A facile synthesis of anisotropic SmCo5 nanochips with high magnetic performance

Yue, Ming; Li, Chenglin; Wu, Qiong; Ma, Zhenhui; Xu, Hang; Palaka, Subhashini

doi:10.1016/j.cej.2018.02.060

Cited by 39 publications

(22 citation statements)

References 46 publications

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“…2 c and reveal the main phase in all samples to be SmCo 5 , while a small number of other phases like Sm 2 Co 7 -R (rhombohedral structure), Sm 2 Co 7 -H (hexagonal structure), and Sm 2 Co 17 can be identified for some samples. Often in the literature SmCo 5 is reported to be phase pure based on PXRD collected with Cu radiation (λ = 1.54 Å), this is problematic, because Cu radiation produces strong fluorescence when the sample contains Co and Sm, this strong background can easily hide impurities 8 , 9 , 17 , 22 . Ideally the samples should be measured using Co radiation (λ = 1.78 Å) or at a short wavelength synchrotron source.…”

Section: Resultsmentioning

confidence: 99%

High coercivity SmCo5 synthesized with assistance of colloidal SiO2

Hao

Mamakhel

Christensen

2021

Sci Rep

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SmCo5 is one of the most promising candidates for achieving a hard magnet with a high coercivity. Usually, composition, morphology, and size determine the coercivity of a magnet, however, it is challenging to synthesize phase pure SmCo5 with optimal size and high coercivity. In this paper, we report on the successful synthesis of phase pure SmCo5 with spherical/prolate spheroids shape. Size control is obtained by utilizing colloidal SiO2 as a template preventing aggregation and growth of the precursor. The amount of SiO2 nanoparticles (NPs) in the precursor tunes the average particle size (APS) of the synthesized SmCo5 with particle dimension from 740 to 504 nm. As-prepared pure SmCo5 fine powder obtained from using 2 ml SiO2 suspension possesses an APS of 625 nm and exhibits an excellent coercivity of 2986 kA m−1 (37.5 kOe) without alignment of the particles prior to magnetisation measurements. Comparing with a reference sample prepared without adding any SiO2 NPs, an enhancement of 35% of the coercivity was achieved. The improvement is due to phase purity, stable single-domain (SSD) size, and shape anisotropy originating from the prolate spheroid particles.

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Section: Resultsmentioning

confidence: 99%

High coercivity SmCo5 synthesized with assistance of colloidal SiO2

Hao

Mamakhel

Christensen

2021

Sci Rep

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“…Ethylene glycol and glycerol are potentially usable; however, these chemicals were excluded due to their sluggish reactivity with CaO 33 . Distilled water and dilute acidic solutions ( e.g ., acetic acid, hydrochloric acid (HCl)) have already been widely reported as traditional washing solutions 20 , 21 , 34 . In this study, the use of a strong acid was not considered even if it was largely diluted, as it could lead to the serious corrosion of metal magnetic compounds.…”

Section: Resultsmentioning

confidence: 99%

Near theoretical ultra-high magnetic performance of rare-earth nanomagnets via the synergetic combination of calcium-reduction and chemoselective dissolution

Lee

Hwang

Cho

et al. 2018

Sci Rep

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Rare earth permanent magnets with superior magnetic performance have been generally synthesized through many chemical methods incorporating calcium thermal reduction. However, a large challenge still exists with regard to the removal of remaining reductants, byproducts, and trace impurities generated during the purifying process, which serve as inhibiting intermediates, inducing productivity and purity losses, and a reduction in magnetic properties. Nevertheless, the importance of a post-calciothermic reduction process has never been seriously investigated. Here, we introduce a novel approach for the synthesis of a highly pure samarium-cobalt (Sm-Co) rare earth nanomagnet with near theoretical ultra-high magnetic performance via consecutive calcium-assisted reduction and chemoselective dissolution. The chemoselective dissolution effect of various solution mixtures was evaluated by the purity, surface microstructure, and magnetic characteristics of the Sm-Co. As a result, NH4Cl/methanol solution mixture was only capable of selectively rinsing out impurities without damaging Sm-Co. Furthermore, treatment with NH4Cl led to substantially improved magnetic properties over 95.5% of the Ms for bulk Sm-Co. The mechanisms with regard to the enhanced phase-purity and magnetic performance were fully elucidated based on analytical results and statistical thermodynamics parameters. We further demonstrated the potential application of chemoselective dissolution to other intermetallic magnets.

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“…Besides these, the Sm(Co or Fe)–O NPs with tunable sizes in the range of 60–220 nm and different morphologies were synthesized directly from thermal decomposition of Sm(acac) 3 and Co/Fe(acac) 2 ( Figure 6(b–j) ) [ 74 ] or SmCo–oleate complex ( Figure 6(k–s) ) [ 75 ]. The SmCo–O NPs with various morphologies, such as Sm(OH) 3 –Co nanorods [ 76 ] or urchin-like [ 77 ], Sm(OH) 3 –Co(OH) 2 nanoflakes [ 78 , 79 ], and SmCo–O nanofibers [ 80 , 81 ], could be successfully obtained by sonification [ 76 ], hydro/solvothermal reaction [ 77–79 ], and electrospinning [ 80 , 81 ]. Once the R amounts in these encapsulated nanostructures are under the critical concentration for the solid-solution formation, the R-doped T–O nanostructures can be synthesized by using procedures which are similar to the above [ 81–85 ].…”

Section: Synthesis Of Nanostructured Precursorsmentioning

confidence: 99%

“…10 nm to several hundred nanometers, as shown in Figure 6(t ) [ 98 ]. Monodisperse and size-tunable T/T–O@R–O and RT–O nanostructured precursors with homogeneous composition have opened horizons for optimization of the microstructure of R–T MMPs since they could be embedded in dispersant matrixes (e.g., CaO, graphite oxide GO), as shown in Figure 6(j ) [ 74 , 78 , 79 ], or tightly coated with other layers intact (e.g., CaO, GO, nitrogen-doped graphitic carbon NGC) in core@shell structures, as shown in Figure 6(s ) [ 73 , 75 , 76 ]. While mixed NPs strategy partially succeeded in only the embedding, leading to the limited kinetic control of the microstructure of R–T MMPs [ 88–92 , 100 ].…”

Section: Synthesis Of Nanostructured Precursorsmentioning

confidence: 99%

“…intermetallics, leading to the successful synthesis of some binary R-T MMPs (e.g., [69]; their sizes were tuned from 20 to 200 nm by varying the OA concentration, as shown in Figure 3 as Sm(OH) 3 -Co nanorods [76] or urchin-like [77], Sm(OH) 3 -Co(OH) 2 nanoflakes [78,79], and SmCo-O nanofibers [80,81], could be successfully obtained by sonification [76], hydro/solvothermal reaction [77][78][79], and electrospinning [80,81].…”

Section: Introductionmentioning

confidence: 99%

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Synthesis of mesoscopic particles of multi-component rare earth permanent magnet compounds

Trinh

Kim

Sato

et al. 2021

Science and Technology of Advanced Materials

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Multielement rare earth (R)–transition metal (T) intermetallics are arguably the next generation of high-performance permanent magnetic materials for future applications in energy-saving and renewable energy technologies. Pseudobinary Sm 2 Fe 17 N 3 and (R,Zr)(Fe,Co,Ti) 12 (R = Nd, Sm) compounds have the highest potential to meet current demands for rare-earth-element-lean permanent magnets (PMs) with ultra-large energy product and operating temperatures up to 200°C. However, the synthesis of these materials, especially in the mesoscopic scale for maximizing the maximum energy product ( ), remains a great challenge. Nonequilibrium processes are apparently used to overcome the phase-stabilization challenge in preparing the R–T intermetallics but have limited control of the material’s microstructure. More radical bottom-up nanoparticle approaches based on chemical synthesis have also been explored, owing to their potential to achieve the desired composition, structure, size, and shape. While a great achievement has been made for the Sm 2 Fe 17 N 3 , progress in the synthesis of (R,Zr)(Fe,Co,Ti) 12 magnetic mesoscopic particles (MMPs) and R–T/T exchange-coupled nanocomposites (NCMs) with substantial coercivity ( ) and remanence ( , respectively, remains marginal.

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A facile synthesis of anisotropic SmCo5 nanochips with high magnetic performance

Cited by 39 publications

References 46 publications

High coercivity SmCo5 synthesized with assistance of colloidal SiO2

High coercivity SmCo5 synthesized with assistance of colloidal SiO2

Near theoretical ultra-high magnetic performance of rare-earth nanomagnets via the synergetic combination of calcium-reduction and chemoselective dissolution

Synthesis of mesoscopic particles of multi-component rare earth permanent magnet compounds

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