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Strong textured SmCo5 nanoflakes with ultrahigh coercivity prepared by multistep (three steps) surfactant-assisted ball milling.

Zuo WL, Zhao X, Xiong JF, Zhang M, Zhao TY, Hu FX, Sun JR, Shen BG - Sci Rep (2015)

Bottom Line: The high coercivity of 26.2 kOe for SmCo5 nanoflakes are obtained by multistep (three steps) surfactant-assisted ball milling.The magnetic properties, phase structure and morphology are studied by VSM, XRD and SEM, respectively.The results demonstrate that the three step ball-milling can keep more complete crystallinity (relatively less defects) during the process of milling compared with one step high energy ball-milling, which enhances the texture degree and coercivity.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Magnetism, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, People's Republic of China.

ABSTRACT
The high coercivity of 26.2 kOe for SmCo5 nanoflakes are obtained by multistep (three steps) surfactant-assisted ball milling. The magnetic properties, phase structure and morphology are studied by VSM, XRD and SEM, respectively. The results demonstrate that the three step ball-milling can keep more complete crystallinity (relatively less defects) during the process of milling compared with one step high energy ball-milling, which enhances the texture degree and coercivity. In addition, the mechanism of coercivity are also studied by the temperature dependence of demagnetization curves for aligned SmCo5 nanoflakes/resin composite, the result indicates that the magnetization reversal could be controlled by co-existed mechanisms of pinning and nucleation.

No MeSH data available.


Related in: MedlinePlus

(a) The demagnetization curves of SmCo5 powders with the BM time from 0 to 32 h. (b) The coercivity Hc and remanence ratio Mr/Ms dependence on BM time.
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f1: (a) The demagnetization curves of SmCo5 powders with the BM time from 0 to 32 h. (b) The coercivity Hc and remanence ratio Mr/Ms dependence on BM time.

Mentions: Figure 1(a) shows the demagnetization curves of SmCo5 powders with the BM time from 0 to 32 h. The coercivity Hc and remanence ratio Mr/Ms dependence on BM time are also shown in the Fig. 1(b). It can be seen that both the Hc and Mr/Ms show a sharp increase in the initial stage of BM (time ≤ 4 h), which is mainly attributed to the grain refinement. This result demonstrates that the low-energy (30 V, 150 rpm) is effective in the grain refinement especially for the initial stage of BM. With increasing the BM time and energy, Hc only shows a smooth increase and reaches a maximum value of 26.2 kOe after 24 h, which is the maximum value of coercivity for the reported rare earth permanent magnetic nanoflakes, and even higher than Tb-Fe-B15. Meanwhile, the decline in increase rate of coercivity can be due to the brittleness decreases and ductility increases, which lead to the decrease of grain refinement efficiency when the particle size decreases into nano-scaled56. In the end, the slight decrease of coercivity for BM 28 h indicates that the BM energy could not need to further improve. To the contrary, the Mr/Ms shows a monotonous decrease when the BM time is larger than 4 h, this phenomenon is normal and owing to multi-factor. Such as, the increase fraction of small polycrystalline nanoflakes and nanoparticles which incline to random orientation and incoherence in grain boundaries10, the decrease uniaxial (00l) texture due to the plastic deformation11. The decrease of Mr/Ms also indicates that the high energy is harmful for forming strong textured nanoflakes. Therefore, in this paper, the maximum BM energy is no longer increase and fixed as 50 V (about 250 rpm).


Strong textured SmCo5 nanoflakes with ultrahigh coercivity prepared by multistep (three steps) surfactant-assisted ball milling.

Zuo WL, Zhao X, Xiong JF, Zhang M, Zhao TY, Hu FX, Sun JR, Shen BG - Sci Rep (2015)

(a) The demagnetization curves of SmCo5 powders with the BM time from 0 to 32 h. (b) The coercivity Hc and remanence ratio Mr/Ms dependence on BM time.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4536656&req=5

f1: (a) The demagnetization curves of SmCo5 powders with the BM time from 0 to 32 h. (b) The coercivity Hc and remanence ratio Mr/Ms dependence on BM time.
Mentions: Figure 1(a) shows the demagnetization curves of SmCo5 powders with the BM time from 0 to 32 h. The coercivity Hc and remanence ratio Mr/Ms dependence on BM time are also shown in the Fig. 1(b). It can be seen that both the Hc and Mr/Ms show a sharp increase in the initial stage of BM (time ≤ 4 h), which is mainly attributed to the grain refinement. This result demonstrates that the low-energy (30 V, 150 rpm) is effective in the grain refinement especially for the initial stage of BM. With increasing the BM time and energy, Hc only shows a smooth increase and reaches a maximum value of 26.2 kOe after 24 h, which is the maximum value of coercivity for the reported rare earth permanent magnetic nanoflakes, and even higher than Tb-Fe-B15. Meanwhile, the decline in increase rate of coercivity can be due to the brittleness decreases and ductility increases, which lead to the decrease of grain refinement efficiency when the particle size decreases into nano-scaled56. In the end, the slight decrease of coercivity for BM 28 h indicates that the BM energy could not need to further improve. To the contrary, the Mr/Ms shows a monotonous decrease when the BM time is larger than 4 h, this phenomenon is normal and owing to multi-factor. Such as, the increase fraction of small polycrystalline nanoflakes and nanoparticles which incline to random orientation and incoherence in grain boundaries10, the decrease uniaxial (00l) texture due to the plastic deformation11. The decrease of Mr/Ms also indicates that the high energy is harmful for forming strong textured nanoflakes. Therefore, in this paper, the maximum BM energy is no longer increase and fixed as 50 V (about 250 rpm).

Bottom Line: The high coercivity of 26.2 kOe for SmCo5 nanoflakes are obtained by multistep (three steps) surfactant-assisted ball milling.The magnetic properties, phase structure and morphology are studied by VSM, XRD and SEM, respectively.The results demonstrate that the three step ball-milling can keep more complete crystallinity (relatively less defects) during the process of milling compared with one step high energy ball-milling, which enhances the texture degree and coercivity.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Magnetism, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, People's Republic of China.

ABSTRACT
The high coercivity of 26.2 kOe for SmCo5 nanoflakes are obtained by multistep (three steps) surfactant-assisted ball milling. The magnetic properties, phase structure and morphology are studied by VSM, XRD and SEM, respectively. The results demonstrate that the three step ball-milling can keep more complete crystallinity (relatively less defects) during the process of milling compared with one step high energy ball-milling, which enhances the texture degree and coercivity. In addition, the mechanism of coercivity are also studied by the temperature dependence of demagnetization curves for aligned SmCo5 nanoflakes/resin composite, the result indicates that the magnetization reversal could be controlled by co-existed mechanisms of pinning and nucleation.

No MeSH data available.


Related in: MedlinePlus