• The Korean Journal of Ceramics
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• 제6권1호
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• pp.47-52
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• 2000

Lanthanides such as La, Gd and Ce have recognized as elements of high level radioactive wastes immobilized by forming solid solution with $CaTiO_3$. For easy forming solid solution between $CaTiO_3$and lanthanides, the combustion synthesis process was applied and the powder characteristics and sinterability were investigated. The proper selection of the type and the composition of fuels are important to get the crystalline solid solution of $CaTiO_3$and lanthanides. When glycine or the mixtures of urea and citric acid with stoichiometric composition was used as a fuel, the solid solution of $CaTiO_3$with $La_2O_3$or $Gd_2O_3$or $CeO_2$was produced very well by the combustion process. The combustion synthesized powder seemed to have a good sinterability with the linear shrinkage of more than 25% up to $1500^{\circ}C$, while that of the solid state reacted powder was less than 10% at the same condition.

• 대한방사성의약품학회지
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• 제7권2호
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• pp.69-77
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• 2021

No-carrier-added holmium-166 (n.c.a ¹⁶⁶Ho) separation is performed based on the results of separation conditions using stable isotopes dysprosium (Dy) and holmium (Ho) to minimize radioactive waste from separation optimization procedures. Successful separation of two adjacent lanthanides was achieved by cation-exchange chromatography using a sulfonated resin in the H+ form (BP-800) and α-hydroxyisobutyric acid (α-HIBA) as eluent. For the identification process after separation of stable isotopes, the use of chromogenic reagents alternatively enables on-line detection because the lanthanides are hardly absorb light in the UV-vis region or exhibit radioactivity. Four different chromogenic reagents were pre-tested to evaluate suitable coloring reagents, of which 4-(2-Pyridylazo)resorcinol is the most recommendable considering the sensitivity and specificity for lanthanides. Lanthanide radioisotopes (RI) were monitored for separation with an RI detector using a lab-made separation LC system. Under the proper separation conditions, the n.c.a ¹⁶⁶Ho was effectively obtained from a large amount of 100 mg dysprosium target within 2 hrs.

• 한국세라믹학회지
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• 제43권11호
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• pp.688-692
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• 2006

Ferroelectric lanthanides-substituted $Bi_4Ti_3O_{12}$ $(Bi_{4-x}Ln_xTi_3O_{12}, BLnT)$ thin films approximately 200 nm in thickness were deposited by metal organic chemical vapor deposition onto Pt(111)/Ti/SiO$_2$/Si(100) substrates. Many researchers reported that the lanthanides substitution for Bi in the pseudo-perovskite layer caused the distortion of TiO$_6$ octahedron in the a-b plane accompanied with a shift of the octahedron along the a-axis. In this study, the effect of lanthanides (Ln=Pr, Eu, Gd, Dy)-substitution and crystallization temperature on their ferroelectric properties of bismuth titanate $(Bi_4Ti_3O_{12}, BIT)$ thin films were investigated. As BLnT thin films were substituted to lanthanide elements (Pr, Eu, Gd, Dy) with a smaller ionic radius, the remnant polarization (2P$_r$) values had a tendency to increase and made an exception of the Eu-substituted case because $Bi_{4-x}Eu_xTi_3O_{12}$ (BET) thin films had the smaller grain sizes than the others. In this study, we confirmed that better ferroelectric properties can be expected for films composed of larger grains in bismuth layered peroskite materials. The crystallinity of the thin films was improved and the average grain size increased as the crystallization temperature,increased from 600 to 720$^{\circ}C$. Moreover, the BLnT thin film capacitor is characterized by well-saturated polarization-electric field (P-E) curves with an increase in annealing temperature. The BLnT thin films exhibited no significant degradation of switching charge for at least up to $1.0\times10^{11}$ switching cycles at a frequency of 1 MHz. From these results, we can suggest that the BLnT thin films are the suitable dielectric materials for ferroelectric random access memory applications.

• Bulletin of the Korean Chemical Society
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• 제33권11호
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• pp.3871-3874
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• 2012

• 대한화학회지
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• 제35권5호
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• pp.520-526
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• 1991

Dinonylnaphthalene sulfonic acid(DNNS) 양이온 교환체와 tartaric acid 착화제를 이용하는 동적계에서 희토류원소의 용리거동을 연구하였다. 등용매 용리에서 logK' vs log$[NH^{4+}]$ 및 logK' vslog[tar-tarate]의 관계가 직선으로 나타났다. Tartaric acid에 대한 기울기 용리에서 logK' vs logR의 관계의 기울기값은 초기 농도가 낮을수록 증가하였다. DNNS 이온교환체에서 히토류 원소의 분리관 효율 및 분해능은 tartaric acid 용리제보다 ${\alpha}$-hydroxyisobutyric acid 용리제가 더 우수한 결과를 주었다.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1999년도 추계학술발표회요약집
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• pp.304.2-304
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• 1999

• Bulletin of the Korean Chemical Society
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• 제14권2호
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• pp.165-166
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• 1993

• 대한화학회지
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• 제7권4호
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• pp.245-250
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• 1963

TBPO와 TOPO와의 混合溶媒(稀釋制 : toluene)에 依한 三假狀態의 4f 稀土類元素의 抽出에 있어 相乘效果(synerigistic effect)가 나타남을 알았으며 이것은 各 單獨溶媒系에 있어서 生成抽出되는 $M(NO_3)_3\;(TBPO)_3$ 및 $M(NO_3)_3\;(TOPO)_3$型 外에 $M(NO_3)_3\;(TBPO)_2\;(TOPO)$型이 새로히 追加生成됨을 起因된 것으로 認定된다.

• 대한화학회지
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• 제34권3호
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• pp.280-287
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• 1990

란탄나이드 3가 [Sm(Ⅲ), Tb(Ⅲ), and Yb(Ⅲ)]와 유기리간드들의 착물을 비수용매 속에서 전기화학적인 DC 및 DP 폴라로그래피 그리고 CV방법으로 조사하였다. 란탄나이드 3가 착물들은 Ag/AgCl 전극에서 이들 환원 peak는$ E_{pc}$ = -0.16 V, -0.35 V, -0.14 V와 그리고 -0.03 V의 비가역적인 일전자환원 과정이었고, 무거운 란탄나이드의 거동은 원자번호가 증가함에 따라서 안정도상수는 Sm > Tb > Ho > Yb순서로 감소하였다

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2001년도 추계학술발표회요약집
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• pp.297.1-297
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• 2001