Synthesis of Nd<sub>2</sub>Fe<sub>14</sub>B powders by spray-drying and reduction–diffusion processes

Dong, Xiyang; Kim, B. K.; Choi, Chul-Jin; Park, K. S.; Zhang, Z. D.

doi:10.1557/jmr.2001.0150

Cited by 11 publications

(3 citation statements)

References 19 publications

(15 reference statements)

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“…Nd 2 Fe 14 B synthesis by reduction−diffusion techniques and their magnetic properties have been reported. − In previous work, a combustion method followed by reduction−diffusion was used to synthesize exchange coupled Nd 2 Fe 14 B−α-Fe nanocomposites in the 5−20 nm size range . However, the mechanism of this process is still not well understood.…”

Section: Introductionmentioning

confidence: 99%

Sol−Gel Based Chemical Synthesis of Nd₂Fe₁₄B Hard Magnetic Nanoparticles

et al. 2010

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Nd2Fe14B hard magnetic nanoparticles were synthesized by chemical synthesis techniques. Nd−Fe−B gel was prepared using NdCl3·6H2O, FeCl3·6H2O, H3BO3, citric acid, and ethylene glycol (EG) by a Pechini type sol−gel method. This gel was subsequently annealed to produce mixed oxide powders. Nd2Fe14B nanoparticles were prepared from these oxides by a reduction−diffusion process. The phase analysis, structure, and magnetic properties were determined by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), and vibrating sample magnetometer (VSM) techniques. The mechanism of Nd2Fe14B formation was investigated by differential scanning calorimetry (DSC), XRD, and thermodynamic free energy change data. Our experimental and modeling results showed that the reduction−diffusion of the Nd−Fe−B mixed oxide was a three step process. The reduction of Fe2O3 to Fe and B2O3 to B occurred at 300 °C. NdH2 and Fe was formed from Nd2O3 and NdFeO3 at 620 °C. The Nd2Fe14B phase was formed from NdH2, Fe, and B at 692 °C. The coercivity of as-synthesized powder was 6.1 kOe. The Henkel plot showed that this powder was exchange coupled; removal of CaO by washing led to dipolar interactions and a decrease in coercivity.

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Section: Introductionmentioning

confidence: 99%

Sol−Gel Based Chemical Synthesis of Nd₂Fe₁₄B Hard Magnetic Nanoparticles

et al. 2010

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“…Hence, the reaction has to be carried out at 900°C for a longer time (say 9h.) [32][33][34]. This may be performed by allowing the precursors to reduce and diffuse among themselves simultaneously to form the respective alloy.…”

Section: La + 5 Ni G Lanimentioning

confidence: 99%

Investigation on the thermodynamic analysis, preparation and characterization of LaNi5 - hydrogen storage alloy by magnesiothermic reduction diffusion process

Giresan

Sankaranarayanan

Berchmans

2016

J min metall B Metall

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The present investigation focuses on the preparation of LaNi 5 intermetallic compound by "Metallothermic reduction diffusion process". Experiments were carried out using oxides and chlorides of La and Ni metal powders as the raw materials with granular Mg powder as the reductant. The thermal reduction process was carried out at 900 ºC for 9 hrs in Ar atmosphere. After the completion of reaction, the contents were purified by treating with dilute acetic acid followed by de-ionized water. Thermodynamic feasibility studies were carried out to determine the probabilistic nature of formation of the desired compound. Thermal analysis was carried out to find the dissociation and decomposition temperature of the reactants. The phase purity and the elemental composition of the alloy were assessed by XRD and EDX analyses. The morphological features of the prepared powders were examined by SEM. From this study, it has been concluded that LaNi5 alloy can be prepared with an appreciable purity by the Metallothermic reduction diffusion process.

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“…Spray drying that has been widely used for preparing granulated ceramic powder provides uniformly dispersed components with exact composition control of a desired compound, yielding fine final products. In fact, we successfully fabricated Nd-Fe-B powder with the particle size < 1 µm by R-D process using spray-dried precursors [6,7]. However, magnetic properties of the powder are not optimized yet.…”

Section: Introductionmentioning

confidence: 99%

Properties of Nd-Fe-B Magnetic Powder Prepared by Reduction-Diffusion Process Using a Spray-Dried Precursor

Jang

Lee

Choi

et al. 2004

MSF

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Effect of washing step in R-D process on the structure and magnetic properties of Nd-Fe-B powder fabricated by the process using a spray-dried precursor was investigated. Although the powder washed in water contained much more residual CaO than that washed in dilute acetic acid, magnetic properties of the former were much better than those of the latter due to less removal of Nd-rich phase. In the powder washed in water Nd2Fe14B particles were enclosed with thin layer of Nd-rich phase, and each particle consisted of one or more subgrains of the size 50 ~ 100 nm or more. Milling the powder before water washing was effective to remove more CaO, thereby increased the remanence of the powder.

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Synthesis of Nd₂Fe₁₄B powders by spray-drying and reduction–diffusion processes

Cited by 11 publications

References 19 publications

Sol−Gel Based Chemical Synthesis of Nd₂Fe₁₄B Hard Magnetic Nanoparticles

Sol−Gel Based Chemical Synthesis of Nd₂Fe₁₄B Hard Magnetic Nanoparticles

Investigation on the thermodynamic analysis, preparation and characterization of LaNi5 - hydrogen storage alloy by magnesiothermic reduction diffusion process

Properties of Nd-Fe-B Magnetic Powder Prepared by Reduction-Diffusion Process Using a Spray-Dried Precursor

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Synthesis of Nd2Fe14B powders by spray-drying and reduction–diffusion processes

Cited by 11 publications

References 19 publications

Sol−Gel Based Chemical Synthesis of Nd2Fe14B Hard Magnetic Nanoparticles

Sol−Gel Based Chemical Synthesis of Nd2Fe14B Hard Magnetic Nanoparticles

Investigation on the thermodynamic analysis, preparation and characterization of LaNi5 - hydrogen storage alloy by magnesiothermic reduction diffusion process

Properties of Nd-Fe-B Magnetic Powder Prepared by Reduction-Diffusion Process Using a Spray-Dried Precursor

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Synthesis of Nd₂Fe₁₄B powders by spray-drying and reduction–diffusion processes

Sol−Gel Based Chemical Synthesis of Nd₂Fe₁₄B Hard Magnetic Nanoparticles

Sol−Gel Based Chemical Synthesis of Nd₂Fe₁₄B Hard Magnetic Nanoparticles