High performance Sm-Co powders obtained by crystallization from ball milled amorphous state

doi:10.1016/j.jmst.2019.04.041

Abstract

Abstract:

Isotropic Sm-Co nanoparticle powders with high coercivity were prepared by high-energy ball milling followed by optimal annealing at different temperatures. The covercivity increased monotonically with increasing of the annealing temperature and a highest coercivity of 31.2 kOe was obtained. The sample with an optimal energy product of 17.0 MGOe still had a coercivity of 18.2 kOe. The evolution of phase, particle size, mechanism of coercivity and other related magnetic properties were analyzed. The excellent performance is attributed to nanoscale size grains below 15 nm and good exchange coupling between nanoparticles.

Key words: Sm-Co, Nanoparticles, High-energy ball milling, Post-annealing, Coercivity

Jinkui Fan, Qiang Zheng, Rui Bao, Jianhong Yi, Juan Du. High performance Sm-Co powders obtained by crystallization from ball milled amorphous state[J]. J. Mater. Sci. Technol., 2020, 37: 181-184.

Figures/Tables 7

Fig. 1. XRD patterns of SmCo5 powders annealed at different temperatures in the range of 450-750?°C for 30?min.

Fig. 2. Average grain size of annealed SmCo5 powders at different temperatures.

Fig. 3. Demagnetizaton curve (a) and coercivity (b) of powders annealed at 450-750?°C for 30?min.

Table 1 Saturation magnetization Ms, Remanence Mr, Remanence ratio Mr/Ms, Coercivity Hc, Maximum magnetic energy product (BH)max measured at 300?K.

	450?°C	500?°C	550?°C	600?°C	650?°C	700?°C	750?°C
M_s (emu/g)	108.9	99.4	97.4	91.9	87.5	79.3	76.0
M_r (emu/g)	79.7	75.8	70.7	66.6	62.9	55.0	51.9
M_r/M_s	0.732	0.763	0.726	0.724	0.719	0.694	0.683
H_c (kOe)	18.2	19.7	25.5	26.1	28.5	30.6	31.2
(BH)_max (MGOe)	17.0	15.9	14.0	12.5	11.2	8.6	7.6

Fig. 4. Initial magnetization curves for powders annealed at different temperatures for comparison.

Fig. 5. Slope (dM/dH) of initial magnetization curves (a) and the pinning field (b) of powders annealed at different temperatures. The slope of initial magnetization curves for powders annealed at 700°C and 75?°C is shown as an inset in Fig. 5(a).

Fig. 6. Maximum magnetic energy product (BH)max and the ratio of Mr/Ms for the powders annealed at different temperatures.

References

[1]	P. Saravanan, M. Manivel Raja, R. Gopalan, N.V. Rama Rao, K. Suresh, D.V. Sridhara Rao, V. Chandrasekaran, Intermetallics 16 (2008) 636-641.
[2]	M. Yue, C.L. Li, Q. Wu, Z.H. M, H.H. X, S. Palaka, Chen. Eng. J. 343(2018) 1-7.
[3]	K.J. Strnat, E.P. Wohlfarth, K.H. Buschow, Ferromagnetic Materials, Elsevier, Amsterdam, 1988, pp. 131, 4.
[4]	G.C. Hadjipanayis, Rare-Earth Iron Permanent Magnets, Clarendon Press, Oxford. 1996, pp. 286.
[5]	W.G.D. Frederick, M. Hoch, IEEE Trans. Magn. 11(1975) 1434-1436.
[6]	J.M.D. Coey, Solid State Commun. 102(1997) 101-105.
[7]	K. Kumar, D. Das, E. Wettstein, J. Appl. Phys. 49(1978) 2052-2054.
[8]	Y. Liu, M.P. Dallimore, P.G. McCormick, J. Magn.Magn. Mater. 116(1992) L320-L324.
[9]	Z.H. Ma, M. Yue, Q. Wu, C.L. Li, Y.S. Yu, Nanoscale 10 (2018) 10377-10382.
[10]	B. Shen, C. Yu, A.A. Baker, S.K. McCall, Y.S. Yu, D. Su, Z.Y. Yin, H. Liu, J.R. Li, S.H. Sun, Angew. Chem. Int. Ed. 57(2018) 1-6.
[11]	C.K. Mylvganam, P. Gaunt, Philos. Mag. B 44 (1981) 581-593.
[12]	J. Ding, P.A.I. Smith, P.G. McCormick, R. Street, J. Magn. Magn. Mater. 161(1996) 303-308.
[13]	J. Ding, P.G. McCornmick, R. Street, J.Alloys. Compd. 191(1993) 197-201.
[14]	J. Ding, Y. Liu, P.G. McCormick, R. Street, J.Magn. Magn. Mater. 123(1993) L239-L242.
[15]	L. Zheng, B. Cui, N.G. Akdogan, W. Li, G.C. Hadjipanayis, J. Alloys. Compd. 504(2010) 391-394.
[16]	C.H. Chen, S.J. Knutson, Y. Shen, R.A. Wheeler, J.C. Horwath, P.N. Barnes, Appl. Phys. Lett. 99(2011), 012504.
[17]	Y. Wang, Y. Li, C. Rong, J.P. Liu, Nanotechnology 18(2007), 465701.
[18]	L.D. Liu, S.L. Zhang, J. Zhang, J. Magn. Magn. Mater. 374(2015) 108-115.
[19]	G.C. Hadjipanayis, J. Magn. Magn. Mater. 200(1999) 373-391.
[20]	C.B. Jiang, M. Venkatesan, K. Gallagher, J.M.D. Coey, J. Magn. Magn. Mater. 236(2001) 49-55.
[21]	I.A. AI-Omari, J. Shobaki, R. Skomski, D. Leslie-Pelecky, J. Zhou, D.J. Sellmyer, Physica B 321 (2002) 107-111.
[22]	Q. Yao, W. Liu, X.G. Zhao, D. Li, Z.D. Zhang, J. Appl. Phys. 99(2006), 053905.
[23]	Y. Ma, X. Yin, B. Shao, Q. Yang, Q. Shen, X. Zhou, J. Sun, D. Guo, K. Li, J. Mater. Sci. 54(2019) 2658-2667.
[24]	P. Saravanan, A.N. Sharma, V. Chandrasekaran, J. Magn. Magn. Mater. 321(2009) 3138-3143.
[25]	H. Fukunaga, H. Inoue, Jpn. J. Appl. Phys. 31(1992) 1347-1352.