• 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.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05a
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• pp.6-8
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• 2004

The NdBaCuO superconductor samples were zone-melted in low oxygen partial pressure (1 % $O_2$＋99%Ar). The zone-melting temperature was decreased about 12$0^{\circ}C$ from 1, 06$0^{\circ}C$, the zone-melting temperature in air. Thus the loss of liquid phase (BaCu $O_2$and CuO) was reduced during the zone-melting process. The content of non-superconducting phase Nd422 in zone-melted NdBaCuO samples was clearly decreased and, therefore, the substitution of Nd for Ba was occurred. The superconductivity of zone-melted N $d_{1＋x}$B $a_{2－x}$C $u_3$ $O_{y}$prepared under low oxygen partial pressure was distinctively improved.d.d.d.

• Journal of the Korean Ceramic Society
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• v.41 no.6
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• pp.444-449
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• 2004

The microwave dielectric properties of low temperature sintered BaO-Nd$_2$O$_3$-TiO$_2$ (here after BNT) with a Pb-based glass-ceramics were studied in order to investigate their applicability to Low Temperature Co-fired Ceramics (LTCC) for fabrication of multilayered Radio Frequency (RF) passive components module. The BNT ceramics, with 5∼30 wt% of PbO-TiO$_2$-A1$_2$O$_3$-SiO$_2$ based glass-ceramics, were sintered at 105$0^{\circ}C$, which is lower than 130$0^{\circ}C$, sintering temperature of pure BNT ceramics. With increasing the amount of the glass-ceramics, sintering rate of the ceramics become activated due to the softening of glass, resulting in low-temperature densification. BaO-Nd$_2$O$_3$-TiO$_2$ microwave ceramics with 20 wt% glass-ceramics exhibit sintered relative densities over 95% and dielectric constant of 72, quality factor of 1500, and temperature coefficient of frequency of +22 ppm/$^{\circ}C$. This enhanced dielectric properties are attributed to mainly the presence of crystalline phases PbTiO$_3$ within the Pb-based glass.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.2
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• pp.301-308
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• 1997

The LNT ceramics which has the large negative temperature coefficient of resonant frequency ($\tau_1$) were manufactured by varying the $TiO_2$ contents. The effects of secondary phase $TiO_2$ which was caused by excess $TiO_2$ on the microstructure, phase transformations and microwave dielectric properties in ($Li_{1/2}Nd_{1/2}$)$TiO_3$ binary system were studied by X-ray and SEM. In case of adding up to 5 mol% $TiO_2$ on LNT, the liquid phase $TiO_2$which was created in the grain boundary of LNT not only increased the bulk density but also caused the nonhomogeneous structure of LNT which reduced the microwave dielectric characteristics. But the temperature coefficient of resonant frequency was improved by the 10 mol% addition of $TiO_2$.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2005.09a
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• pp.68-72
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• 2005

본 논문에서는 $Bi_{3}Ti_{4}O_{12}$에 Nd를 치환했을 때 향상되는 강유전체 특성을 sol-gel 방법을 이용하여 분석하였다. 이를 위해 $10\;wt\%$의 $12\%$과량의 Bi가 첨가된 $Bi_{3.15}Nd_{0.85}Ti_{13}O_{12}$ sol-gel 용액을 제작하였다. BNT 박막은 $Pt/TiO_2/SiO_2/Si$ 기판 위에 스핀 코팅 방법을 이용하여 증착하였으며, 최종 증착된 박막의 조성은 Rutherford backscattering spectroscopy 분석을 이용하여 $Bi_{3.15}Nd_{0.85}Ti_{13}O_{12}$임을 확인하였다. 200 nm 두께의 BNT 박막은 XRD 분석을 통해 (117)방향에서 강한 피크가 나오며, (001) 방향에서 Nd 치환에 따른 효과로 억제된 피크가 나오는 것을 확인하였다. Pt/BNT/Pt 구조를 이용하여 잔류분극을 측정한 결과 7 V에서 $48\;{\mu}\;C/cm^2$ 이 나왔다. 이것은 다른 강유전체 물질인 PZT, SBT, BLT보다 월등히 큰 값이다.

• Journal of Korean Society on Water Environment
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• v.28 no.3
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• pp.401-408
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• 2012

High-voltage dielectric discharges are an emerging technique in environmental pollutant degradation, which that are characterized by the production of hydroxyl radicals as the primary degradation species. The initiation and propagation of the electrical discharges depends on several physical, chemical, and electrical parameters such as 1st and 2nd voltage of power, gas supply, conductivity and pH. These parameters also influence the physical and chemical characteristics of the discharges, including the production of reactive species such as OH, $H_2O_2$ and $O_3$. The experimental results showed that the optimum 1st voltage and air flow rate for RNO (N-Dimethyl-4-nitrosoaniline, indicator of the generation of OH radical) degradation were 160 V (2nd voltage of is 15 kV) and 4 L/min, respectively. As the increased of the 2nd voltage (4 kV to 15 kV), RNO degradation, $H_2O_2$ and $O_3$ generation were increased. The conductivity of the solution was not influencing the RNO degradation and $H_2O_2$ and $O_3$ generation. The effects pH was not high on RNO degradation. However, the lower pH and the conductivity, the higher $H_2O_2$ and $O_3$ generation were observed.

• Journal of the Korean Magnetics Society
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• v.15 no.2
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• pp.118-124
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• 2005

We have obtained sharp and clearly resolved ESR spectra of $Nd^{3+}$ and $Er^{3+}$ in vapor transport equilibrium (VTE) treated $LiNbO_3$ crystals, consequently have determined more accurate spin Hamiltonian parameters, than those in congruent samples. The anisotropic hyperfine structures of $^{143}Nd^{3+}$ and $^{145}Nd^{3+}$ in the VTE-treated crystals at liquid helium temperature have been analyzed. It is proposed that both rare earth ions favor the lithium site in $LiNbO_3$ from the consideration of the determined anisotropic g-values.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.19 no.3
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• pp.353-366
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• 2021

The solubilities of different multicomponent lanthanide oxide (Ln₂O₃) solid solutions including binary (Ln₁ and Ln₂ = La, Nd, Eu, or Tm), ternary (Ln₁, Ln₂, and Ln₃ = La, Nd, Eu, or Tm), and higher systems (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) were studied after aging for four weeks at 60℃. Our recent study revealed that the phase transformations in binary ((La, Nd) and (La, Eu)) and ternary (La, Nd, Eu) systems are responsible for the formation of (La, Nd)(OH)₃, (La, Eu)(OH)₃, and (La, Nd, Eu)(OH)₃ solid solutions, respectively. The variations in the mole fractions of La³⁺, Nd³⁺, and Eu³⁺ in the sample solutions of these hydroxide solid solutions indicated that a thermodynamic equilibrium might account for the apparent La, Nd, and Eu solubilities. Conversely, the binary and ternary systems containing Tm₂O₃ as the heavy lanthanide oxide retained the oxide-based solid solutions, and their solubility behaviors were dominated by their congruent dissolutions. In the higher multicomponent system, the X-ray diffraction patterns of the solid phases, before and after contact with the aqueous phase indicated the formation of a stable oxide solid solution and their solubility behavior was explained by its congruent dissolution.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.3
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• pp.231-237
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• 2003

RE(Nd, Sm) elements doped (RE/Y)$_{1.8}$B $a_{2.4}$C $u_{3.4}$$O_{7-x}$ [(RE/Y)1.8] high $T_{c}$ superconductors were directionally grown by Top Seed Melt Growth(TSMG) process in air atmosphere. The (001)melt-textured N $d_{1.8}$B $a_{2.4}$C $u_{3.4}$ $O_{7-X}$(Nd1.8) seed crystals were used for achieving the c-axis alignment large grains perpendicular to surface of the samples. The (RE/Y)1.8 SEM micrographs of the melt-textured (RE/Y)1.8 samples revealed that the nonsuperconducting (RE/Y)211 inclusions are uniformly distributed in the superconducting (RE/Y)123 matrix except the region very close to the Nd seed crystal. The microstructure and superconducting properties were investigated by XRD, SEM, TEM and SQUID magnetometer. The Melt-textured (RE/Y)1.8 samples showed an onset $T_{c}$=91K and sharp superconducting transition. Also, the magnetization value of the (RE/Y)1.8 samples were compared with those of Y1.8 sample at 77 K. 77 K. 77 K. 77 K.K.

• Korean Journal of Environmental Agriculture
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• v.15 no.3
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• pp.282-288
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• 1996

Because of the high water content of the household garbage, it is difficult to compost it. Therefore, this study was conducted to investigate the possibility of using coal fly ash as humidity conditioner for the household garbage composting. The summarized results are as follows : 1. The maximum temperatures were $35^{\circ}C$ in spring, $47^{\circ}C$ in summer, and $43^{\circ}C$ in winter during the composting periods. 2. The mass was reduced to 70.5% after 60 days. The average volume reduced down to 74.7% after 60 days. 3. The seasonal variation of pH values showed a similar tendency and reached 8.5 after 60 days. 4. The water content was reduced at an early stage of composting and not much changed thereafter. It had 49.7% in spring, 33.9% in summer, and 56.5% in winter after 60 days. Ash contents were not much changed during the composting periods. 5. The contents of inorganic compounds were in the range of $0.06{\sim}4.03%$ $P_2O_5$, $0.01{\sim}2.87%$ CaO, $0.18{\sim}1.43%$ MgO, and $0.39{\sim}2.03%$ $K_2O$. Heavy metal contents were in the range of $ND{\sim}14.08$ Hg ${\mu}g/kg$, $ND{\sim}0.80$ Cd mg/kg, $4.99{\sim}28.95$ Cu mg/kg, $ND{\sim}242.62$ Cr mg/kg, $ND{\sim}20.24$ Pb mg/kg, and $ND{\sim}59.87$ Zn mg/kg.