• 제목/요약/키워드: manganese powder

검색결과 80건 처리시간 0.026초

La0.8Ca0.2MnO3의 합성 및 특성연구 (Preparation and Characterization of La0.8Ca0.2MnO3)

  • 정미원;이지윤;김현정
    • 한국세라믹학회지
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    • 제40권5호
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    • pp.434-440
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    • 2003
  • 초거대 자기 저항 물질인 페로브스카이트 L $a_{0.8}$C $a_{0.2}$Mn $O_3$의 분말을 졸-겔방법으로 제조하였다. Lanthanum(III), Calcium(II) 그리고 Manganese(III) 2,4-Pentanedionate를 Propionic acid와 methane떠 혼합용매를 사용하고 PEG (l5 wt%) 용액을 첨가 하여 안정한 졸용액을 합성하였고 FT-IR spectroscopy로 반응의 진행 정도를 관찰하였다. L $a_{0.8}$C $a_{0.2}$Mn $O_3$ 겔 분말에 대해 온도를 변화시키면서 열처리하여 FT-IR, CP/MAS $^{13}$C solid state NMR spectroscopy와 XRD등을 이용해 구조변화를 관찰하였다. 열분석은 TG/DTA로 측정하였으며, FE-SEM을 통해 입자크기와 균일도를 관찰하였고, 양이온 조성 비율을 알아보기 위해 ICP-AES를 측정하였다. 자성 특성을 규명하기 위해 VSM을 이용하여 자기 모멘트를 측정하였으며, 상자기성 에서 강자기성으로 전이되는 큐리온도( $T_{c}$)를 관찰하였다.

XRD와 XRF를 이용한 무명이(無名異)의 구성 성분 연구 (A Study on the Constituents of Pyrolusitum by XRD and XRF)

  • 이민우;최고야;이영종
    • 대한본초학회지
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    • 제33권6호
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    • pp.87-92
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    • 2018
  • Objectives: The aim of the study was to analyze the constituents of Pyrolusitum, which was used to eliminate static blood and inflammation, to establish the basis of clinical application. Methods: Qualitative analysis was performed by X-Ray Diffraction (XRD) using the sample as a powder, and the elemental content of granular sample was measured by X-Ray Fluorescence (XRF). 1 M hydrochloric acid and 5% sodium hydroxide aqueous solution were added to observe the changing shape, respectively. Results: Qualitative analysis by XRD revealed that the Pyrolusitum samples used in the study contained quarts and kaolinite. Quantitative analysis by XRF revealed that the manganese content in the samples used in the study was 6.16% on average, while iron was contained the highest amount of 22.99%. The minor constituents include 1.08% of titanium, 0.30% of barium, 0.18% of lead, 0.06% of zirconium, 0.05% of chromium, 0.04% of zinc, 0.03% of cadnium, 0.02% of nickel, 0.01% of arsenic, 0.01% of copper, 0.01% of rubidium, 0.01% of strontium, 0.00% of molybdenum, respectively. And cobalt, which is reported to be a constituent of Pyrolusitum, was not detected at all in the samples of the study. Pyrolusitum was dissolved in dark brown when it was put into 1 M hydrochlorid acid, and there was brown precipitate when sodium hydroxide solution was added to Pyrolusitum and stirred. Conclusions: It was found that manganese and iron were the major constituents of Pyrolusitum, and it could be identified by using concentrated hydrochloric acid and sodium hydroxide solution.

용액 플라즈마를 이용한 콜로이드 및 나노 구조 MnO2의 친환경 합성 (Green Synthesis of Colloidal and Nanostructured MnO2 by Solution Plasma Process)

  • 김혜민
    • 한국재료학회지
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    • 제33권7호
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    • pp.315-322
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    • 2023
  • In the present work, we address the new route for the green synthesis of manganese dioxide (MnO2) by an innovative method named the solution plasma process (SPP). The reaction mechanism of both colloidal and nanostructured MnO2 was investigated. Firstly, colloidal MnO2 was synthesized by plasma discharging in KMnO4 aqueous solution without any additives such as reducing agents, acids, or base chemicals. As a function of the discharge time, the purple color solution of MnO4- (oxidation state +7) was changed to the brown color of MnO2 (oxidation state +4) and then light yellow of Mn2+ (oxidation state +2). Based on the UV-vis analysis we found the optimal discharging time for the synthesis of stable colloidal MnO2 and also reaction mechanism was verified by optical emission spectroscopy (OES) analysis. Secondly, MnO2 nanoparticles were synthesized by SPP with a small amount of reducing sugar. The precipitation of brown color was observed after 8 min of plasma discharge and then completely separated into colorless solution and precipitation. It was confirmed layered type of nanoporous birnessite-MnO2 by X-ray powder diffraction (XRD), fourier-transform infrared spectroscopy (FT-IR), and electron microscopes. The most important merits of this approach are environmentally friendly process within a short time compared to the conventional method. Moreover, the morphology and the microstructure could be controllable by discharge conditions for the appropriate potential applications, such as secondary batteries, supercapacitors, adsorbents, and catalysts.

에칭 폐액으로부터 용매추출과 가수분해를 이용한 니켈분말제조에 관한 연구 (Recovery of Nickel from Waste Iron-Nickel Alloy Etchant and Fabrication of Nickel Powder)

  • 이석환;채병만;이상우;이승환
    • 청정기술
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    • 제25권1호
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    • pp.14-18
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    • 2019
  • 여러 금속 부품을 가공하기 위하여 사용된 염화제이철 에칭 폐액은 유가금속인 니켈 등을 함유하고 있다. 본 연구에서는 식각공정을 완료한 에칭폐액을 재생하고 부산물로 나온 니켈 함유 폐액으로부터 정제하여 니켈 금속분말로 제조하는 공정을 개발하였다. 부산물인 니켈함유용액을 철 등의 불순물을 침전 제거하기 위하여 수산화나트륨 수용액을 실험을 통하여 가수분해 중화제로서 선정하였고, 이를 통하여 철 등의 불순물을 pH = 4 조건하에 침전 제거하였다. 그 후, 불순물로 잔류하는 망간 및 아연과 같은 금속이온들을 D2EHPA (Di-(2-ethylhexyl) phosphoric acid)를 사용하여 용매추출 하였다. 정제된 염화니켈은 99% 이상의 순도를 가지고 있으며, 그 후 환원제로 하이드라진을 이용하여 99% 이상의 순도와 약 150 nm의 크기를 가지는 니켈 금속분말로 제조하였다. 염화니켈 및 니켈 금속분말의 성분은 EDTA 적정법과 유도결합 플라즈마 방출분광법(inductively coupled plasma optical emission spectrometer, ICP-OES)을 이용하여 확인하였으며, 전계방사 주사전자현미경(field emission scanning electron microscope, FE-SEM), X-선 회절분석기(X-ray diffraction, XRD) 및 투과전자현미경(transmission electron microscopy, TEM)을 통하여 금속분말의 형태, 입자 크기 및 결정성과 같은 물리적 특성을 확인하였다.

한국에서 유통 중인 산화형 염모제의 중금속 농도에 관한 연구 (A Study on Heavy Metal Concentrations of Oxidized Hair Coloring Products in Korea Market)

  • 최채만;홍미선;이윤정;김화순;김현정;김정헌;채영주
    • 대한화장품학회지
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    • 제39권3호
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    • pp.241-249
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    • 2013
  • 2012년 1월에서 10월 사이에 전국에서 유통 중인 산화형 염모제(1제) 125개 제품에서 납(Pb), 비소(As), 카드뮴(Cd), 크롬(Cr), 망간(Mn), 니켈(Ni), 구리(Cu)의 농도 측정과 국산, 수입산 및 헤나별, 성상별, 색상별로 비교해 봄으로써 이에 관련된 분야의 기초자료를 제공하고자 본 연구를 시행하였다. 분석된 전체 염모제의 평균 중금속 농도는 납 0.211 ${\mu}g/g$, 비소 0.051 ${\mu}g/g$, 카드뮴 0.008 ${\mu}g/g$, 크롬 0.954 ${\mu}g/g$, 망간 6.250 ${\mu}g/g$, 니켈 0.591 ${\mu}g/g$, 구리 0.544 ${\mu}g/g$으로 측정되었으며 납, 비소의 경우 우리나라 화장품 안전기준 등에 관한 규정에서 허용기준인 납 20 ${\mu}g/g$, 비소 10 ${\mu}g/g$보다 낮은 수치이다(식품의약품안전처 고시 제2013-24 호). 또한 헤나 염모제는 통계적으로 유의한 차이를 보였으며(p < 0.05), 납 1.264 ${\mu}g/g$, 비소 0.267 ${\mu}g/g$, 카드뮴 0.025 ${\mu}g/g$, 크롬 4.055 ${\mu}g/g$, 망간 72.044 ${\mu}g/g$, 니켈 3.076 ${\mu}g/g$, 구리 4.640 ${\mu}g/g$으로 국산 및 수입 염모제보다 높았다. 염모제의 성상별 중금속 농도는 통계적으로 유의한 차이를 보였으며(p < 0.05), 크림과 액체 타입에서 크롬이 각각 0.708 ${\mu}g/g$, 0.478 ${\mu}g/g$로 가장 높았고, 분말타입에서는 망간이 60.041 ${\mu}g/g$로 높았다. 염모제의 색상별 중금속 농도는 통계적으로 유의한 차이를 보이지 않았으며, 노란색의 경우 납, 크롬이 높은 평균 농도를 보였고, 적색과 분홍색의 염모제는 크롬, 갈색과 흑색은 망간이, 녹색은 니켈이 높은 평균 농도를 나타내었다.

침전-증발법에 의해 제조된 리튬이온 2차 전지용 LiMn2O4 양극재료의 특성 (Characteristics of LiMn2O4 Cathode Material Prepared by Precipitation-Evaporation Method for Li-ion Secondary Battery)

  • 김국태;윤덕기;심영재
    • 한국재료학회지
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    • 제12권9호
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    • pp.712-717
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    • 2002
  • New wet chemical method so called precipitation-evaporation method was suggested for preparing spinel structure lithium manganese oxide ($LiMn_2$$O_4$) for Li ion secondary battery. Using precipitation-evaporation method, $LiMn_2$$O_4$ cathode materials suitable for Li ion secondary batteries can be synthesized. Single spinel phase $LiMn_2$$O_4$ powder was synthesized at lower temperature compared to that of prepared by solid-state method. $LiMn_2$$O_4$ powder prepared by precipitation-evaporation method showed uniform, small size and well defined crystallinity particles. Li ion secondary battery using $LiMn_2$$O_4$ as cathode materials prepared by precipitation-evaporation method and calcined at $800^{\circ}C$ showed discharge capacity of 106.03mAh/g and discharge capacity of 95.60mAh/g at 10th cycle. Although Li ion secondary battery showed somewhat smaller initial capacity but good cyclic ability. It is suggested that electro-chemical properties can be improved by controlling particle characteristics by particle morphology modification during calcination and optimizing Li ion secondary battery assembly conditions.

Cr2O3 및 Mn2O3의 코팅에 의한 Core-Shell 구조의 BaTiO3 분말 제조 (Preparation of Core-Shell Structured BaTiO3 Powder Via Coating of Cr2O3 and Mn2O3)

  • 권병수;이혜은;장정윤;이상길;정인재;조영상;박태진;최광진
    • Korean Chemical Engineering Research
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    • 제46권1호
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    • pp.99-105
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    • 2008
  • 본 연구에서는 MLCC용 $BaTiO_3$에 첨가되는 $Cr_2O_3$$Mn_2O_3$의 나노코팅에 의한 core-shell 구조의 $BaTiO_3$ 분말을 제조하였다. 예비실험을 통해서 $KMnO_4$$K_2Cr_2O_4$ 그리고 sulfur를 사용하는 최적의 액상반응조건이 확립되었다. 본 연구에서는 두 첨가제 분말을 합성하였고 동일한 반응조건으로 두 첨가제를 $BaTiO_3$ 분말표면에 코팅하였다. 코팅은 one-step과 two-step의 두 방법으로 구분하여 시행하였고 그 결과를 분석 비교하였다. 결론적으로 말해서, $Cr_2O_3$$Mn_2O_3$의 두 첨가제는 용이한 반응조건에서 높은 수율로 우수한 품질의 코팅막을 형성하므로써, 첨가제 함량과 코팅막 특성의 정밀한 조절이 용이함을 보여주었다.

Superconducting magnetic separation of ground steel slag powder for recovery of resources

  • Kwon, H.W.;Kim, J.J.;Ha, D.W.;Choi, J.H.;Kim, Young-Hun
    • 한국초전도ㆍ저온공학회논문지
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    • 제19권1호
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    • pp.22-25
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    • 2017
  • Steel slag has been considered as an industrial waste. A huge amount of slag is produced as a byproduct and the steel slag usually has been dumped in a landfill site. However the steel slag contains valuable resources such as iron, copper, manganese, and magnesium. Superconducting magnetic separation has been applied on recovery of the valuable resources from the steel slag and this process also has intended to reduce the waste to be dumped. Cryo-cooled Nb-Ti superconducting magnet with 100 mm bore and 600 mm of height was used as the magnetic separator. The separating efficiency was evaluated in the function of magnetic field. A steel slag was ground and analyzed for the composition. Iron containing minerals were successfully concentrated from less iron containing portion. The separation efficiency was highly dependent on the particle size giving higher separating efficiency with finer particle. The magnetic field also effects on the separation ratio. Current study showed that an appropriate grinding of slag and magnetic separation lead to the recovery of metal resources from steel slag waste rather than dumping all of the volume.

Preparation of Graphene Based PdOx and CuOx/MnOx Nanocomposites and Their Catalytic Applications in C-C Coupling and CH3SH Decomposition Reactions

  • 이경훈;박준범
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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    • pp.175.2-175.2
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    • 2014
  • Graphene (G) has been modified with palladium, copper, and manganese oxide nanoparticles (NPs), and their catalytic applications have been studied in C-C coupling reactions and methylmercaptan (CH3SH) decomposition reactions. In this research, graphite oxide (GO) sheets were exfoliated and oxidized from graphite powder and impregnated with metal precursors including Pd2+, Cu2+, and Mn2+. The thermal treatments of the metal impregnated GO in preferred gas environments produced Pd NPs on graphene (Pd/G), PdO NPs on GO (PdO/GO), and CuOx and MnOx NPs on graphene (CuOx/MnOx/G). In case of Pd/G and PdO/GO, the TEM images show that, although the mean size of the Pd NPs changed significantly before and after the C-C coupling reaction, that of the PdO NPs didn't, implying that the PdO/GO was superior to Pd/G in terms of the recyclability. Also, we demonstrate that the CuOx/MnOx/G exerts the excellent catalytic efficiency in CH3SH decomposition reaction comparing with conventional catalysts. The chemical and electronic structural changes were investigated using XRD and XPS.

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Metal-Insulator Transition Induced by Short Range Magnetic Ordering in Mono-layered Manganite

  • Chi, E.O.;Kim, W.S.;Hong, C.S.;Hur, N.H.;Choi, Y.N.
    • Bulletin of the Korean Chemical Society
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    • 제24권5호
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    • pp.573-578
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    • 2003
  • The structural, magnetic, and transport properties of a mono-layered manganite $La_{0.7}Sr_{1.3}MnO_{4+{\delta}}$ were investigated using variable temperature neutron powder diffraction as well as magnetization and transport measurements. The compound adopts the tetragonal I4/mmm symmetry and exhibits no magnetic reflection in the temperature region of 10 K ≤ T ≤ 300 K. A weak ferromagnetic (FM) transition occurs about 130 K, which almost coincides with the onset of a metal-insulator (M-I) transition. Extra oxygen that occupies the interstitial site between the [(La,Sr)O] layers makes the spacing between the [MnO₂] layers shorten, which enhances the inter-layer coupling and eventually leads to the M-I transition. We also found negative magneto resistance (MR) below the M-I transition temperature, which can be understood on the basis of the percolative transport via FM metallic domains in the antiferromagnetic (AFM) insulating matrix.