이산화탄소 분리를 위한 씰린더형 전기화학적 막의 제조 및 분리 특성

정경열(Kyeong Youl Jung),박승빈(Seung Bin Park),양승만(Seung Man Yang) 한국화학공학회 1999 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.37 No.3

A cylindrical-shape electrochemical separation membrane was prepared using porous α-alumina. The electrodes were coated with NiO on both sides of the cylindrical-shape matrix by a dipping method. A mixture of Li₂CO₃/K₂CO₃(=62/ 38 molar ratio) was used as the electrolyte which was heated at 620 ℃ to be liquified and impregnated into the pores of the NiO-coated membrane. The prepared electrochemical membrane, which was operated at 620-650℃, was applied to the separation of CO₂ from a gas mixture(CO₂/O₂/N₂=0.25/0.16/0.59, molar ratio) and tested the effects of the current density on the permeability and concentration of carbon dioxide in the permeate, and the current efficiency. The permeability of carbon dioxide was increased monotonically with increasing the current density. The carbon dioxide was concentrated from 25% to 70% when increasing the current density. The current efficiency was decreased with increasing the current density. The prepared electrochemical membrane had the separation efficiency of 90.3%. In this work, it was proved that the cylindrical-shape electrochemical membrane prepared by using the porous inorganic membrane could be applied to the CO₂ separation from a gas mixture. However, the high overall resistance through the EMSD remains as a challenging problem.

분무열분해법에 의해 제조된(Ca, Sr)₂MgSi₂O₇:Eu²⁺ 형광체의 발광 특성

이호민,정경열,정하균,이종흔,Lee, Ho Min,Jung, Kyeong Youl,Jung, Ha-Kyun,Lee, Jong Heun 한국화학공학회 2006 Korean Chemical Engineering Research(HWAHAK KONGHA Vol. No.

분무열분해법을 이용하여$(Ca,Sr)_{2-y}MgSi_2O_7:Eu^{2+}{_y}$ 형광체 분말을 제조하고 $Eu^{2+}$의 농도, 후열처리온도 변화 및 Ca/Sr 비에 따른 발광특성을 조사하였다. 또한, Ca/Sr의 비를 변화시켜 발광특성의 변화를 관찰하였다. $Ca_2MgSi_2O_7$나 $Sr_2MgSi_2O_7$ 분말 모두 $1,000^{\circ}C$ 이상의 온도에서 열처리를 했을 때 순수한 정방정계 상이 제조되었다. $Ca_2MgSi_2O_7:Eu^{2+}{_y}$ 녹색 형광체는 $Eu^{2+}(y)$의 농도가 5 mol%, 후열처리 온도가 $1,250^{\circ}C$ 일 때 가장 높은 발광 강도는 보였다. ${(Ca_{1-x},Sr_x)}_{1.95}MgSi_2O_7:{Eu^{2+}}_{0.05}$의 발광 파장은 Sr의 농도가 증가함에 따른 결정장 감소로 인해 524nm에서 456nm로 점진적으로 blue shift 되었다. $Sr_2MgSi_2O_7:Eu^{2+}$는 Sr 자리에 약 10 mol% Ca를 치환시킴으로써 청색 형광체의 발광 강도는 크게 향상되었다. 제조된 분말들은 치밀하지 못하고 다공성 구조를 가져 후열처리 전에는 구형을 유지하였으나 열처리($900{\sim}1,300^{\circ}C$) 후에는 구형의 형상을 잃고 입자들 간의 응집이 발생하였다. $(Ca,Sr)_{2-y}MgSi_2O_7:Eu^{2+}{_y}$ (CMS) phosphor particles were prepared by using a spray pyrolysis process. The luminescent property was optimized by changing the content of Eu and the post-treatment temperature. The luminescence characteristics were also monitored with changing the ratio of Ca to Sr. The pure tetragonal $Ca_2MgSi_2O_7$ or $Sr_2MgSi_2O_7$ particles were obtained when the post-treatment temperature was over $1,000^{\circ}C$. The highest emission intensity of CMS particles were achieved when the concentration (y) of Eu and the treatment temperature were 0.05 and $1,250^{\circ}C$,respectively. The emission wavelength $({\lambda}_{max})$ of ${(Ca_{1-x},Sr_x)}_{1.95}MgSi_2O_7:{Eu^{2+}}_{0.05}$ was gradually shifted from 524 nm to 456 nm with increasing the content of Sr due to the reduction of crystal field strength. The emission intensity and its width of $Sr_2MgSi_2O_7:Eu$ was greatly enhanced by substituting Ca of less than 10 mol% for Sr without any significant peak shift. The morphology of as-prepared particles was spherical, but changed to irregular-shaped one after the post treatment at the temperature range from 900 at $1,300^{\circ}C$.

분무열분해법으로 제조된 SrAl2O4:Ho3+ 녹색 형광체의 발광특성

정경열 ( Kyeong Youl Jung ),김우현 ( Woo Hyun Kim ) 한국화학공학회 2015 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.53 No.5

Ho3+ doped SrAl2O4 upconversion phosphor powders were synthesized by spray pyrolysis, and the crystallographicproperties and luminescence characteristics were examined by varying activator concentrations and heattreatment temperatures. The effect of organic additives on the crystal structure and luminescent properties was also investigated. SrAl2O4:Ho3+ powders showed intensive green emission due to the 5F4/5S2 → 5I8 transition of Ho3+. The optimal Ho3+ concentration in order to achieve the highest luminescence was 0.1%. Over this concentration, emission intensities were largely diminished via a concentration quenching due to dipole-dipole interaction between activator ions.According to the dependence of emission intensity on the pumping power of a laser diode, it was clear that the upconversion of SrAl2O4:Ho3+ occurred via the ground state absorption-excited state absorption processes involving two near-IR photons. Synthesized powders were monoclinic as a major phase, having some hexagonal phase. The increase of heat-treatment temperatures from 1000 °C to 1350 °C led to crystallinity enhancement of monoclinic phase, reducing hexagonal phase. The hexagonal phase, however, did not disappear even at 1350 °C. When both citric acid (CA) and ethylene glycol (EG) were added to the spray solution, the resulting powders had pure monoclinic phase without forming hexagonal phase, and led to largely enhancement of crystallinity. Also, N,N-Dimethylformamide (DMF) addition to the spray solution containing both CA and EG made it possible to effectively reduce the surface area of SrAl2O4:Ho3+ powders. Consequently, the SrAl2O4:Ho3+ powders prepared by using the spray solution containing CA/EG/DMF mixture as the organic additives showed about 168% improved luminescence compared to the phosphor prepared without organic additives. It was concluded that both the increased crystallinity of high-purity monoclinic phase and the decrease of surface area were attributed to the large enhancement of upconversion luminescence.

분무열분해법으로 CeO2:Er/Yb 형광체 제조 및 발광특성 최적화

정경열 ( Kyeong Youl Jung ),박재훈 ( Jea Hoon Park ),송신애 ( Shin Ae Song ) 한국공업화학회 2015 공업화학 Vol.26 No.3

Submicron-sized CeO2:Er3+/Yb3+ upconversion phosphor particles were synthesized by spray pyrolysis, and their luminescent properties were characterized by changing the concentration of Er3+ and Yb3+. CeO2:Er3+/Yb3+ showed an intense green and red emission due to the 4S3/2 or 2H11/2 → 4I15/2 and 4F9/2 → 4I15/2 transition of Er3+ ions, respectively. In terms of the emission intensity, the optimal concentrations of Er and Yb were 1.0 % and 2.0%, respectively, and the concentration quenching was found to occur via the dipole-dipole interaction. Upconversion mechanism was discussed by using the dependency of emission intensities on pumping powers and considering the dominant depletion processes of intermediate energy levels for the red and green emission with changing the Er3+ concentration. An energy transfer from Yb3+ to Er3+ in CeO2 host was mainly involved in ground-state absorption (GSA), and non-radiative relaxation from 4I11/2 to 4I13/2 of Er3+ was accelerated by the Yb3+ co-doping. As a result, the Yb3+ co-doping led to greatly enhance the upconversion intensity with increasing ratios of the red to green emission. Finally, it is revealed that the upconversion emission is achieved by two photon processes in which the linear decay dominates the depletion of intermediate energy levels for green and red emissions for CeO2:Er3+/Yb3+ phosphor.

Preparation and Luminescence Optimization of CeO₂:Er/Yb Phosphor Prepared by Spray Pyrolysis

정경열,박재훈,송신애,Jung, Kyeong Youl,Park, Jea Hoon,Song, Shin Ae The Korean Society of Industrial and Engineering C 2015 공업화학 Vol.26 No.3

분무열분해법을 이용하여 서브 미크론 크기의 $CeO_2:Er^{3+}/Yb^{3+}$ 상향 변환 형광체 입자를 합성하고 $Er^{3+}$ 및 $Yb^{3+}$ 농도 변화에 따른 발광특성을 조사하였다. 합성한 $CeO_2:Er^{3+}/Yb^{3+}$는 $Er^{3+}$ 활성이온의 $^4S_{3/2}/^2H_{11/2}{\rightarrow}^4I_{15/2}$ 및 $^4F_{9/2}{\rightarrow}^4I_{15/2}$ 전이에 기인한 강한 녹색 및 적색 발광을 보였다. 가장 높은 발광을 보이는 활성제 농도는 Er = 1.0% 그리고 Yb = 2.0%이며, 농도소광 현상은 쌍극자-쌍극자 상호작용을 통해 일어남이 확인되었다. 레이저 다이오드 여기 광 세기에 대한 발광강도 의존성을 활성이온 농도에 따라 조사하였고, 발광 중간 에너지 레벨의 주 소멸과정을 고려하여 발광 메커니즘을 조사하였다. $Yb^{3+}$에서 $Er^{3+}$으로 에너지 전달은 바닥 상태 흡수(ground state absorption, GSA)에 기여하고, $Yb^{3+}$ 도핑은 $^4I_{11/2}{\rightarrow}^4I_{13/2}$ 전이를 가속화시켜 적색/녹색 발광세기 비를 상승시킨다. 최종적으로 분무열분해법으로 제조된 $CeO_2:Er^{3+}/Yb^{3+}$ 형광체의 발광은 선형 감쇠가 중간 에너지 레벨의 고갈을 지배하는 2 광자 프로세스에 의해 일어남을 확인하였다. Submicron-sized $CeO_2:Er^{3+}/Yb^{3+}$ upconversion phosphor particles were synthesized by spray pyrolysis, and their luminescent properties were characterized by changing the concentration of $Er^{3+}$ and $Yb^{3+}$. $CeO_2:Er^{3+}/Yb^{3+}$ showed an intense green and red emission due to the $^4S_{3/2}$ or $^2H_{11/2}{\rightarrow}^4I_{15/2}$ and $^4F_{9/2}{\rightarrow}^4I_{15/2}$ transition of $Er^{3+}$ ions, respectively. In terms of the emission intensity, the optimal concentrations of Er and Yb were 1.0 % and 2.0%, respectively, and the concentration quenching was found to occur via the dipole-dipole interaction. Upconversion mechanism was discussed by using the dependency of emission intensities on pumping powers and considering the dominant depletion processes of intermediate energy levels for the red and green emission with changing the $Er^{3+}$ concentration. An energy transfer from $Yb^{3+}$ to $Er^{3+}$ in $CeO_2$ host was mainly involved in ground-state absorption (GSA), and non-radiative relaxation from $^4I_{11/2}$ to $^4I_{13/2}$ of $Er^{3+}$ was accelerated by the $Yb^{3+}$ co-doping. As a result, the $Yb^{3+}$ co-doping led to greatly enhance the upconversion intensity with increasing ratios of the red to green emission. Finally, it is revealed that the upconversion emission is achieved by two photon processes in which the linear decay dominates the depletion of intermediate energy levels for green and red emissions for $CeO_2:Er^{3+}/Yb^{3+}$ phosphor.

분무열분해법을 이용하여 M₃MgSi₂O₈:Eu²⁺ (M=Ca, Sr, Ba) 형광체 분말의 VUV 특성 최적화

정유리,정경열,Jung, You-Ri,Jung, Kyeong-Youl 한국분말야금학회 2008 한국분말재료학회지 (KPMI) Vol.15 No.5

Spray pyrolysis was applied to prepare $M_{3}MgSi_{2}O_{8}:Eu^{2+}$ (M=Ca, Sr, Ba) blue phosphor powder. The library of a Ca-Sr-Ba ternary system was obtained by a combinatorial method combined with the spray pyrolysis in order to optimize the luminescent property under vacuum ultraviolet (VUV) excitation. 10 potential compositions were chosen from the first screening. The emission shifted to longer wavelength as Ca became a dominant element and the emission intensity was greatly reduced in the composition region at which Ba is dominant element. On the base of the first screening result, the second fine tuning was carried out in order to optimize the luminescence intensity under VUV excitation. The optimal composition for the highest luminescence intensity was $(Ca_{1.7},\;Sr_{0.3},\;Ba_{1.0})Si_{2}O_{8}:Eu^{2+}$ which had the color coordinate of (0.152, 0.072) and about 64% emission intensity of $BaMgAl_{10}O_{17}$ (BAM) phosphor.

다단계구조 개선에 의해 제조된 무기막을 이용한 혼합가스로 부터 수소분리

정경열,소재현,박승빈,양승만 ( Kyeong Youl Jung,Jae Hyun So,Seung Bin Park,Seung Man Yang ) 한국화학공학회 1996 화학공학의이론과응용 Vol.2 No.2

나노미터 크기의 ZnO 입자를 이용한 trichloroethylene 의 광분해반응

정경열 (학),강윤찬 (학),박승빈 (정) ( Kyeong Youl Jung,Yun Chan Kang,Seung Bin Park ) 한국화학공학회 1995 화학공학의이론과응용 Vol.1 No.2

분무열분해법으로 YAG:Ce 제조시 용액 조건이 발광특성에 미치는 영향

이유미,강태원,정경열,Lee, You-Mi,Kang, Tae-Won,Jung, Kyeong-Youl 한국분말야금학회 2012 한국분말재료학회지 (KPMI) Vol.19 No.3

YAG:Ce yellow phosphor particles were synthesized by spray pyrolysis with changing the solution properties and their luminous properties, crystal structure, and morphological changes were studied by using PL measurement, XRD, and SEM analysis. It was clear that the solution properties significantly affected the crystal phase, crystallite size, the PL intensity, and the morphology of YAG:Ce particles. At low calcination temperature, the addition of urea only to the spray solution was helpful to form a pure YAG phase without any impurity phases, as the result, the highest luminescence intensity was achieved at the calcination temperature of $900^{\circ}C$. When the calcination temperatures were larger than $1300^{\circ}C$, however, the YAG particles prepared without any additive showed the highest luminescent intensity. Regardless of the solution conditions, the emission intensity of YAG:Ce particles prepared by spray pyrolysis showed a linear relation with the crystallite size. In terms of the morphology of YAG:Ce particles, the addition of both DCCA and $NH_4OH$ to the spray solution was effective to prepare a spherical and dense structured YAG particles.

팔라듐 함침 무기막에 의한 혼합가스로부터 수소분리

정경열,윤건영,박승빈,양승만 ( Kyeong Youl Jung,Keon Yeong Yoon,Seong Bin Park ) 한국화학공학회 1996 화학공학의이론과응용 Vol.2 No.1