• 제목/요약/키워드: $SrI_2$

검색결과 393건 처리시간 0.025초

육방정 스트론튬 페라이트의 자기적 특성에 미치는 입도 분포의 영향 (Effect of particle size distribution on the magnetidc properties of hexagonal strontium ferrite)

  • 송창열;신용덕
    • E2M - 전기 전자와 첨단 소재
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    • 제8권3호
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    • pp.324-331
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    • 1995
  • 0.36[wt%l $SiO_{2}$ and 0.1[wt%] $H_{3}$B $O_{3}$ were added to strontium ferrite magnets of the magnetoplumbite phase SrO.5.7F $e_{2}$ $O_{3}$ to hinder grain growth and accelerate sintering, respectively. This experiment was carried out to investigate effect of particle size distribution as a function of milling time(20, 30, 40, 50, 60, 70 hours) on the magnetic properties of SrO.5.7F $e_{2}$ $O_{3}$ ferrite magnet. The B-H curve, density and the degree of orientation were measured. And the microstructure of ferrite magnets was examined with a SEM. The optimal conditions and properties of the typical sample are the following : The milling time was 60 hours. Magnetic and physical properties are $B_{r}$=4, 000[G], $_{b}$ $H_{c}$=3, 330[Oe], (BH)max=3.786[MGOe], $_{I}$ $H_{c}$=3, 525[Oe], density=5.0063[g/c $m^{3}$] and orientation factor f=0.813.0.813.3.3.

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YBa$_2$Cu$_3$O$_{7-{\delta}}$/SrTiO$_3$/YBa$_2$Cu$_3$O$_{7-{\delta}}$ multilayer structures for ground planes for ramp-edge junction devices

  • Kim, C.H.;Kim, Y.H.;Jung, K.R.;Hahn, T.S.;Park, J.H.;Choi, S.S.
    • 한국초전도학회:학술대회논문집
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    • 한국초전도학회 2000년도 High Temperature Superconductivity Vol.X
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    • pp.179-183
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    • 2000
  • For a ground plane in high-temperature superconducting ramp-edge junction devices, YBa$_2$Cu$_3$O$_{7-{\delta}}$/SrTiO$_3$/YBa$_2$Cu$_3$O$_{7-{\delta}}$ multilayer structures were fabricated using pulsed laser deposition and ECR ion milling. Various process parameters were adjusted to enhance the device characteristics. By etching the STO layer to form a tapered edge of about 15$^{\circ}$ and in-situ RF plasma treatment of bottom YBCO surface prior to deposition of top YBCO, the top-to-bottom YBCO showed T$_c$ of 75${\sim}$80 K and I$_c$ of about 40 mA through holes. It was found that the deposition of bottom YBCO at a reduced laser repetition rate of 1Hz increased the T$_c$ of top YBCO to 79.9 K. The resistivity of 570 layer was about 10$^6$ ${\Omega}$cm at 60 K, which ensures good electrical isolation between successive YBCO layers.

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담양(潭陽)-진안(鎭安)사이에 분포(分布)하는 엽리상화강암류(葉理狀花崗岩類)에 대(對)한 지질시대(地質時代)와 성인(成因)에 관(關)한 연구(硏究) (Geochronology and Petrochemistry of Foliated Granites between Damyang and Jinan)

  • 김정빈;김용준
    • 자원환경지질
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    • 제23권2호
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    • pp.233-244
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    • 1990
  • Plutons of Damyang-Jinan area consist of gray feldspar granite gneiss, biotite granite gneiss, foliated granites, Namweon granites, gabbro, biotite granite and Ogangri granite in term of mineralogical, texture and field evidence. From Isotope data of study area, chronological order of the Plutons are the Pre-cambrian gray feldspar granite gneiss(Ar39-Ar40, hornblende, $1998.4{\pm}8.3Ma$), middle to late Triassic Daegang foliated granite(Rb/Sr, whole rock, $288{\pm}4Ma$), foliated hornblende biotite granodiorite(K/Ar, hornblende, $198.7{\pm}9.9Ma$), Sunchang foliated granodiorite(Rb/Sr, whole rock, $222{\pm}4Ma$), foliated two mica granite, Samori foliated granite and Namweon granite(Rb/Sr, whole rock, $211{\pm}3Ma$: K/Ar, hornblende, $203{\pm}10.2Ma$), middle Jurassic Gabbro(K/Ar, hornblende, $180.7{\pm}9MA$) and biotite granite, and Cretaceous Ogangri granite. According to variations diagrams of $Al_2O_3$ versus normative PI(100 An)/(Ab+An), Daegang foliated granite is plotted on tholeiitic series, and other foliated granites on calc alkaline rock series which are consider to be formed by magmatism at continental margin and island arc region. And alkalinity versus $SiO_2$ shows that Daegang folited granite and Samori foliated granite are correspond to alkaline region, foliated hornblende biotite granodiorite and Sunchang foliated granodiorite to calc alkaline region, and foliated two mica granite to both regions. According to ACF diagrams, Daegang and Samori foliated granites are plotted on S-type. Foliated hornblende biotite granodiorite and Sunchang foliated granodiorite on I-type, and foliated two mica granite on both type. Foliated granites are a series of differentiated products from cogenetic magma, and effected under ductile sheared zone. Characteristic foliation of foliated granites are considered to be generated by dextral strike slip faulting and ductile shearing.

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Magnetic Properties and Magnetocaloric Effect in Ordered Double Perovskites Sr1.8Pr0.2FeMo1-xWxO6

  • Hussain, Imad;Anwar, Mohammad Shafique;Khan, Saima Naz;Lee, Chan Gyu;Koo, Bon Heun
    • 한국재료학회지
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    • 제28권8호
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    • pp.445-451
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    • 2018
  • We report the structural, magnetic and magnetocaloric properties of $Sr_{1.8}Pr_{0.2}FeMo_{1-x}W_xO_6$($0.0{\leq}x{\leq}0.4$) samples prepared by the conventional solid state reaction method. The X-ray diffraction analysis confirms the formation of the tetragonal double perovskite structure with a I4/mmm space group in all the synthesized samples. The temperature dependent magnetization measurements reveal that all the samples go through a ferromagnetic to paramagnetic phase transition with an increasing temperature. The Arrott plot obtained for each synthesized sample demonstrates the second order nature of the magnetic phase transition. A magnetic entropy change is obtained from the magnetic isotherms. The values of maximum magnetic entropy change and relative cooling power at an applied field of 2.5 T are found to be $0.40Jkg^{-1}K^{-1}$ and $69Jkg^{-1}$ respectively for the $Sr_{1.8}Pr_{0.2}FeMoO_6$ sample. The tunability of magnetization and excellent magnetocaloric features at low applied magnetic field make these materials attractive for use in magnetic refrigeration technology.

상부전극에 따른 $(Sr_{0.85}Ca_{0.15})TiO_3$ 박막의 전기적 특성 (Electrical Properties of $(Sr_{0.85}Ca_{0.15})TiO_3$ Thin Films with Top Electrodes)

  • 조춘남;김진사;신철기;오재한;최운식;김충혁;이준웅
    • 대한전기학회논문지:전기물성ㆍ응용부문C
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    • 제49권2호
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    • pp.107-112
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    • 2000
  • $(Sr_{0.85}Ca_{0.15})TiO_3$(SCT) thin films were deposited on Pt-coated $TiO_2/SiO_2/Si$ wafer by the rf sputtering method. Experiments were conducted to investigate the electrical properties of SCT thin films with various top electrodes. Various top electrodes as Pt, Al, Ag, Cu were deposited on SCT thin films by sputter and thermal evaporator. The characteristics of C-F and C-V of SCT thin films were not obviously varied with various top electrodes, SCT thin films annealed at $600^{\circ}C$ represents as favorable capacitance characteristics than SCT thin films not annealed, and Pt top electrode have the most high capacitance. The characteristic of I-V of SCT thin films showed that Pt top electrode revealed more less leakage current density than other electrodes, had a leakage current density below 10-8$[A/cm^2]$ until 25[V] applied voltage.

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Influence of Yb2O3 Doping Amount on Screen-printed Barium Strontium Calcium Titanate Thick Films

  • Noh, Hyun-Ji;Lee, Sung-Gap;Ahn, Byeong-Lib;Lee, Ju
    • Transactions on Electrical and Electronic Materials
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    • 제8권6호
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    • pp.241-245
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    • 2007
  • [ $(Ba_{0.9-x}Sr_xCa_{0.10})TiO_3$ ] (x=0.33, 0.36) powders were prepared by sol-gel method. $(Ba,Sr,Ca)TiO_3$(BSCT) thick films, undoped and doped with $MnCO_3$ and $Yb_2O_3(0.1{\sim}0.7mol%)$, were fabricated by the screen printing method on the alumina substrate. The coating and drying procedure was repeated 6-times. The Pt bottom electrode was screen printing method on the alumina substrate. These BSCT thick films were annealed at $1420^{\circ}C$ for 2 hr in atmosphere. The upper electrodes were fabricated by screen printing the Ag paste and then firing at $590^{\circ}C$ for 10 min. And then the structured and dielectric properties as a function of the doping amount of $Yb_2O_3$ were studied. As a result of the TG-DTA, exothermic peak was observed at around $670^{\circ}C$ due to the formation of the polycrystalline perovskite phase. All BSCT thick films showed XRD patterns of typical cubic peroveskite structure. The average thickness of BSCT thick films was about $70^{\mu}m$. The curie temperature and the dielectric constant decreased with increasing $Yb_2O_3$ doped content and the relative dielectric constant of the specimen, doped with 0.5 mol% $Yb_2O_3$ at BSCT(54/36/10), showed a best value of 5018 at curie temperature.

Nicotiana tabacum과 N. glutinosa간 원형질체융합 식물체에 있어서 엽록체 DNA의 제한효소단편의 유형 (Endonuclease Restriction Patterns of Chloroplast DNA in Somatic Hybrids Obtained by Protoplast Fusion of Nicotiana tabacum and N. glutinosa)

  • 김준철
    • Journal of Plant Biology
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    • 제34권1호
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    • pp.37-43
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    • 1991
  • Nicotiana ($NR^{-}/SR^{+}$)과 N. glutinosa간 전기적 (0.5 MHz의 AC와 2 ms 동안 1 kV DC) 원형질체 융합에서 선발은 1.2mg/ml의 streptomycin이 첨가된 $MSNO_3$ 배지를 통하여 가능하였으며, 이 융합세포의 분열이 지속되어 형성된 녹색 세포괴를 얻었다. 이 녹색 세포괴에서 재분화된 4개의 식물 계통들은 꽃과 잎에서 모식물체의 특징을 보였으며, 엽조직의 peroxidase 동위효소 유형 분석에서도 양쪽 모식물체의 특성을 갖고 있었다. XhoI의 제한효소 절단에 의해 융합식물체 계통의 엽록체 DNA의 분석에서도 융합체 식물계통들은 N. tabacum과 N. glutinosa에서 공통되는 단편과 모식물체 유래 단편을 보였고, 이 융합식물계통들 중 한 계통은 9개의 공통 단편에 N. tabacum의 1개 단편, N. glutinosa의 2개 단편이 추가되어 있는 유형을 보여 N. tabacum과 N. glutinosa의 엽록체 게놈을 모두 소유하고 있다는 것을 보여주었다.

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Optical, thermal and gamma ray attenuation characteristics of tungsten oxide modified: B2O3-SrCO3-TeO2-ZnO glass series

  • Hammam Abdurabu Thabit;Abd Khamim Ismail;M.I. Sayyed;S. Hashim;I. Abdullahi;Mohamed Elsafi;K. Keshavamurthy;G. Jagannath
    • Nuclear Engineering and Technology
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    • 제56권1호
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    • pp.247-256
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    • 2024
  • The glass series modified by tungsten oxide was created using the compounds (75-x) B2O3- 10SrCO3- 8TeO2- 7ZnO - xWO3, where x = 0, 1, 5, 10, 22, 27, 34, and 40% mole percentage. A UV-visible spectrophotometer and thermogravimetric-differential thermal analysis (TG-DTA) methods were employed to characterize the specimen's optical and phase transition attributes, respectively. The mass-attenuation coefficient (AC) of all created glasses from BSTZW0 to BSTZ7 was estimated using Geant4 code from 0.05 to 3 MeV and compared to the XCOM software results, with a relative difference of less than 2% between the two results. The increase of WO3 percentage lead to an increase in the Linear-AC at each studied energy, and this is mainly due to the fact that the higher the percentage of WO3 in the glass increases its density which causes an increase in the Linear-AC, so an energy of 0.06 MeV, as an example, the values of the Linear-AC was 4.009, 4.509, 5.442, 6812, 8.564, 9.856, 10.999 and 11.628 cm-1 form BSTZW0 too BSTZW7, respectively. The Half-VL (value layer), Mean-FP (free path), Tenth-VL, and Radiation attenuation performance (RAP) were also calculated for the current BSTZW-glass samples and revealed that BSTZW7 had the best gamma ray attenuation performance at all discussed energies when compared to other studied glass samples.

콘크리트를 통한 핵종의 확산계수

  • 금동권;조원진;한필수
    • Nuclear Engineering and Technology
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    • 제29권6호
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    • pp.17-28
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    • 1997
  • 콘크리트를 통한 핵종의 확산계수는 처분장으로 부터의 핵종 유출을 평가하는데 중요한입력 인자이다. 본 연구에서는 콘크리트에서의 핵종확산 연구 현황 및 핵종화산에 미치는 주요 인자들의 영향 등이 조사되었고, 주요 핵종의 확산계수가 직접 측정되었다. 내부확산법으로 측정된 확산계수값은 시료의 물과 시멘트 비 (W/C)가 증가할수록 증가하였으나 거의 같은 승수내에 있었으며, 공극확산이 핵종이동을 지배하였다. Cs 과 I 의 겉보기 확산계수는 순수 시멘트에서 각각 $1.0{\times}10^{-12}~1.0{\times}10^{-11}m^2/s$$3.0{\times}10^{-14}~1.0{\times}10^{-13}m^2/s$, 몰타르에서는 각각 $3.0{\times}10^{-12}~9.0{\times}10^{-11}m^2/s$$3.0{\times}10^{-11}m^2/s$의 범위에 있었다. 이와 병행하여 시멘트, 몰타르 및 콘크리트에서의 주요 방사성핵종의 확산계수 값을 문헌으로부터 수집, 정리하였다. 대상 핵종은 Cs, I, Sr, C, Co, H, Am, PU, Ni, Mn, Fe, Nb 및 Tc로서 수집된 핵종확산계수 값은 시료의 조건 (공극률 밀도, W/C 비, 온도 등) 에 따라 큰 편차를 보여주고 있다.

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Effect of Partial Substitution of Magnetic Rare Earths for La on the Structure, Electric Transport And Magnetic Properties of Oxygen Deficient Phase LaSr2MnCrO7-δ

  • Singh, Devinder;Sharma, Sushma;Mahajan, Arun;Singh, Suram;Singh, Rajinder
    • Bulletin of the Korean Chemical Society
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    • 제34권6호
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    • pp.1679-1683
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    • 2013
  • Intergrowth perovskite type complex oxides $La_{0.8}Ln_{0.2}Sr_2MnCrO_{7-{\delta}}$ (Ln=La, Nd, Gd, and Dy) have been synthesized by sol-gel method. Rietveld profile analysis shows that the phases crystallize with tetragonal unit cell in the space group I4/mmm. The unit cell parameters a and c decrease with decreasing effective ionic radius of the lanthanide ion. The magnetic studies suggest that the ferromagnetic interactions are dominant due to $Mn^{3+}$-O-$Mn^{4+}$ and $Mn^{3+}$-O-$Cr^{3+}$ double exchange interactions. Both Weiss constant (${\theta}$) and Curie temperature ($T_C$) increase with decreasing ionic radius of lanthanide ion. It was found that the transport mechanism is dominated by Mott's variable range hopping (VRH) model with an increase of Mott localization energy.