetic entropy change DS M ðT; DHÞ [4–6] The MCE is a function of both temperature T and the ÃCorresponding author Tel.: +82 43 261 2269; fax: +82 43 265 6416 E-mail address: scyu@chungbuk.ac.kr (S.C Yu) 0304-8853/$ - see front matter r 2005 Published by Elsevier B.V doi:10.1016/j.jmmm.2005.10.125 magnetic field change DH and is usually recorded as a function of temperature at a constant DH Recently, a search for new magnetic materials, which exhibit a significant change in the magnetic entropy in response to the change of magnetic field under isothermal conditions, has become an important task in applied physics Traditionally, diluted paramagnetic slats and rare earth intermetallic compounds that display significant MCE were considered as attractive materials for cryogenic applications [4,5] In our work, magnetization and MCE of Fe73.5ÀxCrxSi13.5B9Nb3Au1(x ¼ 0, 3, 5) compounds were investigated These kind of amorphous materials have many useful properties that are attractive for application as magnetic refrigerants Experiments The soft magnetic ribbons Fe73.5ÀxCrxSi13.5B9Nb3Au1 (x ¼ 0, 3, 5) alloys have been prepared by rapid quenching technology on a single copper wheel The linear speed of the copper wheel was 30 m/s The ribbon had the width of mm and the thickness of 16.8 mm The structure analysis ARTICLE IN PRESS S.G Min et al / Journal of Magnetism and Magnetic Materials 300 (2006) e385–e387 of ribbons was performed using X-ray diffractometer Bruker 5005 using Cu-Ka radiation The thermal transition was examined by SDT 2960 TA Instrument The magnetic properties of the ribbon were measured by VSM According to thermodynamic theory, the magnetic entropy change caused by the variation of the external magnetic field from to H max is given by  Z H max  qS dH (1) DS M ¼ qM T From Maxwell’s thermodynamic relationship:     qM qS ¼ qT H qH T Eq (1) can be rewritten as follows:  Z H max  qM dH DS M ¼ qT H (2) (3) Numerical evaluation of the magnetic entropy change was carried out from formula (3) using isothermal magnetization measurements at small discrete field and temperature intervals DS M can be computed approximately from Eq (3) by X M i M iỵ1 jDSM j ẳ DH (4) T iỵ1 T i i Thus, the magnetic entropy changes associated with applied field variations can be calculated from Eq (4) Results and discussion It is known that the favorable soft magnetic properties of Fe-based nanocrystalline alloys come from extremely small magnetic anisotropy and magnetostriction due to small grain size For this purpose, much work has been done on the Fe-based amorphous alloys by annealing process for very good soft magnetic properties Among the nanocrystalline materials, conventional Fe–Nb–Cu–Si–B type (FINEMET) alloys were reported to exhibit excellent soft magnetic properties with a high saturation magnetization and a high permeability [6,7] Especially, appropriate substitution of Cr and Au in the FINEMET systems improved coercive force and core loss at high frequency even in amorphous state [8,9] For the above reasons, the devitrification process of the studied alloy is analogous to that of the usual amorphous Fe–Cr–Si–B–Nb–Au type materials In order to gain further insight into the MCE of the Fe73.5ÀxCrxSi13.5B9Nb3Au1 (x ¼ 0, 3, 5) alloys, we have carried out magnetization studies It takes place in two main stages, as evidenced by the two well-resolved exothermal peaks in the DSC curve The first exotherm corresponds to the appearance of the (Fe,Si) crystals which remain embedded in the remaining amorphous matrix The second crystallization process is related to the formation of boride-type phases and recrystallization phenomena[10,11] The influence of the presence of Cr on the devitrification process is an enhancement of the stability of the alloy against crystallization, as observed in the increase of $40 K in the peak temperature of the first exothermal maximum Fig shows the temperature dependence of low-field magnetization for the samples The Curie temperature, T c was found to be 629, 545 and 491 K for x ¼ 0, and of Fe73.5ÀxCrxSi13.5B9Nb3Au1, respectively With an increase of the concentration of Cr for Fe73.5ÀxCrxSi13.5B9Nb3Au1 system, the Curie temperature decreases According to Franco et al [11], with increasing Cr concentration, thermal stability is enhanced and Curie temperature is reduced, due to the reduce in coupling between the nanocrystals in amorphous matrix Isothermal M2H curves have been measured at various temperatures in the vicinity of Curie temperature (see the top panel of Fig 2) To determine the type of the phase transition for Fe73.5Si13.5B9Nb3Au1, the measured data for the M2H isotherms were transferred into H=M vs M plots and displayed in the bottom panel of Fig According to the Banerjee criterion, the negative slope in H=M vs M plots means that the ferromagnetic (FM) to paramagnetic (PM) phase transition is of first order [12] For the Fe73.5Si13.5B9Nb3Au1, the negative slopes in the temperature region 626–668 K are clearly seen in the lower M region, implying that Fe73.5Si13.5B9Nb3Au1 belongs to the materials displaying a first-order transition In evaluating the magnetocaloric properties of the Fe73.5ÀxCrxSi13.5B9Nb3Au1 (x ¼ 0, 3, 5) samples, the magnetic entropy change, a function of temperature, and magnetic field, produced by the variation of the magnetic field from to H max is calculated by Eq (4) [13], DS M vs T for the all samples, was plotted in Fig As can be seen in Fig 3, with a magnetic field varying from to 1.5 T, the magnetic entropy change DS M reaches a maximum value of about 1.7 J/kg K for x ¼ at 629 K, while DS M is about 70 60 Magnetization (emu/g) e386 50 40 30 20 Fe73.5-xCrxSi13.5B9Nb3Au1 10 350 x=0 x=3 x=5 Hdc= 50 Oe 400 450 500 550 Temperature (K) 600 650 Fig Temperature dependence of the magnetization measured at 50 Oe for Fe73.5ÀxCrxSi13.5B9Nb3Au1 (x ¼ 0, 3, 5) ARTICLE IN PRESS S.G Min et al / Journal of Magnetism and Magnetic Materials 300 (2006) e385–e387 574 579 584 589 594 599 602 605 608 611 614 617 620 623 626 629 632 635 638 643 648 653 658 663 668 60 40 20 1.8 1.6 ∆ SM J/Kg K Magnetization (emu/g) 80 H/M (Oe g/emu) 1200 574 579 584 589 594 599 602 605 608 611 614 617 620 623 626 629 632 A 635 a 638 643 648 653 658 663 668 Fe73.5-xCrxSi13.5B9Nb3Au1 x=0 1000 800 600 400 200 0 1000 2000 3000 4000 M2 (emg/g)2 5000 6000 Fig Top panel: Isothermal magnetization curves in the vicinity of Curie temperature for Fe73.5Si13.5B9Nb3Au1 Bottom panel: The H=M vs M plots for the isotherms of Fe73.5Si13.5B9Nb3Au1 x=0 x=3 x=5 1.2 ∆ H =1.5T 1.0 0.8 0.2 440 460 480 500 520 540 560 580 600 620 640 660 680 Temperature (K) Fig Temperature dependence magnetic entropy obtained under a field change from to 1.5 T, for x ¼ 0, 3, of Fe73.5ÀxCrxSi13.5B9Nb3Au1 (x ¼ 0, 3, 5) Acknowledgement This work was supported by Korea science and Engineering Foundation through the Research Center for Advanced Magnetic Materials at Chungnam National University References [1] [2] [3] [4] 1.13, 0.94 J/kg K for x ¼ 3, at 545 and 491 K (the Curie temperature), respectively [5] Conclusion [7] [8] The magnetic properties and entropy changes of Fe73.5ÀxCrxSi13.5B9Nb3Au1 (x ¼ 0, 3, 5) amorphous alloys were investigated The Curie temperature and the maximum value entropy change decreases with increasing Cr concentration, and the peaks of entropy change appear at the Curie temperature region The maximum value of entropy change decreases with increasing Cr concentration Our results show that these amorphous samples are useful for application as magnetic refrigerants 1.4 0.4 2000 4000 6000 8000 10000 12000 14000 16000 Magnetic Field (Oe) 1400 Fe73.5-xCrxSi13.5B9Nb3Au1 0.6 0 e387 [6] [9] [10] [11] [12] [13] E Warburg, Ann Phys 13 (1881) 141 P Debye, Ann Phys 81 (1926) 1154 W.F Giauque, J Am Chem Soc 49 (1927) 1864 V.K Pecharsky, K.A Gschneidner Jr., J Appl Phys 86 (1) (1999) 565 M Foăldea`ki, R Chahine, T.K Bose, J Appl Phys 77 (7) (1995) 3528 Y Yoshizawa, S Oguma, K Yamauchi, J Appl Phys 64 (1988) 6044 T Sawa, Y Takahashi, J Appl Phys 67 (1990) 5565 V Franco, C.F Conde, A Conde, L.F Kiss, T Keme´ny, IEEE Trans Magn 38 (5) (2002) 3069 V Franco, C.F Conde, A Conde, J Magn Magn Mater 203 (1999) 60 V Franco, C.F Conde, A Conde, J Magn Magn Mater 203 (1999) 60 V Franco, C.F Conde, A Conde, L.F Kiss, T Keme´ny, IEEE Trans Magn 38 (5) (2002) 3069 S.K Banerjee, Phys Lett 12 (1964) 16 S Chaudhary, V.S Jumar, S.B Roy, P Chaddah, S.R Krishnakumar, V.G Sathe, A Kumar, D.D Sarma, J Magn Magn Mater 202 (1999) 47  ... remaining amorphous matrix The second crystallization process is related to the formation of boride-type phases and recrystallization phenomena[10,11] The in uence of the presence of Cr on the. .. devitrification process is an enhancement of the stability of the alloy against crystallization, as observed in the increase of $40 K in the peak temperature of the first exothermal maximum Fig shows the. .. temperature is reduced, due to the reduce in coupling between the nanocrystals in amorphous matrix Isothermal M2H curves have been measured at various temperatures in the vicinity of Curie temperature