Controlling of Particle Size to Maximize the Coercivity of SmCo5 Hard Magnet

TY - CONF

T1 - Controlling of Particle Size to Maximize the Coercivity of SmCo5 Hard Magnet

AU - Tang, Hao

AU - Mamakhel, Mohammad Aref Hasen

AU - Christensen, Mogens

PY - 2019/8/28

Y1 - 2019/8/28

N2 - Rare-earth magnets have been widely used for magnetic, electronic, energy applications in the world. Among these strong magnetic matierials, SmCo5 rare-earth hard magnet has the largest anisotropy field, while the coercivity of a magnet is usually less than 30% of its anisotropy field.[1] The coercivity is enhanced, when the grain size (spherical shape) is in the stable single-domain (SSD) range. Theoretical calculation predicts the SSD range of SmCo5 to be 740-870 nm,[2] however, at present, there has been no experimental data supporting the claim. Herein, we used an improved chemical method to synthesize SmCo5 particles with an average particle size (APS) range from 202 nm to 810 nm by tuning the reaction condition of the precursor, named T1, T3, T5, T8, T12, T16 based on reaction time (see Figure 1a). We found that the morphology and composition of the precursor play a significant role in determining the phase composition and APS of the final product. The maximum coercivity of 2632 kA m-1 (33.1 kOe) was obtained when the APS reached 805 nm (Figure 1b). SEM images and recoil loops demonstrate that samples with high coercivity are uniform and the coherent rotation happens during the demagnetization process. Henkel plots and δM plots verify the existing of strong exchange coupling interaction between particles, resulting in the high Mr/Ms ratios. This is the first report on optimizing the coercivity of SmCo5 based on single domain theory and the optimized APS fits very well the predicted SSD range.

AB - Rare-earth magnets have been widely used for magnetic, electronic, energy applications in the world. Among these strong magnetic matierials, SmCo5 rare-earth hard magnet has the largest anisotropy field, while the coercivity of a magnet is usually less than 30% of its anisotropy field.[1] The coercivity is enhanced, when the grain size (spherical shape) is in the stable single-domain (SSD) range. Theoretical calculation predicts the SSD range of SmCo5 to be 740-870 nm,[2] however, at present, there has been no experimental data supporting the claim. Herein, we used an improved chemical method to synthesize SmCo5 particles with an average particle size (APS) range from 202 nm to 810 nm by tuning the reaction condition of the precursor, named T1, T3, T5, T8, T12, T16 based on reaction time (see Figure 1a). We found that the morphology and composition of the precursor play a significant role in determining the phase composition and APS of the final product. The maximum coercivity of 2632 kA m-1 (33.1 kOe) was obtained when the APS reached 805 nm (Figure 1b). SEM images and recoil loops demonstrate that samples with high coercivity are uniform and the coherent rotation happens during the demagnetization process. Henkel plots and δM plots verify the existing of strong exchange coupling interaction between particles, resulting in the high Mr/Ms ratios. This is the first report on optimizing the coercivity of SmCo5 based on single domain theory and the optimized APS fits very well the predicted SSD range.

KW - SmCo5 particles

KW - high coercivity

KW - single-domain size

KW - chemical method

M3 - Poster

T2 - Joint European Magnetic Symposia 2019

Y2 - 26 September 2019 through 30 September 2019

ER -