논문 상세보기

대한금속재료학회(구 대한금속학회)> 대한금속재료학회지> A-site 조성 제어를 통한 FA기반 페로브스카이트의 상안정화 및 전단 코팅 최적화 연구

KCI등재SCISCOUPUS

A-site 조성 제어를 통한 FA기반 페로브스카이트의 상안정화 및 전단 코팅 최적화 연구

Study on A-Site Compositional Mixing for the Shear Coating Process of FA-Based Lead Halide Perovskites

김한솔 ( Hansol Kim ) , 구혜원 ( Hyewon Gu ) , 송민주 ( Minju Song ) , 정중희 ( Choong-heui Chung ) , 오용준 ( Yong-jun Oh ) , 송창은 ( Chang Eun Song ) , 홍기하 ( Ki-ha Hong )
  • : 대한금속재료학회
  • : 대한금속재료학회지 59권5호
  • : 연속간행물
  • : 2021년 04월
  • : 321-328(8pages)
대한금속재료학회지

DOI


목차

1. 서 론
2. 실험 방법
3. 결과 및 고찰
4. 결 론
Acknowledgement
REFERENCES

키워드 보기


초록 보기

Halide perovskite solar cells have been attracting tremendous attention as next-generation solar cell materials because of their excellent optical and electrical properties. Formamidinium lead tri-iodide (FAPbI3) exhibits the narrowest band gap among lead iodide perovskites and shows excellent thermal and chemical stability, also. However, the large-area coating of FAPbI3 needed for commercialization has not been successful because of the instability of the black phase of FAPbI3 at ambient temperature. This study presents a compositional engineering direction to control the polymorph of the FAPbI3 thin film for the shear coating processes, without halide mixing. By adopting a hot substrate above 100 ℃, our shear coating process can produce the black phase FA-based halide perovskites without halide mixing. We carefully investigate the Cs- FA and MA-FA mixed lead iodide perovskites’ phase stability by combining the study with thin-film fabrication and ab initio calculations. Cs-FA mixing shows promising behaviors for stabilizing α-FAPbI3 (black phase) compared with MA-FA. Stable FA-rich perovskite films cannot be achieved via shear coating processes with MA-FA mixing. Ab initio calculations revealed that Cs-FA mixing is excellent for inhibiting phase decomposition and water incorporation. This study is the first report that FA-based halide perovskite thin films can be made with the shear coating process without MA-Br mixing. We reveal the origin of the stable film formation with Cs-FA mixing, and present future research directions for fabricating FA-based perovskite thin films using shear coating.
(Received January 14, 2021; Accepted March 4, 2021)

UCI(KEPA)

간행물정보

  • : 공학분야  > 금속공학
  • : KCI등재
  • : SCI,SCOPUS
  • : 월간
  • : 1738-8228
  • : 2288-8241
  • : 학술지
  • : 연속간행물
  • : 1963-2021
  • : 6952


저작권 안내

한국학술정보㈜의 모든 학술 자료는 각 학회 및 기관과 저작권 계약을 통해 제공하고 있습니다.

이에 본 자료를 상업적 이용, 무단 배포 등 불법적으로 이용할 시에는 저작권법 및 관계법령에 따른 책임을 질 수 있습니다.

59권10호(2021년 10월) 수록논문
최근 권호 논문
| | | |

KCI등재 SCI SCOPUS

1저온 템퍼링을 이용한 1.2 GPa급 페라이트계 경량철강 개발

저자 : 배효주 ( Hyo Ju Bae ) , 고광규 ( Kwang Kyu Ko ) , 박형석 ( Hyoung Seok Park ) , 정재석 ( Jae Seok Jeong ) , 김정기 ( Jung Gi Kim ) , 성효경 ( Hyokyung Sung ) , 설재복 ( Jae Bok Seol )

발행기관 : 대한금속재료학회 간행물 : 대한금속재료학회지 59권 10호 발행 연도 : 2021 페이지 : pp. 683-691 (9 pages)

다운로드

(기관인증 필요)

초록보기

Previously reported low-Mn ferritic-based lightweight steels are potential candidates for industrial applications, however, they typically exhibit lower strength, with < 1 GPa and lower strength-ductility balance, than medium- and high-Mn austenitic lightweight steels. Herein, we introduce a low-temperature tempering-induced partitioning (LTP) treatment that avoids the strength-ductility dilemma of low-Mn ferritic-based steels. When the LTP process was performed at 330 ℃ for 665 s, the strength of typical ferritic base Fe-2.8Mn5.7Al0.3C (wt%) steel with heterogeneously sized metastable austenite grains embedded in a ferrite matrix, exceeded 1.1 GPa. Notably, the increased strength-ductility balance of the LTP-processed ferritic steel was comparable to that of the high-Mn based austenitic lightweight steel series. Using microscale to nearatomic scale characterization we found that the simultaneous improvement in strength and total elongation could be attributed to size-dependent dislocation movement, and controlled deformation-induced martensitic transformation.
(Received May 14 2021; Accepted July 5, 2021)

KCI등재 SCI SCOPUS

2나노구조의 ZrB2-Al2O3 복합재료 합성과 소결

저자 : 손인진 ( In-jin Shon )

발행기관 : 대한금속재료학회 간행물 : 대한금속재료학회지 59권 10호 발행 연도 : 2021 페이지 : pp. 692-697 (6 pages)

다운로드

(기관인증 필요)

초록보기

ZrB2 is considered a candidate material for ultra-high temperature ceramics because of its high thermal conductivity, high melting point, and low coefficient of thermal expansion. Despite these attractive properties, ZrB2 applications are limited by its low fracture toughness below the brittle-ductile transition temperature. To improve its ductile properties, the approach universally utilized has been to add a second material to form composites, and to fabricate nanostructured materials. In this study a dense nanostructured ZrB2-Al2O3 composite was rapidly sintered using the pulsed current activated heating (PCAH) method within 3 min in one step, from mechanically synthesized powders of ZrB2 and Al2O3. Consolidation was accomplished using an effective combination of current and mechanical pressure. A highly dense ZrB2- Al2O3 composite with a relative density of up to 97.4% was fabricated using the simultaneous application of 70 MPa pressure and a pulsed current. The fracture toughness and hardness of the ZrB2-Al2O3 composite were 3.9 MPa.m1/2 and 1917 kg/㎟, respectively. The fracture toughness of the composite was higher than that of monolithic ZrB2.
(Received May 7 2021; Accepted July 20, 2021)

KCI등재 SCI SCOPUS

3ERNiFeCr-2 용가재 적용에 따른 CM247LC 초내열합금 용접부 응고균열 민감도 변화 거동

저자 : 김경민 ( Kyeong-min Kim ) , 정혜은 ( Hye-eun Jeong ) , 정예선 ( Ye-seon Jeong ) , 이의종 ( Uijong Lee ) , 이형수 ( Hyungsoo Lee ) , 서성문 ( Seong-moon Seo ) , 천은준 ( Eun-joon Chun )

발행기관 : 대한금속재료학회 간행물 : 대한금속재료학회지 59권 10호 발행 연도 : 2021 페이지 : pp. 698-708 (11 pages)

다운로드

(기관인증 필요)

초록보기

The metallurgical aspects of weld solidification cracking in Ni-based superalloys (with Ti+Al > 5 mass%) have not been widely investigated thus far. Herein, the solidification cracking susceptibility of the CM247LC superalloy and its welds with ERNiFeCr-2 filler wire was quantitatively evaluated using a novel modified Varestraint testing method, for the successful manufacturing of CM247LC superalloy gas turbine blades. It was found that the solidification brittle temperature range (BTR) of the CM247LC superalloy was 400 K. This measurement was obtained with a high-speed thermo-vision camera. The BTR increased to 486 K for the CM247LC/ERNiFeCr-2 welds (dilution ratio: 74%). Theoretical calculations (i.e., the Scheil equation, performed using Thermo-Calc software) were conducted to determine the temperature range in which both solid and liquid phases coexist, together with the microstructural characterization of the solidification cracking surfaces. The greater increase in BTR for the CM247LC/ERNiFeCr-2 welds than that for CM247LC was attributed to the enlargement of the solid-liquid coexistence temperature range. This correlated with the formation of a low-temperature Laves phase during the terminal stage of solidification, and was affected by the diluted Nb and Fe components in the ERNiFeCr-2 filler metal. Based on the experimental and theoretical results, the proposed modified Varestraint testing method for dissimilar welds is expected to be an effective testing process for solidification cracking behavior in the manufacturing of high-soundness CM247LC superalloy welds.
(Received June 24 2021; Accepted July 16, 2021)

KCI등재 SCI SCOPUS

4수소 분위기에서 Mg와 VCl3의 밀링에 의한 Mg의 수소 흡수 방출 특성의 향상

저자 : 송명엽 ( Myoung Youp Song ) , 이성호 ( Seong Ho Lee ) , 곽영준 ( Young Jun Kwak )

발행기관 : 대한금속재료학회 간행물 : 대한금속재료학회지 59권 10호 발행 연도 : 2021 페이지 : pp. 709-717 (9 pages)

다운로드

(기관인증 필요)

초록보기

VCl3 (vanadium (III) chloride) was selected as an additive to Mg to increase the hydrogenation and dehydrogenation rates and the hydrogen storage capacity of Mg. Instead of MgH2, Mg was used as a starting material since Mg is cheaper than MgH2. Samples with a composition of 95 wt% Mg + 5 wt% VCl3 (named Mg-5VCl3) were prepared by milling in hydrogen atmosphere (reactive milling). In the first cycle (n=1), Mg-5VCl3 absorbed 5.38 wt% H for 5 min and 5.95 wt% H for 60 min at 573 K in 12 bar hydrogen. The activation of Mg-5VCl3 was completed after three hydrogenation-dehydrogenation cycles. During milling in hydrogen, β-MgH2 and γ-MgH2 were produced. The formed β-MgH2 and γ-MgH2 are considered to have made the effects of reactive milling stronger as β-MgH2 and γ-MgH2 themselves were being pulverized. The introduced defects and the interfaces between the Mg and the phases formed during the reactive milling and during hydrogenation-dehydrogenation cycling are believed to serve as heterogeneous active nucleation sites for MgH2 and Mg-H solid solution. The phases generated during hydrogenation-dehydrognation cycling are also believed to prevent the particles from coalescing during hydrogenation-dehydrognation cycling.
(Received June 13 2021; Accepted July 28, 2021)

KCI등재 SCI SCOPUS

5RF sputtering으로 증착된 ZnO 박막을 전자 수송층으로 사용한 양자점 발광 다이오드에 관한 연구

저자 : 강명석 ( Myoungsuk Kang ) , 김지완 ( Jiwan Kim )

발행기관 : 대한금속재료학회 간행물 : 대한금속재료학회지 59권 10호 발행 연도 : 2021 페이지 : pp. 718-723 (6 pages)

다운로드

(기관인증 필요)

초록보기

We report a highly efficient quantum dot light emitting diode (QLEDs) with a radio frequency (RF) sputtered ZnO thin film as an electron transport layer (ETL) instead of the conventional ZnO nanoparticles (NPs) by solution process. ZnO NPs have been used as a key material to improve the performance of QLEDs, but the charge imbalance in ZnO NPs resulting from fast electron injection, and their limited uniformity are significant disadvantages. In this study, ZnO layers were deposited by RF sputtering with various O2 partial pressures. All of the ZnO films showed preferential growth along the (002) direction, smooth morphology, and good optical transmittance. To test their feasibility for QLEDs, we fabricated devices with RF sputtered ZnO layers as an ETL, which has the inverted structure of ITO/RF sputtered ZnO/QDs/CBP/MoO3/Al. The optical/electrical characteristics of two devices, comprised of RF sputtered ZnO and ZnO NPs, were compared with each other. QLEDs with the sputtered ZnO ETL achieved a current efficiency of 11.32 cd/A, which was higher than the 8.23 cd/A of the QLEDs with ZnO NPs ETL. Next, to find the optimum ZnO thin film for highly efficient QLEDs, deposition conditions with various O2 partial pressures were tested, and device performance was investigated. The maximum current efficiency was 13.33 cd/A when the ratio of Ar/O2 was 4:3. Additional oxygen gas reduced the O vacancies in the ZnO thin film, which resulted in a decrease in electrical conductivity, thereby improving charge balance in the emission layer of the QLEDs. As a result, we provide a way to control the ZnO ETL properties and to improve device performance by controlling O2 partial pressure.
(Received June 14 2021; Accepted July 9, 2021)

KCI등재 SCI SCOPUS

6Charge Transport and Thermoelectric Properties of Sn-Doped Tetrahedrites Cu12Sb4-ySnyS13

저자 : Hee-jae Ahn , Il-ho Kim

발행기관 : 대한금속재료학회 간행물 : 대한금속재료학회지 59권 10호 발행 연도 : 2021 페이지 : pp. 724-731 (8 pages)

다운로드

(기관인증 필요)

초록보기

In this study, tetrahedrite compounds doped with Sn were prepared by mechanical alloying and hot pressing, and their charge transport and thermoelectric properties were analyzed. X-ray diffraction analysis revealed that both the synthetic powders and sintered bodies were synthesized as a single tetrahedrite phase without secondary phases. Densely sintered specimens were obtained with relatively high densities of 99.5%-100.0% of the theoretical density, and the component elements were distributed uniformly. Sn was successfully substituted at the Sb site, and the lattice constant increased from 1.0348 to 1.0364 nm. Positive signs of the Hall and Seebeck coefficients confirmed that the Sn-doped tetrahedrites were p-type semiconductors. The carrier concentration decreased from 1.28 × 1019 to 1.57 × 1018 cm-3 as the Sn content decreased because excess electrons were supplied by doping with Sn4+ at the Sb3+ site of the tetrahedrite. The Seebeck coefficient increased with increasing Sn content, and Cu12Sb3.6Sn0.4S13 exhibited maximum values of 238-270 μVK-1 at temperatures of 323-723 K. However, the electrical conductivity decreased as the amount of Sn doping increased. Thus, Cu12Sb3.9Sn0.1S13 exhibited the highest electrical conductivity of (2.24-2.40) × 104 Sm-1 at temperatures of 323-723 K. A maximum power factor of 0.73 mWm-1K-2 was achieved at 723 K for Cu12Sb3.9Sn0.1S13. Sn substitution reduced both the electronic and lattice thermal conductivities. The lowest thermal conductivity of 0.49-0.60Wm-1K-1 was obtained at temperatures of 323-723 K for Cu12Sb3.6Sn0.4S13, where the lattice thermal conductivity was dominant at 0.49-0.57 Wm-1K-1. As a result, a maximum dimensionless figure of merit of 0.66 was achieved at 723 K for Cu12Sb3.9Sn0.1S13.
(Received July 12, 2021; Accepted July 28, 2021)

KCI등재 SCI SCOPUS

7Glycothermally Synthesized Self-aggregated ZnS Spherical Particles for Methyl Orange Photodecomposition

저자 : Sang-jun Park , Jeong-hwan Song

발행기관 : 대한금속재료학회 간행물 : 대한금속재료학회지 59권 10호 발행 연도 : 2021 페이지 : pp. 732-740 (9 pages)

다운로드

(기관인증 필요)

초록보기

Using ethylene glycol (C2H6O2) as the solvent, ZnS particles were synthesized in high yield at a relatively low temperature of 125 ℃ via the glycothermal method. We report a facile method for preparing spherical self-aggregated ZnS particles from ZnS nanocrystals, using zinc acetate as the Zn2+ source and thiourea as a sulfur source, without mineralization or other agents. The crystal phase structure, morphology, size, surface chemical composition, and optical properties of the self-aggregated ZnS particles were characterized using XRD, FE-SEM, TEM, XPS, BET, and UV-Vis absorption. The ZnS particles had a cubic phase zinc blende structure without any other impurities. The average crystallite size of the synthesized primary nanocrystal, estimated from XRD peak width and TEM images, was nearly 4 nm. FE-SEM images showed that all of the ZnS consisted of self-aggregated particles with a spherical morphology and a size of approximately 0.2 μm~0.5 μm, and contained many tiny primary nanocrystals. The prepared ZnS exhibited strong photoabsorption in the UV region. The optical band gap decreased from 3.85 eV to 3.62 eV as the glycothermal reaction temperature was increased, due to improvement in particle size and crystallization. The effects of the glycothermal reaction temperature on the photocatalytic activity of the synthesized self-aggregated ZnS particles were investigated by the photodecomposition of methyl orange (MO) dye under UV illumination (λ = 365 nm). The prepared ZnS exhibited excellent photocatalytic degradation with increasing reaction temperature, of 125 ℃ (5%), 150 ℃ (10%), 175 ℃ (60%), and 200 ℃ (90%) after irradiation for 60 min. It was found that the ZnS particle prepared at 200 ℃ achieved the highest photocatalytic degradation, with nearly 100% MO decomposition after 90 min, by various photogenerated radical scavengers.
(Received June 9 2021; Accepted July 6, 2021)

KCI등재 SCI SCOPUS

8고분자 전해질 연료전지의 산소환원반응에 대한 Pt-M 합금 촉매의 최근 연구 동향

저자 : 심유진 ( Yu-jin Shim ) , 정원석 ( Won Suk Jung )

발행기관 : 대한금속재료학회 간행물 : 대한금속재료학회지 59권 10호 발행 연도 : 2021 페이지 : pp. 741-752 (12 pages)

다운로드

(기관인증 필요)

초록보기

Due to environmental pollution and global warming, research on new energy sources that can replace fossil fuels is important. A fuel cell is an eco-friendly energy conversion system that discharges water, and uses hydrogen as fuel. Although platinum is a widely used catalyst in PEMFCs, it has commercial limitations because of its low stability and high cost. Pt-based bimetal catalysts are being studied to improve performance and reduce the cost of fuel cell catalysts. Pt-M is excellent in terms of performance, stability, and cost, avoiding the disadvantages of the Pt catalyst. Studies on various bimetallic catalysts have been conducted, and among them, studies on Pt-Ni, Pt-Co, and Pt-Fe have been the most active. This review summarizes reports of fuel cell catalysts using Pt-M from 2014 to 2020. In recent studies, in order to improve the Pt-M performance, there have been attempts to change the pretreatment, the type of support, and the composition of Pt and M. There have also been studies that have applied new synthetic methods, which are different from traditional synthetic methods. Many Pt-M catalysts have shown better performance than commercial Pt/C, and exhibited stable performance in durability tests.
(Received May 29 2021; Accepted July 7, 2021)

KCI등재 SCI SCOPUS

9질소 5N 가스 분위기에서 다공질 ZrFe 합금의 산화 안정화

저자 : 김광배 ( Kwangbae Kim ) , 진새라 ( Saera Jin ) , 임예솔 ( Yesol Lim ) , 이현준 ( Hyunjun Lee ) , 김성훈 ( Seonghoon Kim ) , 노윤영 ( Yunyoung Noh ) , 송오성 ( Ohsung Song )

발행기관 : 대한금속재료학회 간행물 : 대한금속재료학회지 59권 10호 발행 연도 : 2021 페이지 : pp. 753-759 (7 pages)

다운로드

(기관인증 필요)

초록보기

A porous ZrFe alloy specimen was prepared as a 6 × 3 mm (diameter × thickness) disk. The reaction of the ZrFe alloy was confirmed while the whole system was maintained at a target temperature, which was increased from 150 ℃ to 950 ℃ in a 99.999% low purity nitrogen atmosphere, consisting of 10 ppm of impurity gas. Surface color, pore size, stabilized layer, and phase change were confirmed with optical microscopy, scanning electron microscopy-energy dispersive X-ray spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Micro-Raman, according to temperature. The surface color of the ZrFe alloy changed from metallic silver to dark gray as the temperature increased. In the EDS and XPS results, nitrogen component was not observed, and oxygen content increased on each surface at the elevated temperatures. In this way, the ZrFe alloy was stabilized in a low purity nitrogen atmosphere, preventing rapid nitride reactions.
(Received June 1 2021; Accepted July 16, 2021)

1
권호별 보기
같은 권호 다른 논문
| | | | 다운로드

KCI등재SCISCOUPUS

1방전플라즈마 소결법에 의해 제조된 Cu-Ni-Zr-Ti 비정질 기지 복합재료의 미세조직 및 기계적 특성

저자 : 신다운 ( Da Woon Shin ) , 민홍 ( Hong Min ) , 이진규 ( Jin Kyu Lee )

발행기관 : 대한금속재료학회 간행물 : 대한금속재료학회지 59권 5호 발행 연도 : 2021 페이지 : pp. 281-288 (8 pages)

다운로드

(기관인증 필요)

초록보기

In the present study, Cu54Ni6Zr22Ti18 bulk metallic glass composites were developed by spark plasma sintering(SPS) using gas atomized Cu54Ni6Zr22Ti18 metallic glass powders and Ta powders. Metallic glass composites with Ta phase were fabricated by SPS. The successful consolidation of Cu54Ni6Zr22Ti18 metallic glass matrix composites with the Ta phase was achieved through the strong bonding due to the plastic deformation of the Ta powder and the super-plastic behavior of the metallic glass powder in the supercooled liquid state during SPS. The deformed Ta phases were well distributed in the Cu54Ni6Zr22Ti18 metallic glass matrix. The compressive fracture strength and total strain were 1770 Mpa and 10.2%, respectively, for the Cu54Ni6Zr22Ti18 bulk metallic glass composite with 40 wt% Ta phases. The uniformly dispersed deformed Ta phase in the Cu54Ni6Zr22Ti18 metallic glass matrix effectively impedes the propagation of the first shear band and generates a second shear band, causing a crossing of the shear bands, resulting in an improvement in plastic strain. This increase in plastic deformation is related to the fact that the deformed Ta phase, uniformly distributed in the Cu54Ni6Zr22Ti18 metallic glass matrix, acts as a source of shear bands and at the same time effectively suppresses the movement of the shear bands, dispersing the stress and causing wide plastic deformation.
(Received February 24, 2021; Accepted February 25, 2021)

KCI등재SCISCOUPUS

2초음파 분무 열분해법으로 제조한 텅스텐 미세분말의 미세조직과 소결 거동

저자 : 조현희 ( Hyeonhui Jo ) , 김정현 ( Jeong Hyun Kim ) , 이영인 ( Young-in Lee ) , 정영근 ( Young-keun Jeong ) , 오승탁 ( Sung-tag Oh )

발행기관 : 대한금속재료학회 간행물 : 대한금속재료학회지 59권 5호 발행 연도 : 2021 페이지 : pp. 289-294 (6 pages)

다운로드

(기관인증 필요)

초록보기

The powder microstructure and sintering behavior of W prepared by ultrasonic spray pyrolysis and spark plasma sintering were investigated. Fine-grained W powders were synthesized by ultrasonic spray pyrolysis using an ammonium metatungstate hydrate solution and hydrogen reduction. The XRD analysis of the powder, pyrolyzed below 600 ℃, showed tungsten oxide hydrate and WO3 peaks, while the powder pyrolyzed at 700 ℃ was composed of only the WO3 phase. As the precursor concentration increased, the particle size of the WO3 powder increased, which was interpreted to be due to an increase in the amount of solute in the droplet. The hydrogen-reduced powder showed a spherical shape with fine pores inside. XRD and XPS analysis revealed that the WO3 powder was completely reduced to metallic W by hydrogen reduction, and some oxide layers existed on the powder surface. The consolidated specimen prepared by spark plasma sintering of hydrogen-reduced W powder exhibited a relative density of 94.1% and a Vickers hardness value of 3.89 GPa. The relative density and hardness of the specimens prepared by ultrasonic spray pyrolysis showed relatively lower values than when commercial W powder, with an average particle size of 1.22 μm, was sintered under the same conditions. These results were explained by the formation of agglomerates in the W powder prepared by the ultrasonic spray pyrolysis method.
(Received February 23, 2021; Accepted March 15, 2021)

KCI등재SCISCOUPUS

3유가금속 회수를 위한 고로 슬러지의 분산 거동

저자 : 정재헌 ( Jae-heon Jung ) , 이소영 ( So-yeong Lee ) , 최주 ( Joo Choi ) , 손호상 ( Ho-sang Sohn )

발행기관 : 대한금속재료학회 간행물 : 대한금속재료학회지 59권 5호 발행 연도 : 2021 페이지 : pp. 295-303 (9 pages)

다운로드

(기관인증 필요)

초록보기

Blast furnace sludge, which comes from the iron making process, contains many valuable materials including iron, carbon, and zinc, etc. Because a cohesive agent is added during filtration, fine sludge particles are agglomerated together. Therefore, This makes it necessary to disperse the sludge in solution before separating or recovering valuable materials. In this study, the effects of solid/liquid (g/L) ratio, ultrasonic dispersion conditions, the pH of solvent, and the concentration of dispersant on the dispersion of sludge were investigated by measuring the interfacial properties (zeta potential and hydrodynamic size) of sludge particles. High absolute value of zeta potential and small hydrodynamic size suggests that the sludge particles in the solution presents good dispersion. The absolute value of zeta potential increased gradually at high solid/liquid ratio and ultrasonic dispersion intensity. But when the sludge in solution was dispersed for more than 30 minutes, the absolute value of the zeta potential decreased due to increasing contact and interaction between the particles. Optimal dispersion operations were conducted and when the pH of the solution was adjusted to 11, the zeta potential value was measured to be -44.8 mV. This means that the sludge formed the most stable dispersed phase. The lowest zeta potential was measured to be -46.4 mV with the addition of sodium hexametaphosphate (NaPO3)6 in the solution. It is thought that the sodium hexametaphosphate reduced ionic strength by removing alkali metal ions from the solution of sludge.
(Received January 21, 2021; Accepted March 9, 2021)

KCI등재SCISCOUPUS

4고전류밀도에서의 첨가제 초기 거동 및 동박의 기계적 특성

저자 : 우태규 ( Tae-gyu Woo ) , 박종재 ( Jong-jae Park ) , 박일송 ( Il-song Park )

발행기관 : 대한금속재료학회 간행물 : 대한금속재료학회지 59권 5호 발행 연도 : 2021 페이지 : pp. 304-313 (10 pages)

다운로드

(기관인증 필요)

초록보기

In this study, we studied the surface and mechanical properties of multiple additives as well as the initial plating properties of individual additives. With the individual additive groups, copper crystals tended to converge at a stage above the critical amount of additive. When chloride ions were added, large crystals formed at several places on the surface. Thereafter, small crystals were attached to and grew on the surface of the large crystals. When collagen and JGB (Janes Green B) were added individually, the crystals were more uniformly distributed on the surface as compared with the group with added chloride ions. In addition, starlike crystals were grown depending on the amount of addition. It was necessary to use multiple additives, which is why it is difficult to make a uniform surface layer with individual additives. Large crystals of more than 10 μm formed unevenly on the surface treated with multiple additives of chloride ions and MPSA (3-mercapto-1-propane sulfonic acid). Large crystals disappeared on the surface treated with additional collagen along with multiple additives. However, valley like shapes were observed on this surface, due to the large crystals. But, addition of JGB additives to this reduced the valley and formed a uniform plating layer. MPSA and 20 ppm of collagen were added as multiple additives, grain sizes increased by 93.5% (220 peak) and 172.3% (311 peak) compared with the non-additive group. As a result, tensile strength decreased by 24.5% and elongation increased by 17.8%. The crystal size was reduced 25.0% on average by the addition of 10 ppm JGB, which contributed to a 5.4% increase in tensile strength and a 16.0% decrease in elongation. The grain size and surface properties could be controlled by adding multiple combinations of additives. As a result, It was confirmed that mechanical properties could be controlled by the proper amount and the optimum combination of additives.
(Received November 3, 2020; Accepted November 18, 2020)

KCI등재SCISCOUPUS

5잉크젯 인쇄 기술을 이용하여 상대적으로 낮은 온도에서 리튬이 도핑 된 인듐-아연-산화물 트랜지스터의 제작

저자 : 최운섭 ( Woon-seop Choi )

발행기관 : 대한금속재료학회 간행물 : 대한금속재료학회지 59권 5호 발행 연도 : 2021 페이지 : pp. 314-320 (7 pages)

다운로드

(기관인증 필요)

초록보기

Inkjet printing is a very attractive technology for printed electronics and a potential alternative to current high cost and multi-chemical lithography processes, for display and other applications in the electronics field. Inkjet technology can be employed to fabricate organic light emitting diodes (OLED), quantum dots displays, and thin-film transistors (TFTs). Among potential applications, metal oxide TFTs, which have good properties and moderate processing methods, could be prepared using inkjet printing in the display industry. One effective method of improving their electrical properties is via doping. Lithium doping an oxide TFT is a very delicate process, and difficult to get good results. In this study, lithium was added to indium-zinc oxide (IZO) for inkjet printing to make oxide TFTs. Electrical properties, transfer and output curves, were achieved using inkjet printing even at the relatively low annealing temperature of 200 ℃. After optimizing the inkjet process parameters, a 0.01 M Li-doped IZO TFT at 400 ℃ showed a mobility of 9.08 ± 0.7 cm2/V s, a sub-threshold slope of 0.62 V/dec, a threshold voltage of 2.66 V, and an on-to-off current ratio of 2.83 × 108. Improved bias stability and hysteresis behavior of the inkjet-printed IZO TFT were also achieved by lithium doping.
(Received January 11, 2021; Accepted February 24, 2021)

KCI등재SCISCOUPUS

6A-site 조성 제어를 통한 FA기반 페로브스카이트의 상안정화 및 전단 코팅 최적화 연구

저자 : 김한솔 ( Hansol Kim ) , 구혜원 ( Hyewon Gu ) , 송민주 ( Minju Song ) , 정중희 ( Choong-heui Chung ) , 오용준 ( Yong-jun Oh ) , 송창은 ( Chang Eun Song ) , 홍기하 ( Ki-ha Hong )

발행기관 : 대한금속재료학회 간행물 : 대한금속재료학회지 59권 5호 발행 연도 : 2021 페이지 : pp. 321-328 (8 pages)

다운로드

(기관인증 필요)

초록보기

Halide perovskite solar cells have been attracting tremendous attention as next-generation solar cell materials because of their excellent optical and electrical properties. Formamidinium lead tri-iodide (FAPbI3) exhibits the narrowest band gap among lead iodide perovskites and shows excellent thermal and chemical stability, also. However, the large-area coating of FAPbI3 needed for commercialization has not been successful because of the instability of the black phase of FAPbI3 at ambient temperature. This study presents a compositional engineering direction to control the polymorph of the FAPbI3 thin film for the shear coating processes, without halide mixing. By adopting a hot substrate above 100 ℃, our shear coating process can produce the black phase FA-based halide perovskites without halide mixing. We carefully investigate the Cs- FA and MA-FA mixed lead iodide perovskites' phase stability by combining the study with thin-film fabrication and ab initio calculations. Cs-FA mixing shows promising behaviors for stabilizing α-FAPbI3 (black phase) compared with MA-FA. Stable FA-rich perovskite films cannot be achieved via shear coating processes with MA-FA mixing. Ab initio calculations revealed that Cs-FA mixing is excellent for inhibiting phase decomposition and water incorporation. This study is the first report that FA-based halide perovskite thin films can be made with the shear coating process without MA-Br mixing. We reveal the origin of the stable film formation with Cs-FA mixing, and present future research directions for fabricating FA-based perovskite thin films using shear coating.
(Received January 14, 2021; Accepted March 4, 2021)

KCI등재SCISCOUPUS

7Charge Transport and Thermoelectric Properties of Mn-Doped Tetrahedrites Cu12-xMnxSb4S13

저자 : Sung-yoon Kim , Go-eun Lee , Il-ho Kim

발행기관 : 대한금속재료학회 간행물 : 대한금속재료학회지 59권 5호 발행 연도 : 2021 페이지 : pp. 329-335 (7 pages)

다운로드

(기관인증 필요)

초록보기

Mn-doped tetrahedrites Cu12-xMnxSb4S13 (0.1 ≤ x ≤ 0.4) were synthesized by mechanical alloying (MA) and sintered by hot pressing (HP). A single tetrahedrite phase was synthesized by MA without post-annealing, and it was stable without any phase changes after HP. The hot-pressed specimens had a relative density higher than 98.6%. The lattice constant of the Mn-doped samples increased compared to that of undoped Cu12Sb4S13, but no significant change in the lattice constant was observed with a change in Mn content. All Mn-doped tetrahedrites acted as p-type semiconductors, as confirmed from positive Hall and Seebeck coefficient values. The Seebeck coefficient increased with increasing temperature but decreased with increasing Mn content; maximum Seebeck coefficient values of 200-219 μVK-1 were obtained at 323-723 K for x = 0.1. Electrical conductivity increased with increasing temperature and Mn content; the highest electrical conductivity values of (1.76-2.45) × 104 Sm-1 were obtained at 323-723 K for x = 0.4. As a result, Cu11.6Mn0.4Sb4S13 exhibited a maximum power factor of 0.80 mWm-1K-2 at 723 K. As the Mn content increased, both the electronic and lattice thermal conductivities increased, and thus, the total thermal conductivity was the lowest at 0.48-0.63Wm-1K-1 at 323-723 K for x = 0.1. A maximum dimensionless figure of merit of 0.75 was obtained at 723 K for Cu11.7Mn0.3Sb4S13. The MA-HP process is suitable for preparing doped tetrahedrites exhibiting excellent thermoelectric performance.
(Received February 18, 2021; Accepted March 2, 2021)

KCI등재SCISCOUPUS

81,8-Diazabicyclo[5.4.0]undec-7-ene (DBU)의 탈불화를 이용한 PVDF와 PTFE로부터 메조포러스 탄소의 합성

저자 : 손인식 ( In-sik Son ) , 황버들 ( Beodl Hwang ) , 전상은 ( Sang-eun Chun )

발행기관 : 대한금속재료학회 간행물 : 대한금속재료학회지 59권 5호 발행 연도 : 2021 페이지 : pp. 336-345 (10 pages)

다운로드

(기관인증 필요)

초록보기

Porous carbon has found commercial applications as a filter material based on the sorption ability of its pores. The pore size and surface properties of the carbon can be varied depending on the type of particles to be filtered. Here, mesoporous carbon was induced through the pyrolysis of polyvinylidene fluoride (PVDF) to fabricate a porous material for microparticle filtration. Because removal of the constituent fluorine at elevated temperature leaves small-sized micropores, the PVDF precursor mainly generates micropores during pyrolysis. To suppress the micropore evolution mechanism, the PVDF precursor was defluorinated before the heat treatment using 1,8-Diazabicyclo[5.4.0]undec-7-ene(DBU) and then pyrolyzed. The suppressed evolution of the micropores during carbon synthesis leads to a lower specific surface area, suggesting low adsorption capacity. The polytetrafluoroethylene (PTFE) was mixed with the PVDF precursor to induce mesoporosity. The PVDF precursor mixed with the PTFE enhanced the surface area since the PTFE could be removed, leaving mesopores after pyrolysis. The effect of the defluorination process on the porosity was investigated by varying the ratio of DBU to vinylidene fluoride unit (1, 5, 10, 20) in the precursor solution. With higher DBU content in the precursor, the micropore evolution was reduced with a lower specific surface area. The porous carbons synthesized from the precursor with a high DBU amount (DBU/vinylidene fluoride unit = 5, 10, 20) were almost entirely composed of mesopores. In addition, the higher DBU content reduced the hydrophilicity of the synthesized carbon. In summary, to separate and absorb relatively large impurities, the mesoporous carbon should be synthesized using a mixture of PVDF and PTFE precursor with an appropriate amount of DBU for a higher specific surface area.
(Received February 17, 2021; Accepted March 18, 2021)

KCI등재SCISCOUPUS

9Ultraviolet Light-Responsive Photorheological Fluid for Sensors and Actuators Realized by Phosphorescence Effects and LSTM RNN

저자 : Min Young Cho , Suman Timilsina , Jong Wook Roh , Walter Commerell , Ho Geun Shin , Yong-nam Kwon , Ji Sik Kim

발행기관 : 대한금속재료학회 간행물 : 대한금속재료학회지 59권 5호 발행 연도 : 2021 페이지 : pp. 346-353 (8 pages)

다운로드

(기관인증 필요)

초록보기

A photo-rheological fluid (PRF) is a smart fluid which exhibits different viscosity under UV irradiation. A PRF is comprehensively presented in this work, with particular focus on its responses under UV off/on conditions. The isomeric conversion from SP to MC and vice versa under UV off and on, respectively, showed unequal rates of transformation. As a result, a complex non-linear hysteretic response was observed. To be used indifferent types of sensors and actuators which can exploit its rheological properties, it is essential the PRF have linearized hysteresis behavior. To minimize the asymmetric non-linear hysteresis characteristics under UV on and off conditions, the well-known long-lasting phosphor SAO (SrAl2O4:Eu2+, Dy3+) was incorporated. The incorporation of SAO in the PRF improved the linearity of the PRF response, although the conversion rate was not identical under UV off/on conditions. The SAO particles were observed to settle over time due to phase splitting, undermining the usefulness of the SAO-PRF composite. Instead of improving the PRF response by further adjusting the PRF composite, a software approach based on Long Short-Term Memory Recurrent Neural Networks (LSTM RNN) was employed to model and compensate the asymmetric non-linear hysteresis response, ensuring the realization of sensors and actuators that exploit PRF as hardware.
(Received March 2, 2021; Accepted March 5, 2021)

KCI등재SCISCOUPUS

10Erratum to: 니알브론즈의 기계적 특성에 미치는 알루미늄 및 지르코늄 함량의 영향

저자 : 안지혁 ( Jee Hyuk Ahn ) , 김동욱 ( Dong Wook Kim ) , 김민수 ( Min Soo Kim ) , 황종현 ( Jong-hyun Hwang ) , 한승전 ( Seung Zeon Han )

발행기관 : 대한금속재료학회 간행물 : 대한금속재료학회지 59권 5호 발행 연도 : 2021 페이지 : pp. 354-354 (1 pages)

다운로드

(기관인증 필요)

키워드 보기
초록보기
12
발행기관 최신논문
자료제공: 네이버학술정보
발행기관 최신논문
자료제공: 네이버학술정보

내가 찾은 최근 검색어

최근 열람 자료

맞춤 논문

보관함

내 보관함
공유한 보관함

1:1문의

닫기