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Structural,Sintering and Electrical Properties of Cr-doped La_(0.6)Sr_(0.4)Cr_xFe_(1-x)O_(3-δ)(x=0.10,0.20) Oxides

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Journal of Materials Science & Technology 2012年第7期28卷 654-660页

作者： LinlinZhu Jong Pyo Kim Sou Hwan Son jung hoon Park State Key SLaboratory of Catalysis.Dalian Institute of Chemical Physics Chinese~Academy of Sciences Dalian 116023 China Greenhouse Gas Research Center Climate Change Technology Research Division Korea Institute of Energy ResearchDaejeon 305-343 Korea College of Chemistry and Materials Science Liaoning University of Petroleum and Chemical Technology Fushun113001 China

The perovskite Cr-doped La0.6Sr0.4CrxFe1-xO3-δ （x=0.10, 0.20） oxides were synthesized via the citrate gel method. The perovskite forming of the Lao.6Sr0.4CrxFel-xO3-δ （x=0.10, 0.20） oxides were studied by ther- mogravimetric analysis （TG）, differential scanning calorimetry （DSC）, and X-ray diffraction （XRD）. Structural and chemical stability under H2-containing helium atmospheres of Lao.6Sro.4CrxFel-xO3-δ （x=0.10, 0.20） were investigated by TG and XRD. The sintering microstructures of the perovskite Lao.6Sr0.4Cr2Fel-xO3-δ （x--0.10, 0.20） ceramics were investigated by scanning electron microscopy （SEM）, and the electrical conduc- tivities of both oxide ceramics were also measured up to 900℃. The results demonstrated that the chemical stability of the Co-free ***.4CrxFe1-xO3-δ （x=0.10, 0.20） oxides was significantly improved compared to the Co-containing Lao.6Sr0.4C00.2Fe0.8O3-δ and Ba0.5Sr0.5Co0.8Fe0.2O3-δ oxides. The incorporation of Cr cations in the B-site of the pervoskite oxides resulted in the improved structural and chemical stability of the as-synthesized Lao.6Sr0.4CrxFe1-xO3-δ （x=0.10, 0.20） oxides.

关键词： Perovskite Crystal structure Sintering Electrical conductivity

The Effect of Fabrication Conditions for GDC Buffer Layer on Electrochemical Performance of Solid Oxide Fuel Cells

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Nano-Micro Letters 2013年第3期5卷 151-158页

作者： jung-hoon Song Myung Geun jung Hye Won Park Hyung-Tae Lim Fuel Cell Project Research Institute of Industrial Science and Technology (RIST) School of Nano & Advanced Materials Engineering Changwon National University

A Gd-doped ceria（GDC） buffer layer is required between a conventional yttria-stabilized zirconia（YSZ） electrolyte and a La-Sr-Co-Fe-O3（LSCF） cathode to prevent their chemical reaction. In this study,the effect of varying the conditions for fabricating the GDC buffer layer, such as sintering temperature and amount of sintering aid, on the solid oxide fuel cell（SOFC） performance was investigated. A finer GDC powder（i.e., ultra-high surface area）, a higher sintering temperature（1290℃）, and a larger amount of sintering aid（12%） resulted in improved densification of the buffer layer; however, the electrochemical performance of an anode-supported cell containing this GDC buffer layer was poor. These conflicting results are attributed to the formation of（Zr, Ce）O2 and/or excess cobalt grain boundaries（GBs） at higher sintering temperatures with a large amount of sintering aid（i.e., cobalt oxide）. A cell comprising of a cobalt-free GDC buffer layer, which was fabricated using a low-temperature process, had lower cell resistance and higher stability. The results indicate that electrochemical performance and stability of SOFCs strongly depend on fabrication conditions for the GDC buffer layer.

关键词： Solid oxide fuel cell(SOFC) Gd-doped ceria Sintering aid Sol-gel spin coating

Synergistic passivation of MAPbI_(3) perovskite solar cells by compositional engineering using acetamidinium bromide additives

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Journal of Energy Chemistry 2021年第8期30卷 755-762,I0016页

作者： Kyungeun jung Weon-Sik chae Jae Won Choi Ki Chul Kim Man-Jong Lee Department of Chemistry Konkuk University143-701 SeoulSouth Korea Department of Advanced Technology Fusion Konkuk University143-701 SeoulSouth Korea Analysis Research Division Daegu CenterKorea Basic Science Institute702-701 DaeguSouth Korea Division of Chemical Engineering Konkuk University05029 SeoulSouth Korea

For the global commercialization of highly efficient and stable perovskite solar cells(PSCs),it is necessary to effectively suppress the formation of various defects acting as nonradiative recombination sources in perovskite light-harvesting *** defects between the charge-selective layer and the perovskite are easily formed in the solution process used to fabricate perovskite *** addition,owing to the difference in thermal expansion coefficients between the substrate and the perovskite film,internal residual tensile stress inevitably occurs,resulting in increased nonradiative ***,a simple compositional engineering scheme for realizing efficient and stable PSCs,which incorporates acetamidinium bromide(AABr)as an additive into the MAPbI_(3) lattice,is *** an additive,AABr has been found to provide synergistic multiple passivation for both internal and interfacial *** was found to effectively release the tensile strain of the MAPbI_(3) film by forming a structure stabilized by NH-I hydrogen bonds,as evidenced by calculations based on density functional theory(DFT).Furthermore,the incorporated AABr additives created a charge carrier recombination barrier to enhance charge collection capability by reducing interfacial ***,a power conversion efficiency(PCE)of 20.18%was achieved using a planar device employing AABr-incorporated MAPbI_(3).This was substantially higher than the 18.32% PCE of a pristine MAPbI_(3)-based ***,unencapsulated PSCs using AABr-incorporated MAPbI_(3) absorbers exhibited excellent long-term stability,maintaining>95% of initial PCE up to 1200 hours in ambient air.

关键词： Acetamidinium bromide Planar perovskite solar cell Tensile stress Interface passivation Recombination barrier

Occurrence and distribution of hydroxylated isoprenoid glycerol dialkyl glycerol tetraethers(OH-GDGTs) in the Han River system, South Korea

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Acta Geochimica 2017年第3期36卷 367-369页

作者： Sujin Kang Kyoung-hoon Shin jung-Hyun Kim Department of Marine Science and Convergence Technology Hanyang University Ansan Korea Korea Polar Research Institute 26 Songdomirae-ro Yeonsugu Incheon Korea

We investigated the occurrence and distribution of terrestrial-derived hydroxylated isoprenoid glycerol dialkyl glycerol tetraethers(OH-GDGTs) in the Han River system and their potential impact on the application of the ring index of OH-GDGTs(RI-OH) as a sea surface temperature(SST) proxy in the eastern Yellow Sea. Thereby, we analyzed various samples collected along the Han River and from its surrounding areas(South Korea, n = 34). The OHGDGTs were found in all samples investigated. OH-GDGT-0 was the dominant OH-GDGT component in the estuary and marine samples while OH-GDGT-2 was generally dominant in the soils, the lake sediments and the river suspended particulate matter(SPM). Our results thus suggests a possible warm bias of the RI-OH-derived summer SSTs in the coastal zone to which a large amount of terrestrial organic matter is being supplied. Further studies are necessary to better assess the applicability of the RI-OH proxy in the eastern Yellow Sea.

关键词： Hydroxylated isoprenoid glycerol dialkyl glycerol tetraethers(OH-GDGTs) Sea surface temperature(SST) Han river Yellow Sea

pH-induced structural changes of surface immobilized poly (L-lysine) by two-dimensional (2D) infrared correlation study

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Chinese Chemical Letters 2015年第2期26卷 173-176页

作者： Eun Joo Yoo Boknam chae Young Mee jung Seung Woo Lee School of Chemical Engineering Yeungnam University Pohang Accelerator Laboratory Department of Chemistry Kangwon National University

This paper reports the pH-induced structural changes in the surface immobilized poly（L-lysine）（PLL）***-dimensional（2D） correlation analysis was applied to the Fourier transform infrared（FTIR）spectra of the surface-immobilized PLL film to examine the spectral changes induced by the alternations of the protonation state of the amino group in the side *** spectral changes in the FTIR spectra of the PLL film were observed between pH 7 and *** decrease in the protonation state of the amino group in the side chain induced spectral changes in the amino group as well as conformational changes in the alky]group in the side *** pH 1-8,the spectral changes in the amino and alkyl groups in the side chain occurred before those of the amide group in the main chain of the surface immobilized PLL film.

关键词： Poly(L-lysine)(PLL) Surface-immobilized polypeptide FT-IR spectroscopy 2D correlation spectroscopy

Microfluidic dual loops reactor for conducting a multistep reaction

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Frontiers of Chemical Science and Engineering 2018年第2期12卷 239-246页

作者： Si Hyung Jin Jae-hoon jung Seong-Geun Jeong Jongmin Kim Tae jung Park Chang-Soo Lee Department of Chemical Engineering Chungnam National University Daejeon 34134 Korea Lotte Chemical R&D Center Daejeon 34110 Korea Department of Chemistry Chung-Ang University Seoul 06974 Korea

Precise control of each individual reaction that constitutes a multistep reaction must be performed to obtain the desired reaction product efficiently. In this work, we present a microfluidic dual loops reactor that enables multistep reaction by integrating two identical loop reactors. Specifically, reactants A and B are synthesized in the first loop reactor and transferred to the second loop reactor to synthesize with reactant C to form the final product. These individual reactions have nano-liter volumes and are carded out in a stepwise manner in each reactor without any cross-contamination issue. To pre- cisely control the mixing efficiency in each loop reactor, we investigate the operating pressure and the operating frequency on the mixing valves for rotary mixing. This microfluidic dual loops reactor is integrated with several valves to realize the fully automated unit operation of a multistep reaction, such as metering the reactants, rotary mixing, transportation, and collecting the product. For proof of concept, CdSeZn nanopartieles are successfully synthesized in a microfluidic dual loops reactor through a fully automated mukistep reaction. Taking all of these features together, this microfluidic dual loops reactor is a general microfluidic screening platform that can synthesize various materials through a multistep reaction.

关键词： microfluidics multistep reaction rotary mixing nanoparticle

Electrochemically metal-doped reduced graphene oxide films:Properties and applications

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Journal of Materials Science & Technology 2020年第5期40卷 72-80页

作者： Myung-Sic chae Tae Ho Lee Kyung Rock Son Tae hoon Park Kyo Seon Hwang Tae Geun Kim School of Electrical Engineering Korea UniversityAnam-ro 145Seongbuk-guSeoul 02841South Korea Department of Clinical Pharmacology and Therapeutics College of MedicineKyung Hee UniversitySeoul 02447South Korea

The fine control of doping levels in graphene materials such as reduced graphene oxide(RGO)is important to properly manipulate their ambipolar transport characteristics for various device ***,conventional doping methods involve complex chemical reactions,large-scale doping processes,and poor ***,a simple and controllable electrochemical doping treatment(EDT),performed via the conductive channels created at the RGO surface by the application of an electric field,is introduced to tailor the electrical properties of RGO films.X-ray photoelectron spectroscopy and Raman spectroscopy measurements are performed to detect the presence of Ni atoms in RGO films after the EDT(EDT-RGO).Then,EDT-RGO field-effect transistors(FETs)are fabricated with different doping areas(0 to 100%fractional area)on the RGO active channel to investigate the effect and selective-area doping capability of the *** to p-type doping compensation by the intercalated Ni atoms,the electron mobility of the EDT-RGO FET decreases from 1.40 to 0.12 cm2 V-1s-1 compared with that of the undoped RGO-FET,leading to the conversion from ambipolar to unipolar p-type transfer characteristics.

关键词： Reduced graphene oxide Electrochemical doping treatment Electrical breakdown process Field-effect transistor

Rescue endoscopic band ligation of iatrogenic gastric perforations following failed endoclip closure

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World Journal of Gastroenterology 2013年第6期19卷 955-959页

作者： Joung-Ho Han Tae hoon Lee Yunho jung Suck-Ho Lee Hyun Kim Hye-Suk Han Heebok chae Seon Mee Park Seijin Youn Division of Gastroenterology Department of Internal medicineChungbuk National University College of MedicineCheongju 361-711South Korea Division of Gastroenterology Department of Internal MedicineSoon Chun Hyang University College of MedicineCheonan HospitalCheonan 330-721South Korea

Iatrogenic gastric perforation is one of the most serious complications during therapeutic endoscopy,despite significant advances in endoscopic techniques and *** case study evaluated the clinical efficacy and safety of the rescue endoscopic band ligation (EBL) technique in iatrogenic gastric wall perforation following the failure of primary endoclip *** patients were enrolled in this *** patients underwent emergency endoscopy following the onset of acute gastric wall perforation during endoscopic *** outcome measurements were primary technical success and immediate or delayed procedure-related *** endoscopic closure using band ligation was reported in all patients,with no complication *** conclude that EBL may be a feasible and safe alternate technique for the management of acute gastric perforation,especially in cases where closure is difficult with endoclips.

关键词： Gastric perforation Endoscopy Band ligation

Effect of precursor thermal history on the formation of amorphous and crystalline calcium carbonate

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Particuology 2017年第4期15卷 29-34页

作者： Jitendra Pal Singh Mi-jung Ji Cheol-Hwee Shim Sang Ok Kim Keun Hwa chae Advanced Analysis Center Korea Institute of Science and Technology Seou102792 Republic of Korea Department of Biomedical Engineering Seonam University Namwon 55724 Republic of Korea

The role of the thermal history of the precursor was studied for amorphous and crystalline calcium carbon- ate phases synthesized from calcium nitrate. The X-ray diffraction patterns of these phases are influenced by their annealing temperature of 0, 300, 400, and 500 ℃. However, the effect of the precursor thermal history on the X-ray diffraction pattern of the resulting calcium carbonate phase is negligible. Transmis- sion electron microscopy indicates that materials annealed at 400 ℃ consist of amorphous aggregates, irrespective of the precursor thermal history. The crystallite size of crystalline calcium carbonate is influ- enced by the precursor thermal history, and ranges from 23 to 26 rim. Near-edge X-ray absorption fine structure measurements indicate that the annealing temperature plays an important role in determining the local electronic structure. The role of the thermal history of the precursor is also important for the resultinu electronic structure.

关键词： Amorphous material Particles Electron microscopy X-ray techniques NEXAFS Calcium carbonate