• Proceedings of the Korean Radioactive Waste Society Conference
• /
• 2009.11a
• /
• pp.346-346
• /
• 2009

산화물 형태 사용후핵연료의 효율적 처분 혹은 재활용을 위한 연구 가운데, 고온의 LiCl 용융염 중에서 전해환원하여 금속으로 환원시킨 후, 환원된 금속을 고온의 LiCl-KCl 용융염에서 전해정련하는 연구가 국내외적으로 활발하게 진행되고 있다. 전해환원을 위해 일정 농도 $Li_2O$가 LiCl 용융염에 첨가되며 $Li_2O$ 농도가 높으면 반응 재질의 부식성이 크게 증가하므로 일반적으로 우라늄 산화물은 1wt% 이하의 $Li_2O$ 농도에서 전해환원 된다. 우라늄 산화물의 전해환원 전위는 $Li_2O$의 전해환원 전위 보다 표준 상태를 기준으로 공정온도인 650 $^{\circ}C$ 에서 약 70 mV 정도 낮기 때문에 전해환원 과정에서 $Li_2O$ 의 환원으로 Li 금속이 생성될 가능성이 있으며 우라늄 산화물은 대부분 직접 전해환원 되지만 일부 Li에 의해 화학적으로 환원되기도 한다. 전해환원 공정에서 환원되지 않은 희토류 산화물은 전해정련 공정에서 $UCl_3$와 반응하여 $UO_2$를 생성시켜 공정 효율을 떨어뜨린다. 따라서 전해환원 공정에서 가능하연 최대한 희토류 산화물을 금속으로 환원시키는 조건을 찾아내는 것이 바람직하고 이를 위해서 우선 전해환원 공정에서 희토류 산화물의 화학적 거동의 이해가 요구된다. 본 연구에서 열역학적 검토를 통하여 희토류 산화물의 환원 조건을 조사한 결과 희토류 산화물은 매운 낮은 $Li_2O$ 농도에서 Li에 의해 환원되고, 1wt% 이하의 $Li_2O$ 농도에서는 Sc와 Lu의 산화물이 $Li_2O$와 복합산화물을 형성하고 이들 복합산화물은 Li에 의해 환원되지 않는 것으로 나타났다. 또한 희토류 원소 별로 희토류 원소 산화물의 Li에 의한 환원 조건으로서 평형상태에서의 $Li_2O$ 농도 즉 환원 임계 $Li_2O$ 농도를 실험적으로 측정하였으며 1wt% $Li_2O$ 농도 이하에서 열역학적 해석과 동일하게 Sc와 Lu만이 복합산화물을 형성하여 Li에 의해 직접환원 되지 않는 것으로 관찰되었다.

• Proceedings of the Korean Radioactive Waste Society Conference
• /
• 2003.11a
• /
• pp.373-378
• /
• 2003

As a part of assessment of the structural material for the molten salt handling system, corrosion behavior of austenitic alloys, Fe-base and Ni-base in the molten salt of $LiCl-Li_2O_2$ was investigated in the range of temperature; 650~$725^{\circ}C$, time; 24- 168h, $Li_2O$; 3wt%, mixed gas; Ar-10%$O_2$. In the molten salt of $LiCl-Li_2O_2$, Ni-base alloys showed higher corrosion resistance than Fe-base alloys. Fe-base alloy with low Fe and high Ni contents exhibited better corrosion resistance. The scales of $Cr_2O_3$, $FeCr_2O_4$ on Fe-base alloys were showed, and $Cr_2O_3$, $NiFe_2O_4$ on Ni-base alloys were also showed.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.17 no.3
• /
• pp.347-353
• /
• 2019

The composition of the reduced fuel produced in the electrolytic reduction process of pyroprocessing affects the concentration change of $UCl_3$, an important operating variable of the electrorefining process. In this study, we examined the concentration change of $UCl_3$ in the electrorefiner according to the content of TRU and RE elements in the reduced fuel and the concentration of $Li_2O$ introduced in the electrorefiner accompanied with the reduced fuel. Considering only the TRU and RE elements, the concentration of $UCl_3$ decreased with increasing the number of electrorefining operation batch. In order to operate one campaign (20 batches) of electrorefining process, it was found that additional injection of $UCl_3$ should be conducted more than 3 times. On the other hand, the concentration of $UCl_3$ in the electrorefiner changed significantly depending on the concentration of $Li_2O$ and, accordingly the number of operable electrorefining batches decreased rapidly, showing that the concentration of $Li_2O$ is an important operating variable in electrorefining. Therefore, the results of this study show that to maintain the concentration of $UCl_3$ in the electrorefiner, the operation mode should be set by taking into account the effect of $Li_2O$ as well as the TRU and RE elements contained in the reduced fuel.

• Journal of the Korean Electrochemical Society
• /
• v.14 no.2
• /
• pp.98-103
• /
• 2011

[ $Li[Ni_{0.8}Co_{0.15}Al_{0.05}]O_2$ ]cathode material for lithium secondary battery is obtained using co-precipitation method. To determine the optimal metal solution concentration value, the CSTR coprecipitation was carried out at various concentration values(1-2 mol/L). The surface morphology of coated samples was characterization by SEM(scanning electron microscope) and XRD (X-Ray Diffraction)analyses. Impedance analysis and cyclic voltammogram presented that internal resistance of the cell was dependent upon the concentration of metal solution. such data is very helpful in determining the optimal content of metal solution concentration to enhancing electrochemical property by adjusting powder size distribution and crystal structure.

• Proceedings of the Korean Radioactive Waste Society Conference
• /
• 2004.06a
• /
• pp.285-291
• /
• 2004

As a part of assessment of the structural material for the molten salt handling system, corrosion behavior of Inconel 718, X-750, Haynes 75 and Haynes 263 alloys in the molten salt of LiCl-Li$_2$O-O$_2$was investigated in the range of temperature; $650^{\circ}C$, time; 24~168h, $Li_2O$; 3wt%, mixed gas; Ar~10%$O_2$. In the molten salt of LiCl-$Li_2O-O_2$, the order corrosion rate was Haynes 263 ＜ Haynes 75 ＜ Inconel X-750 ＜ Inconel 718. Haynes 263 alloy showed the highest corrosion resistance among the examined alloys. Corrosion products of alloys were as fellows: Haynes 75: $Cr_2O_4$, $NiFe_2O_4$, $LiNiO_2$, $Li_2NiFe_2O_4$, Inconel 718; $Cr_2O_4$, $NiFe_2O_4$, Haynes 263; $Li(Ni,Co)O_2$, $NiCr_2O_4$, $LiTiO_2$, Inconel X-750; $Cr_2O_3$, $NiFe_2O_4$,$FeNi_3$, (Al,Nb,Ti)$O_2$. Haynes 263 showed local corrosion behavior and Haynes 75, Inconel 718 and Inconel X-750 showed uniform corrosion behavior.

• Journal of the Korean Society of Radiology
• /
• v.9 no.3
• /
• pp.169-174
• /
• 2015

$LiGd_9(SiO_4)_6O_2:Ce^{3+}$ phosphors were synthesized by solid-state reaction method. The structural characteristic was investigated by X-ray powder diffraction analysis. The emission and excitation spectra of the $Ce^{3+}$ ions doped $LiGd_9(SiO_4)_6O_2$ phosphors were obtained under the UV excitation. The emission spectra of $LiGd_9(SiO_4)_6O_2:Ce^{3+}$ shows the band at 410 nm corresponding to the $^2F_{5/2}$ and $^2F_{7/2}$ states of $Ce^{3+}$. The red shift of $Ce^{3+}$ emission is found as the $Ce^{3+}$ concentration increases, which could be explained by the change in crystal-field symmetry and strength with increasing $Ce^{3+}$ concentration. Fluorescence decay time of $Ce^{3+}$ was about 20 ns. When the concentration of $Ce^{3+}$ increases life time was slightly reduced.

• Korean Journal of Materials Research
• /
• v.9 no.9
• /
• pp.896-899
• /
• 1999

A carbon dioxide gas sensor was studied as a function of temperature and $CO_2$concentration in the Li$_2$ZrO$_3$ system. Lithium zirconate(Li$_2$ZrO$_3$) was synthesized by the heat-treatment of zirconia(ZrO$_2$)and Lithium carbonate(Li$_2$CO$_3$). The specimens were prepared both as bulk disk, 10mm in diameter and 1.0mm thickness, and thick films on an alumina substrate. Lithium zirconate readily responded to $CO_2$concentration from 0.1% to 100% in the range of 45$0^{\circ}C$ to $650^{\circ}C$. The sensitivity to $CO_2$ was dependent on the measuring temperature. Lithium zirconate(Li$_2$ZrO$_3$) decomposes into Li$_2$CO$_3$ and ZrO$_2$after the reaction with $CO_2$in the range of 45$0^{\circ}C$ to $650^{\circ}C$. Li$_2$CO$_3$ changes into Li$_2$O and $CO_2$ above $650^{\circ}C$. The material showed difficulty with reversibility and recovery. The optimum temperature for the highest sensitivity is around 55$0^{\circ}C$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2009.06a
• /
• pp.452-452
• /
• 2009

HEV용 리튬 이차전지의 양극물질로서 $LiMn_2O_4$는 일반적으로 사용되고 있는 $LiCoO_2$에 비해 값이 저렴하고 독성이 낮으며, 높은 전압과 좋은 율 특성을 갖는 물질이다. 하지만 고온에서 전이금속인 Mn이 전해액으로 용출되어 급격한 용량감소로 인한 짧은 수명의 단점을 가지고 있다. 흔히 전구체로 쓰이는 $MnO_2$, $Mn_3O_4$, MnOOH등은 전기 분해법을 이용한 EMD가 주로 이용된다. 본 연구에서는 출발 물질로 $KMnO_4$와 $Mn(NO_3)_2$를 수용액 반응을 시켜서 농도, 온도변화에 따른 입자 형상 및 크기와 결정상의 변화를 관찰하고, 화학적 방법으로 얻어진 $MnO_2$와 LiOH를 합성하여 각각의 $LiMn_2O_4$를 비교 분석하고자한다.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.12 no.1
• /
• pp.27-30
• /
• 2002

ZnO co-doped Er:$LiNbO_3$ single crystal thin films have been grown on $LiNbO_3$ (001) substrate by liquid phase epitaxy (LPE) method. The melts of ZnO co-doped Er:$LiNbO_3$ was fixed $Er_2O_3$, concentration (1 mol%) and different ZnO concentrations 3 and 5 mol%. The crystallinity of ZnO co-doped Er :$LiNbO_3$ films became better than the $LiNbO_3$ substrate. At ZnO 5 mol% concentration, the surface of ZnO co-doped Er:$LiNbO_3$ film is affected by compressive stress along both the perpendicular and the parallel direction. Also the surface of ZnO 3 mol% co-doped Er:$LiNbO_3$film is smoother than the original $LiNbO_3$ substrate surface.

• Resources Recycling
• /
• v.10 no.6
• /
• pp.9-14
• /
• 2001

A sulfuric acid leaching of $LiCoO_2$as cathodic active materials of lithium ion secondary batteries was investigated in terms of reaction variables. In the absence of a reducing agent, the extraction of cobalt was less than 40% in 2 M sulfuric acid at $75^{\circ}C$ instead of that of lithium could be almost 100% in the same conditions. To improve the Co extraction, hydrogen peroxide was used as a reducing agent in the range 2~20 vol%. When over 10vo1% hydrogen peroxide was added, the extractions of both metals were improved to about 95%. It seems to be due to the reduction of Co(III) to Co(II) that can be readily dissolved. The extractions of Co and Li were increased with increasing $H_2$$SO_4$concentration and temperature, and amount of hydrogen peroxide and with decreasing of pulp density. The optimum leaching conditions were determined at $2 M H_2$$SO_4$concentration, $75^{\circ}C$ operating temperature, 100 g/L. initial pulp density, 20 vol% $H_2$$O_2$addition and 30 min.