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A Metallurgical Study on Sputtered thin Film Magnet of high $_{i}\textrm{H}_{c}$ Nd-(Fe, Co)-B alloy and Magnetic

  • Kang, Ki-Won;Kim, Jin-Ku;Song, Jin-Tae
    • Korean Journal of Materials Research
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    • v.4 no.5
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    • pp.535-540
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    • 1994
  • Thin film magnet was fabricated by radio frequency magnetron sputtering using $Nd_13/(Fe.Co)_{70}B_{17}$ alloy target and magnetic properties were investigated according to sputtering conditions from the metallurgical point of view. we could obtain the best preferred orientation of $Nd_2Fe_{14}B$ phase at substrate temperatures between $450^{\circ}C$ and $460^{\circ}C$ with the input power 150W, and thin films had the anisotropic magnetic properties. But, as the thickness of thin film increased, the c-axis orientation gradually tended to be disordered and magnetic properties also become isotropic. Just like Nd-Fe-B meltspun ribbon, the microstructure of thin film magnet was consisted of very find cell shaped $Nd_2Fe_{14}B$ phase and the second phase along grain boundary. While, domain structure showed maze patterns whose magnetic easy axis was was perpendicular to film plane of thin film. It was concluded from these results that the perpendicualr anisotropy in magnetization was attributed to the perpendicular alignment of very find $Nd_2Fe_{14}B$ grains in thin film.

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EFFECT OF POWDER SIZE ON THE MICROSTRUCTURE AND MAGNETIC PROPERTIES OF Nd-Fe-B MAGNET ALLOY

  • JU-YOUNG CHO;SARDAR FARHAT ABBAS; YONG-HO-CHOA;TAEK-SOO KIM
    • Archives of Metallurgy and Materials
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    • v.64 no.2
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    • pp.623-626
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    • 2019
  • Rare earth Nd-Fe-B, a widely used magnet composition, was synthesized in a shape of powders using gas atomization, a rapid solidification based process. The microstructure and properties were investigated in accordance with solidification rate and densification. Detailed microstructural characterization was performed by using scanning electron microscope (SEM) and the structural properties were measured by using X-ray diffraction. Iron in the form of α-Fe phase was observed in powder of about 30 ㎛. It was expected that fraction of Nd2Fe14B phase increased rapidly with decrease in powder size, on the other hand that of α-Fe phase was decreased. Nd-rich phase diffused from grain boundary to particle boundary after hot deformation due to capillary action. The coercivity of the alloy decreased with increase in powder size. After hot deformation, Nd2Fe14B phase tend to align to c-axis.

Microwave Dielectric Properties of the $BaO-(Nd,Bi)_2 O_3-TiO_2$$_2$ Ceramic for Mobile Communication Component (이동 통신 부품에 이용되는 $BaO-(Nd,Bi)_2 O_3-TiO_2$계 마이크로파 유전체의 유전 특성)

  • 윤중락;이헌용;김경용;이석원
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.11 no.11
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    • pp.947-953
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    • 1998
  • The microwave dielectric properties of X BaO-0.15($Nd_{0.87}Bi_{0.13})_2O_3-(0.85-X)TiO_2 (X=0.14~0.17) and 0.16BaO-0.15(Bi_xNd_{1-x})_2O_3-0.69TiO_2$ (X=0.12~0.15) ceramics sintered at 1320~$1380^{\circ}C$ were investigated. The microwave dielectric properties of X BaO-0.15(Nd_{0.87}Bi_{0.13})_2O_3-(0.85-X)TiO_2$ (X=0.14~0.17) can be controlled effectively by adjusting X content : with increasing X from 0.14 to 0.17 both dielectric constant and temperature coefficient of resonant frequency decreased from 94.6 to 86 and from 22 ppm/^${\circ}C to -7 ppm/^{\circ}C$, respectively, while quality factor increased from 1300 to 1920 (at 4GHz). The microwave dielectric properties of 0.16BaO-0.15(Bi_x/Nd_{1-x2}O_3 -0.69TiO_2$ (X=0.12~0.15) can be controlled effectively by adjusting X content : with increasing X from 0.12 to 0.15 both quality factor and temperature coefficient of resonant frequency decreased from 1920 to 1430 and from 9 ppm/^${\circ}C to -10 ppm/^{\circ}C$, respectively, while dielectric constant increased from 87.5 to 92.6.

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Phase Evolution Behavior of (Bi,Nd)(Fe,Ti)O3 Ceramics and Thin Films ((Bi,Nd)(Fe,Ti)O3 세라믹스와 박막의 상형성 거동)

  • Kim, Kyung-Man;Lee, Hee-Young
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.23 no.12
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    • pp.949-955
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    • 2010
  • Nd and Ti co-doped bismuth ferrite $(Bi_{1-x}Nd_x)(Fe_{1-y}Ti_y)O_3$ (x, y = 0, 0.05, 0.1, 0.2) ceramics and thin films were synthesized through the conventional mixed-oxide process and pulsed laser deposition (PLD), respectively. Nd and Ti co-doping effect was examined with emphasis on how these impurities affect phase formation behavior as there could be the improvement in leakage current problems often associated with multiferroic $BiFeO_3$ (BFO) thin films. The lattice constants of BFO ceramics decreased with Nd doping concentration up to 10mol%, while they further decreased with Nd and Ti co-doping to about 20%. BFO thin films obtained by the PLD process revealed random polycrystalline structure. Similar to bulk BFO ceramic, Nd and Ti co-doping effectively suppressed the formation of unwanted secondary phase and thus stabilized the perovskite phase in BFO thin films.

Enhanced Superconducting Properties in Melt-processed (Y0.33Sm0.33Nd0.33) Ba2Cu3Oy Oxides in Air

  • Kim, So-Jung;Park, Jong-Kuk
    • Transactions on Electrical and Electronic Materials
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    • v.6 no.6
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    • pp.284-288
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    • 2005
  • We have systematically studied the superconducting properties and flux pinning enhancement of $(Y_{0.33}Sm_{0.33}Nd_{0.33})\;Ba_2Cu_3O_y$ [(YSN)-123] composite oxides by melt growth process in air. A sample prepared by this method showed well-textured microstructure, and $(Y_{0.33}Sm_{0.33}Nd_{0.33})\;BaCuO_5$ [(YSN)211] nonsuperconducting particles were uniformly dispersed in large (YSN) 123 superconducting matrix. The sample showed a sharp superconducting transition at 91 K. The magnetization measurements of the (YSN)-123 sample exhibited the enhanced flux pinning, compared with $YBa_2Cu_3O_y$ (Y-123) sample without Sm and Nd. Critical current densities of (YSN)-123 sample was $2.5{\times}10^4 A/cm^2$ at 2 T and 77 K.

Crystal growth and pinning enhancement of directionally melt-textured$(Y_{0.5}Nd_{0.25}Sm_{0.25})Ba_2Cu_3O_y$ oxides in air

  • Kim So-Jung
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.15 no.5
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    • pp.188-192
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    • 2005
  • High $T_c(Y_{0.5}Nd_{0.25}Sm_{0.25})Ba_2Cu_3O_y[(YNS)-123]$ superconductors with/without $CeO_2$ additive were systematically investigated by the zone melt growth process in air. Cylindrical green rods of (YNS)-123 oxides were fabricated by cold isostatic pressing (CIP) method using rubber mould. A sample prepared by this method showed well-textured microstructure, and $(Y_{0.5}Nd_{0.25}Sm_{0.25})_2BaCuO_5[(YNS)211]$ nonsuperconducting inclusions were uniformly dispersed in large $(Y_{0.5}Nd_{0.25}Sm_{0.25})Ba_2Cu_3O_y$[(YNS)123] superconducting matrix. In this study, optimum melting temperature and growth rate were $1100^{\circ}C$ and 3 mm/hr, respectively. The directionally melt-textured (YNS)-123 sample with $CeO_2$ additive showed an onset critical temperature $(T_c)\;T_c{\geq}93K$ and sharp superconducting transition.

Fabrication of $Nd_{2}Fe_{14}B$ Powders by Spray-Drying and Reduction-Diffusion Processes

  • Park, C. J.;Kim, B. K.;X. L. Dong
    • Proceedings of the Korean Magnestics Society Conference
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    • 2000.09a
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    • pp.393-394
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    • 2000
  • The magnetic alloy of $Nd_{2}Fe_{14}B$-type was synthesized by a mechano-chemical method, including the processes of spray-drying, de-binding, milling, $H_{2}$- and Ca-reduction and washing. The very fine $Nd_{2}Fe_{14}B$ particles smaller than $1\mu\textrm{m}$ could be achieved without the inevitable pulverization step in conventional processes.

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Sintering and Dielectric Properties of $BaO-Nd_2O_3-TiO_2$ Microwave Ceramics for LTCC RE module (LTCC RF 모듈용 $BaO-Nd_2O_3-TiO_2$계 세라믹스의 저온소결 및 마이크로파 유전특성)

  • Shin, Dong-Soon;Choi, Young-Jin;Park, Jae-Hwan;Nahm, Sahn;Park, Jae-Gwan
    • Journal of the Microelectronics and Packaging Society
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    • v.10 no.1
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    • pp.57-63
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    • 2003
  • The effects of glass addition on the low-temperature sintering and microwave dielectric properties of $BaO-Nd_2O_3-TiO_2$ dielectric ceramics were studied. When 10∼13 wt% of lithium borosilicate glass was added, the sintering temperature decreased from 130$0^{\circ}C$to 850-$900^{\circ}C$relative density of more than 97% was obtained. When the sample was sintered at $850^{\circ}C$ with 10 wt% of glass, the dielectric properties of $\epsilon_r{\ge}54$, $Q{\times}f_0{\ge}2300$, and $\tau_f{\ge}+8ppm/^{\circ}C$ were obtained.

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A study on formation of hemoglobin adduct due to inhalation exposure with 1,3-butadiene in female mice

  • Lee, Jin-Heon;Shin, Ho-Sang
    • Proceedings of the Korean Environmental Health Society Conference
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    • 2004.06a
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    • pp.73-86
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    • 2004
  • The purpose of this study is the identification of (N-2-hydroxy-3-butenyl) valine(HBVal adduct) and (N-2,3,4-trihydroxy-butyl)valine(THBVal adduct)with mice inhalation exposure with 1,3-butadiene for 3 weeks($6\;hr/day\;{\times}\;5\;days/week$). Body weights were significantly lower from 4 or 9 exposure post-day in 1000 or 500ppm inhalation group than in control. The levels of HBVal adducts are 1.8, 3.7 and 6.2 pmol/mg globin in $1^{st}$, $2^{nd}$ , and $3^{rd}$ week for 500 ppm 1,3-butadiene(BD), and 5.7, 7.4 and 16.0 pmol/mg globin in $1^{st}$, $2^{nd}$ , and $3^{rd}$ week for 1000 ppm BD inhalation exposure. The levels of THBVal adducts are 32.0, 42.0 and 55.0 pmol/mg globin in $1^{st}$, $2^{nd}$ , and $3^{rd}$ week for 500 ppm BD, and 67.8, 72.7 and 83.5 pmol/mg globin in $1^{st}$, $2^{nd}$ , and $3^{rd}$ week for 1000 ppm BD inhalation exposure. Their ratios of THBVal and HBVal adducts are higher at earlier exposure and lower concentration. They are17.8, 11.4 and 8.87 in $1^{st}$, $2^{nd}$ , and $3^{rd}$ week for 500 ppm BD, and 11.9, 9.8 and 5.2 in $1^{st}$, $2^{nd}$ , and $3^{rd}$ week for 1000 ppm BD inhalation exposure. In conclusion, THBVal and HBVal adducts are a important hemoglobin adduct for monitoring of BD exposure, and the latter is more biomarker than the other.

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Analysis of Harmonic Wave Generation in Nonlinear Oblique Crack Surface (비선형 경사 균열면에서의 고조파 발생 특성 해석)

  • Kim, Noh-Yu;Yang, Seung-Yong
    • Journal of the Korean Society for Nondestructive Testing
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    • v.32 no.4
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    • pp.376-387
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    • 2012
  • Based on the nonlinear spring model coupled with perturbation method, 2nd harmonic waves generated by oblique incident ultrasound on nonlinear crack interface were calculated and investigated. Reflected and transmitted waves from the interface were determined and analyzed at various angle of incidence for the cracks with different interfacial stiffness in order to estimate the 2nd harmonic generation of incident ultrasound. It was shown in computer simulation that the 2nd harmonic components changed much with the increase of incidence angle in both reflected and transmitted wave, but became very small when the incident angle approached toward 90 degree. It can be concluded that the 2nd harmonic component of reflected wave has a meaningful amplitude as much as the transmitted 2nd harmonic wave from partly closed crack.