• Journal of Powder Materials
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• v.26 no.6
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• pp.477-480
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• 2019

Magnetic 0-D Nd₂Fe₁₄B powders are successfully fabricated using 1-D Nd₂Fe₁₄B nanowire formed by an efficient and facile electrospinning process approach. The synthesized Nd-Fe-B fibers and powders are investigated for their microstructural, crystallographic, and magnetic properties according to a series of subsequent heat treatments. Each heat-treatment process leads to the removal of organic impurities and the formation of the respective oxides/composites of Nd, Fe, and B, resulting in the formation of Nd₂Fe₁₄B powders. Nd-Fe-B fibers exhibit the following magnetic properties: The coercivity (H_ci) of 3260 Oe, a maximum magnetization at 3T of 109.44 emu/g, and a magnetization remanence (M_r) of 44.11 emu/g. This process easily mass produces hard magnetic Nd₂Fe₁₄B powders using a 1-D synthesis process and can be extended to the experimental design of other magnetic materials.

• Journal of Powder Materials
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• v.17 no.1
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• pp.1-6
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• 2010

In this study, a convergent heat treatment was performed in certain temperature regions in order to control the microstructures of Nd-rich phases and to reduce thermal stress on grain boundaries which could be caused during expansion and shrinkage of Nd-rich and $Nd_2Fe_{14}B$ phases. The difference of thermal expansion coefficient between $Nd_2Fe_{14}B$ and Nd-rich phases is the mechanism for convergent heat treatment. The Nd-rich phases which were located in junctions could penetrate into the grain boundaries between $Nd_2Fe_{14}B$ phases due to the difference of thermal expansion coefficient. Through the convergent heat treatment, the microcracks that were observed in cyclic heat treatment were not observed and coercivity was increased to 34.05 kOe at 8 cycles.

• The Journal of the Petrological Society of Korea
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• v.20 no.4
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• pp.207-217
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• 2011

Here we report major element composition, trace and rare earth element abundance, Sm-Nd and Rb-Sr isotopic composition from Deokgu leucogranite. Chondrite-normalized REE pattern and its Eu anomaly are divided into 3 types systematically, and have close relationship with $SiO_2$ contents. Such geochemical characteristic indicates that the leucogranite was derived by feldspar fractionation from a common source magma. Sm-Nd and Rb-Sr whole rock ages are $1,785{\pm}180Ma$ (initial $^{143}Nd/^{144}Nd\;ratio=0.51003{\pm}0.00016,\;2{\sigma}$; ${\varepsilon}_{Nd}(T)=-5.9$) and $1,735{\pm}260Ma$ (initial $^{87}Sr/^{86}Sr\;ratio=0.702{\pm}0.046,\;2{\sigma}$), respectively. Initial ${\varepsilon}_{Nd}$ value indicates that the magma should be derived from the crustal material. This initial ${\varepsilon}_{Nd}$ value also corresponds well with those from the Precambrian granitoids from North-China Craton rather than those of South-China Craton.

• Journal of the Korean Magnetics Society
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• v.9 no.3
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• pp.154-158
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• 1999

Magnetic properties and microstructure of nanocrystalline $\alpha$-(Fe, Co)-based Nd-(Fe, Co)-B-Nb-Cu alloys have been investigated. $Nd_x(Fe_{0.9}Co_{0.1})_{90-x}B_6Nb_3Cu_1$(x=2, 3, 4, 5, 6) alloys prepared by rapid solidification process show amorphous phase except the one with x=2. By a proper annealing, the amorphous in the alloy is changed to a nanocrystalline phase. It is confirmed that the nanocrystalline alloys are composed of $\alpha$-(Fe, Co) and $Nd_2(Fe, Co)_{14}B_1$ phase. The optimally annealed $Nd_3(Fe_{0.9}Co_{0.1})_87B_6Nb_3Cu_1$ alloy shows the highest remanence of 1.55 T. The coercivity increases with the increase of Nd content The maximum coercivity of 4.6 kOe is obtained from an optimally annealed $Nd_6(Fe_{0.9}Co_{0.1})_84B_6Nb_3Cu_1$ alloy, resulting in the maximum energy product of 10.6 MGOe.

• Economic and Environmental Geology
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• v.30 no.2
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• pp.153-161
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• 1997

Diagrams of $^{87}Sr/^{86}Sr$ versus Ba/Nb and MgO/FeO are scattered, and $^{87}Sr/^{86}Sr$ variation with the increase of $SiO_2$ are scattered in Gwangju granitoid. Diagrams of $(^{87}Sr/^{86}Sr)$i versus $(^{143}Nd/^{144}Nd)$i and ${\varepsilon}Nd$ versus 1/Nd variation are also scattered in Gwangju granitoid. It shows that the source magma of Gwangju granitoid are derived from partial melting materials of heterogeneous upper crust. Very low ${\varepsilon}Nd$ values (-15.19~-19.49) and very high ${\varepsilon}Sr$ values (92.72~308.85) mean that the source magma of Gwangju granitoid is derived from sedimentary substance melting. According to $(^{87}Sr/^{86}Sr)$ 180Ma, and the plot of ${\varepsilon}Sr$ versus ${\varepsilon}Nd$, the Gwangju granitoid shows that the source magma is derived from upper crust materials. Nd model ages of Gwangju granitoid (1.82~2.42G.A.) are older than meta-sediments of Okcheon formation (1.15~1.60G.A.) and similar or close to Pre-Cambrian gneiss complex of Ryoungnam massif (2.17~2.47G.A.or 2.11~2.38G.A.).Therefore, the source magma of the Gwangju granitoid could be derived from the partial melting of Pre-Cambrian gneiss complex of Ryoungnam massif.

• Journal of Magnetics
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• v.15 no.1
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• pp.32-35
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• 2010

The effects of Cu-addition and die-upset temperature on the texture in the die-upset Nd-lean $Nd_xFe_{93.5-(x+y)}-Cu_yGa_{0.5}B_6$ (x = 9-12, y = 0-2) alloys were investigated. The die-upset Cu-containing Nd-lean $Nd_{12}Fe_{81.5-y}-Cu_yGa_{0.5}B_6$ (y = 1, 2) alloys showed a considerable texture. Texture in the Nd-lean alloys developed through basal plane slip deformation. The Cu-addition reduced the melting point of grain boundary phase facilitating grain gliding during the die-upsetting, and providing a greater chance for the $Nd_2Fe_{14}B$ grains to meet the deformation conditions. Die-upsetting at higher temperature facilitated grain gliding and plastic deformation, thus enhancing texture.

• Journal of Oral Medicine and Pain
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• v.30 no.4
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• pp.447-455
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• 2005

The purpose of this study was to examine the effect of Nd:YAG laser irradiation for sensory nerve conduction change. Nd:YAG laser was irradiated to mental region for 5 minutes with the parameters that 10 Hz and 20 Hz of 100 mJ/pulse. Target size of irradiation was 30 mm diameter of circle and target-tip distance was about 10 mm. Therefore, the power density were 212 $mW/cm^2$ and 424 $mW/cm^2$. Sensory nerve conduction was evaluated with $Neurometer^{\circled}$ CPT/C before and after Nd:YAG laser irradiation. As an outcomes, the current perception threshold(CPT) and pain tolerance threshold(PTT) were obtained. We made a comparison of these two values and the results were as follows. 1. There was no significant difference in CPT at 1W, 10 Hz and 2 W, 20 Hz Nd:YAG laser irradiation. 2. There was no significant difference in PTT at 10 Hz, 20 Hz of 100 mJ/pulse Nd:YAG laser. 3. There were no significant differences in CPT and PTT between 1 W, 10 Hz group and 2 W, 20 Hz group. Therefore, We can make a conclusion that Nd:YAG laser irradiation to mental region have no effect on mental nerve conduction in our study model.

• Proceedings of the Korean Magnestics Society Conference
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• 2002.12a
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• pp.240-241
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• 2002

Tetragonal 구조를 갖는 정량적 Nd$_2$/Fe$_{14}$B (~Nd$_{12}$Fe$_{82}$B$_{6}$) 화합물에서의 Nd 양보다 적은 양의 Nd를 함유하는 Nd-Fe-B 합금에서는, 일반적으로 입자크기가 큰 연자성 $\alpha$-Fe가 과다하게 존재하면서 외부에서 가해주는 자장에 대해 강자성 Nd$_2$/Fe$_{14}$B와 별개의 자기적 거동을 보여주기 때문에, 보자력이 아주 적어 실용성이 없다. 그러나 이러한 합금을 급랭응고하여 미세 결정화하거나, 비정질화한 후 적절히 열처리 해주면 a-Fe와 Nd$_2$/Fe$_{14}$B 입자가 나노화하면서 이들 사이에 상호교환작용이 일어나 등방성 상태에서도 M$_{s}$ /2 보다 큰 잔류자화와 함께 적절한 크기의 보자력도 얻을 수 있다. (중략중략

• Korean Journal of Materials Research
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• v.9 no.1
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• pp.3-7
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• 1999

The change of phosphorescent property with chemical modification and co-doping of Nd as an auxiliary activator in CaAl$_2$$O_4$: Eu\ulcorner, Nd\ulcorner phosphor, employing Nd\ulcornerion(0.6%) and an co-activator maintained its afterglow for 4.5 hours. And also the initial persistent brightness and phosphorescent property were further improved both by substituting Al by B atoms and incorporation of Nd\ulcorner ion. It was found that the persistent time was 30 hours for&Ca(Al_{0.97}\;B_{0.03}) $_2$$O_4$:EU\ulcorner(0.3%), Nd\ulcorner(0.6%) phosphor.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.12 no.1
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• pp.50-55
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• 2002

$Nd_2O_3$0.2~0.5 wt.% doped $LiNbO_3$single crystals were grown by the Czochralski method. The ZnO doping by 2~8 mole% can improve the resistance of optical damage. In this study, Nd : LiNbO$_3$ single crystals with the periodical domain structure were obtained by CZ method.