• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
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• pp.581-584
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• 2002

A new method for the preparation of lanthanide ions activated strontium aluminates phosphor by combustion method has been proposed. Combustion method consist of the redox reactions between the respective metal nitrates and urea in a preheated funace at $500^{\circ}C$. The luminescence behavior of the phosphor was studied and compared with corresponding phosphor prepared by conventional method. Effect of $Mg^{2+}$ ion concentration in strontium aluminate phosphor was investigated and the maximum luminescence of about $100cd/m^2$ was obtained. This method gave better brightness and small size to the phosphor than made by conventional method.

• The Korean Journal of Ceramics
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• 제6권4호
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• pp.370-379
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• 2000

Simple ways to build up mixed-metal molecules which can act as potential single-source precursors to multimetallic oxides are reviewed. Emphasis is given to Lewis acid-base reactions between metal alkoxides M(OR)/sub n/, and between metal alkoxides and more accessible oxide precursors, carboxylates M(O₂CR)/sub n/ and β-diketonates M(β-dik)/sub n/. Characterization of the precursors is achieved in the solid state (single crystal X-ray diffraction, FT-IR) and by multinuclear NMR in solution. The reactions proceed toward the formation of aggregates in which the different metals display their usual coordinations numbers, often six for transition metals, as shown. Strategies for fixing the stoichiometry between the metals are developed. The reactivity of the MM species (dissociation, effects of chemical modifiers, of other metallic species, hydrolytic or non-hydrolytic condensation, etc.) will be indicated. Transformations into oxides are illustrated on precursors for titanates or niobates.

• Bulletin of the Korean Chemical Society
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• 제15권9호
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• pp.782-785
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• 1994

The dissociation kinetics of linear polyaminopolycarboxylate complexes of lanthanide ions (L$n^{3+}: Ce^{3+},\;Eu^{3+}\;and\;Yb^{3+}$) has been studied in an aqueous solution of 0.10 M (NaCl$O_4$) at 25.0${\pm}0.1^{\circ}C$ using Cu(II) ions as a scavenger. The dissociation rates of acid-catalyzed pathway decrease in the order Ln(EPDTA$)^- > Ln(DPOT)^- > In(TMDTA)^- > Ln(MPDTA)^- > Ln(EDTA)^- > Ln(PDTA)^- > Ln(DCTA)^-$ according to the present and literature data. An increase in the N-Ln-N chelate ring from 5 to 6 and substitution of two methyl groups, one ethyl and hydroxyl group on a chelate ring carbon of these ligands leads to a decrease in kinetic stabilities of the complexes. The substitution of one methyl group and cyclohexyl ring on a ring carbon, however, results in a significant increase in the kinetic stability of the resulting $Ln^{3+}$ complexes. Individual reaction steps taking place for each system, with different copper, acetate buffer concentration and pH dependence, are also discussed.

• Journal of Magnetics
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• 제18권3호
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• pp.365-369
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• 2013

Coal ash is known to contain a noticeable amount of valuable elements, including transition metals and lanthanides. Therefore it is quite actual problem to extract them for metallurgy and other applications. This paper presents the results of high gradient magnetic and mechanical separation, microscopy, element analyses and optical spectroscopy of brown coal ash taken from the combustion camera and chimney-stalk of Angren thermal power station. The separated magnetic fraction was 3.4 wt.%, where the content of Fe in ferrospheres increased to 58 wt.%. The highest contents of Fe and rare earth elements were found in the fine fractions of $50-100{\mu}m$. Optical absorption spectroscopy of water solutions of the magnetic fractions revealed $Fe^{2+}$ and $Fe^{3+}$ ions in the ratio of ~1:1. The separated coal ash could be used for cleaning of technological liquid waste by means of the high gradient magnetic field.

• Bulletin of the Korean Chemical Society
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• 제4권5호
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• pp.231-234
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• 1983

The stability constant for the complex of $UO_2^{2+}$ with a macrocyclic aminoether ligand, 1,7,10,16-tetraoxa-4,13-diazacyclooctadecane, has determined in aqueous solution. The conductivity and pH metric measurements suggest that the ligand forms a stable 1:1 complex with $UO_2^{2+}$ ion, and the complex is an ionic form, $UO_2L^{2+}$, in aqueous solution. The fact that the ligand does not form a complex with lanthanides, such as $Ce^{3+}$, $Sm^{3+}$, and $Nd^{3+}$ ions, in aqueous solution suggests a possibility of separation of the lanthanide elements from uranium matrix using the macrocyclic aminoether ligand.

• Bulletin of the Korean Chemical Society
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• 제8권5호
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• pp.366-372
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• 1987

Cryptand[2,2] was grafted to low crosslinked styrene-divinylbenzene copolymer by substitution reaction with chloromethylated styrene-divinylbenzene copolymer. This resin was stable in concentrated acid and base, and showed a good resistance to heat. The pH, time, and concentration dependence of the adsorption of metal ions by this resin were studied. Studies on the chromatographic separation of lanthanides, $Cu^{2+}$ and $UO_2^{2+_2}$ were also carried out with various eluents. These studies demonstrate that this resin has the applicability to the preconcentration and separation of metal ions.

• 분석과학
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• 제5권3호
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• pp.249-261
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• 1992

무거운 란탄족 이온($Gd^{3+}$, $Tb^{3+}$, $Dy^{3+}$, $Ho^{3+}$, $Er^{3+}$, $Tm^{3+}$, $Yb^{3+}$ 및 $Lu^{3+}$)과 alixarin red S(ARS) 사이에 생성한 착물의 전기화학적 거동을 직류폴라로그래피, 펄스차폴라로그래피 및 순환전압전류법으로 연구하였다. 0.1M LiCl 지지전해질 용액에서 착화제인 ARS는 2전자 1단계의 가역성환원반응으로 $30^{\circ}C$까지는 확산 지배적이었으며 전극반응에서 흡착이 거의 일어나지 않았다. 란탄족 이온과 ARS는 1:3 착물을 형성하였으며 이 착물의 환원파는 펄스차이폴라로그래피 및 순환전압전류법으로 흡착성 착물파임을 확인하였다. 착물파의 환원전위는 ARS의 환원파보다 음전위에서 나타났으며 란탄족이온의 농도의 증가에 따른 ARS의 봉우리전류($P_1$)의 감소와 착물의 봉우리전류($P_2$)의 증가는 pH=9.5, 0.1M LiCl 및 ARS의 농도 $1{\times}10^{-3}M$일 때 란탄족 이온의 농도 $2{\times}10^{-6}M{\sim}6.4{\times}10^{-5}M$ 범위에서 직선적으로 변화하였다.

• 대한화학회지
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• 제31권4호
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• pp.328-333
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• 1987

$C_18$ 역상 충전제에 1-eicosylsulfate($C_{20}H_{41}SO_4^-$)를 흡착하는 조건을 조사하였으며 $1.46{\times}10^{-4}M$의 흡착용액(25% 아세토니트릴 수용액) 1.2l를 통과시켰을 때 흡착평형이 일어났다. 이 분리관은 0.05 M ${\alpha}$-HiBA 용리액 10l까지 안정하였으며 Eu, Nd, Ce , La에 대한 분리관효율은 0.15M ${\alpha}$-HiBA 용리액 1.0ml/min에서 약 0.04 mm의 HETP를 나타내었다. 이 흡착분리관으로 희토류 원소 및 전이원소들을 개별 분리하였다.

• 대한화학회지
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• 제34권6호
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• pp.616-621
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• 1990

UV-VIS 흡광광도법으로 Nd, Pr, Sm, Eu, Ho 및 Er을 정량할 때 스펙트럼 방해를 다원소 보정법으로 방법에 대하여 연구하였다. 개별희토류의 흡광도를 측정하고 또, Nd와 Pr의 혼합용액 및 Sm, Eu, Ho, Er의 혼합용액의 흡광도를 측정하여 몰흡광 계수를 구하고 이들로부터 상호 방해가 가장 적은 파장 즉, Nd(444.2nm), Pr(575.1nm), Sm(401.7nm), Eu(394.2nm), Ho(416.6nm), Er(379.7 nm)임을 알았다.

• Nuclear Engineering and Technology
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• 제31권5호
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• pp.498-505
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• 1999

Trivalent actinide-lanthanide group separation is difficult to perform on an industrial scale, because of the many drawbacks of the available chemical process. In this paper, picolinamide(C$_{8}$H$_{17}$) is synthesized and characterized, and extraction yields of Am-241, Eu-152 and Nd are determined in batch extraction experiments. In particular, the influence of the solvent is described. The extraction yields of Am-241, Eu-152 and Nd depended on the LiNO$_3$ concentration, the picolinamide(C$_{8}$H$_{17}$) concentration and the acidity. A favorable picolinamide(C$_{8}$H$_{17}$) concentration was found to be about 2M. The appropriate nitric acid concentration and LiNO$_3$ concentration were confirmed to be about 0.125M and 3M, respectively. The separation factor of Am and Eu was about 9.9 at optimum conditions. The picolinamide(C$_{8}$H$_{17}$) is a very promising extractant for the actinide(III)-lanthanides(III) separation.aration.aration.