• Resources Recycling
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• v.16 no.2 s.76
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• pp.23-31
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• 2007

In this study, the crystallization of neodymium carbonate from neodymium chloride solution by addition of ammonium bicarbonate was investigated. The concentration of reactants such as neodymium chloride and ammonium bicarbonate, and reaction temperature play an important part in order to obtain the crystal of neodymium carbonate. It seemed that amorphous neodymium carbonate was prepared by aggregation of primary particles formed through nucleation. If reaction rate was increased by increasing the concentration of reactants and reaction temperature, then neodymium carbonate crystal could be obtained. Lanthanite-type neodymium carbonate[$Nd_2(CO_3)_3{\cdot}8H_2O$] and tengerite-type neodymium carbonate[$Nd_2(CO_3)_3{\cdot}2.5H_2O$] could be obtained with reaction renditions. Lanthanite-type neodymium carbonate was sensitive to temperature. The thermal decomposition of neodymium carbonate contained the processes or dehydration, decarbonation and crystalization of $Nd_2O_3$. The shape of lanthanite-type neodymium carbonate was irregular lump type, and tengerite-type neodymium carbonate had the shape of needle type. The shape of $Nd_2O_3$ was affected by the shape of neodymium carbonate.

• Resources Recycling
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• v.13 no.6
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• pp.43-48
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• 2004

For the separation of neodymium from NdFeB permanent magnet scrap, the scrap was roasted for oxidizing, and leached with acetic acid followed by fractional crystallization for selective separation. From the analysis results of the leached solution, the optimum condition for the recovery of neodymium was found that leaching temperature, leaching time and pulp density are 80$^{\circ}C$, 3 hours, and 35%, respectively. At this optimum condition, more than 90% of neodymium could be recovered. Concentration of neodymium acetate in acetic acid. The optimum condition for the recovery of neodymium acetate crystal from the leached solution was that the initial leaching solution was evaporated until the remaining volume was about 1/5 of the initial volume. At this condition, 67.5% of neodymium was recovered from the leached solution. The neodymium remaining in the concentrated solution was recovered by reacting it with oxalic acid.

• Resources Recycling
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• v.12 no.6
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• pp.57-63
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• 2003

In this study, the separation of neodymium was investigated from NdFeB permanent magnet scrap. Decomposition and leach-ing process of NdFeB permanent magnet scrap by oxidation roasting and sulfuric arid leaching were examined. Neodymium could be separated from iron by double salt precipitation using sodium sulfate. The optimum conditions established for decom-position and leaching are as follows: oxidation roasting temperature is $500^{\circ}C$ for sintered scrap and $700^{\circ}C$ for bonded scrap, concentration of sulfuric acid in leaching solution is 2.0 M, leaching temperature and time is $50^{\circ}C$ and 2 hrs, and pulp density is 15%. The leaching yield of neodymium and iron was 99.4% and 95.7% respectively. The optimum condition for separation of neodymium by double-salt precipitation was 2 equivalents of sodium sulfate and $50^{\circ}C$ The yield of neodymium was above 99.9%.

• Journal of the Korean institute of surface engineering
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• v.54 no.2
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• pp.71-76
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• 2021

Ag925, silver with added copper, is popular alloy due to its low price. However, it has a difficult to use because of the low corrosion resistance. In various alloys, neodymium (Nd) works as an element to improve corrosion resistance by reacting with interstitial elements in the alloy. When 1.5 wt. % Neodymium was added to Ag925, the potential on the activated polarization in a potentiodynamic polarization test was increased from -0.15 V to -0.05 V. Ag925 with added neodymium showed the passivation after activation polarization. But When the potential increased around 50 mV, the current density is increased to 3 × 10-3. Ag925 with the 1.5 wt. % Nd had the low corrosion rate.

• Korean Journal of Materials Research
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• v.13 no.4
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• pp.228-232
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• 2003

The effects of$ Nd_2$$O_3$addition on the properties of Mn-Zn ferrite were investigated in the doping concentration range from 0.05 to 0.25 wt%. All samples were prepared by standard fabrication of ferrite ceramics. With increasing the Neodymium oxides, specific density and initial permeability increased on the whole. But, the tendencies such as upper result had the measured value on limitation and characteristics saturated or decreased properties after that. With increasing the content of Neodymium oxides. both the real and imaginary component of complex permeability and the magnetic loss(tan$\delta$) increased. Because reason that magnetic loss increases is high ratio that a real department increases than imaginary department. Magnetic loss increased none the less for increasing the real department related with magnetic permeability. But, the magnetic loss of ferrite doped with the Neodymium oxides were lower than that of none doped Mn-Zn ferrite. The small amount of percent Neodymium oxides in Mn-Zn ferrite composition led to enhancement of resistivity in bulk, and more so in the grain boundary.

• Bulletin of the Korean Chemical Society
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• v.35 no.3
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• pp.886-890
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• 2014

The properties of magnetic material of Nd-Fe-B are highly affected by various factors such as particle size, magnetic anisotropy, phase purity and crystal structure. Incorporation of excess neodymium was carried out in various percentages so that it will adjust the proportion of neodymium in the host crystal after reduction treatment and finally help to improve magnetic property of a material. The interdiffusion of Nd-Fe and boron was studied for various compositions and their effect on magnetic property was understood with theoretical concepts. The factors such as amount of hard and soft phase in the reduction treated product is also responsible for the possible exchange coupling between hard and soft phase magnets for better magnetic properties.

• Journal of Advanced Engineering and Technology
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• v.6 no.2
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• pp.125-129
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• 2013

In the pyrochemcial process of spent nuclear fuel, it is necessary to separate rare earth nuclides from LiCl-KCl eutectic waste salt for radioactive waste reduction. This paper presents the phosphorylation of neodymium chloride in LiCl-KCl-NdCl₃ system using Li₃PO₄-K₃PO₄ as a phosphorylation agent in a chemical reactor with pitched blade impellers. The phosphorylation test was performed changing operation temperature, stirring rate, and amount of phosphorylation agent. Neodymium chloride was effectively converted into neodymium phosphate (NdPO₄). It was confirmed that more than 99 wt% of neodymium can be separated from LiCl-KCl-NdCl₃ system using a phosphorylation method l

• Resources Recycling
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• v.13 no.5
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• pp.37-44
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• 2004

In this study, neodymium oxalate powders were prepared by injecting oxalic acid to the neodymium chloride solution resulted from the acid leaching solution of NdFeB magnet scrap. The effect of experimental conditions on the characteristics of neodymium oxalate powders were investigated. Neodymium oxalate was aggregated by primary particles formed by nucleation, and average size of aggregates was affected by experimental conditions. In a constant volume, increase of reactants affected the average size of aggregate formed by collision of primary particles. In a constant concentration of reactants, agitation speed decreased the size of aggregate due to breakage of particles attached on the surface of aggregate. The number of primary particles decreased with increasing reaction temperature, and the size of aggregates decreased due to the decrease of collision probability. From the results of decomposition behavior of neodymium oxalate, oxalate decomposed from $400^{\circ}C$, and neodymium oxide began to crystallize at above $620^{\circ}C$.

• Applied Chemistry for Engineering
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• v.7 no.5
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• pp.913-924
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• 1996

In this study HDS(hydrodesulfurization) of thiophene was researched over nickel catalysts added with small amounts of neodymium which were prepared by different methods such as unsupported coprepricipitated NdNi catalysts, unsupported intermetallic $NdNi_5$ catalysts, and carbon supported NdNi catalyst. The HDS activity was remarkably increased when a small amounts of neodymium was added to unsupported coprecipitated Ni catalysts. Thus it was known that the role of Nd is important in HDS of thiophene of Ni catalysts. For the case of unsupported intermetallic $NdNi_5$, the intermetallic crystallinity was destroyed to oxide and sulfide after calcination and presulfidation respectively. The HDS activity of thiophene can be explained by surface area of unsupported catalysts. And Nd acts like as structural promoter keeping the high surface area of unsupported catalysts. The HDS activity was increased by each ten times based on 1 gr. of nickel in the order of unsupported intermetallic $NdNi_5$, unsupported coprecipitated NdNi, and carbon supported NdNi catalysts according to different preparation method of catalysts.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.2
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• pp.233-240
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• 2021

For the production of neodymium-doped zinc sulfide thin films in various amounts, zinc sulfide and neodymium were simultaneously deposited using an RF magnetron sputtering equipment to form a thin films, and rapid thermal annealing was performed at 400℃ for 30 minutes as a post-treatment process. The structure, shape, and optical properties of ZnS thin films having various neodymium doping contents (0.35at.%, 1.31at.%, 1.82at.% and 1.90at.%) were studied. The X-ray diffraction pattern was grown to a (111) cubic structure in all thin films. The surface and structural morphology of the thin films due to the neodymium doping content was explained through SEM and AFM images. Only elements of Zn, S, and Nd that do not contain other impurities were identified through EDAX. The transmittance and band gap of the prepared thin films were confirmed using the UV-vis spectrum.