In this study, we prepare polymer solar cells incorporating organic ligand-modified Ag nanoparticles (OAgNPs) highly dispersed in the P3HT:PCBM layer. Ag nanoparticles decorated with water-dispersible ligands (WAgNPs) were also utilized as a control sample. The existence of the ligands on the Ag surface was confirmed by FTIR spectra. Metal nanoparticles with different surface chemistries exhibited different dispersion tendencies. O-AgNPs were highly dispersed even at high concentrations, whereas W-AgNPs exhibited significant aggregation in the polymer layer. Both dispersion and blending concentration of the Ag nanoparticles in P3HT:PCBM matrix had critical effects on the device performance as well as light absorption. The significant changes in short-circuit current density (J_SC) of the solar cells seemed to be related to the change in the polymer morphology according to the concentration of AgNPs introduced. These findings suggested the importance of uniform dispersion of plasmonic metal nanoparticles and their blending concentration conditions in order to boost the solar cell performance.

FeS₂ has been widely used for cathode materials in thermal battery because of its high stability and current capability at high operation temperature. Salts such as a LiCl-KCl were added as a binder for improving electrical performance and formability of FeS₂ cathode powder. In this study, the effects of the addition of Li₂O in LiCl-KCl binder on the formability of FeS₂ powder compact were investigated. With the increasing amount of Li₂O addition to LiCl-KCl binder salts, the strength of the pressed compacts increased considerably when the powder mixture were pre-heat-treated above 350°C. The heat-treatment resulted in promoting the coating coverage of FeS₂ particles by the salts as Li₂O was added. The observed coating as Li₂O addition might be attributed to the enhanced wettability of the salt rather than its reduced melting temperature. The high strength of compacts by the Li₂O addition and pre-heat-treatment could improve the formability of FeS₂ raw materials.

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• Effects of Particle Size and Binder Phase Addition on Formability of Li-Si Alloy Powder for Thermal Battery Anode
  Sung-Soo Ryu, Hui-Sik Kim, Seongwon Kim, Hyung-Tae Kim, Hae-Won Cheong, Sung-Min Lee
  Journal of Korean Powder Metallurgy Institute.2014; 21(5): 331.     CrossRef

This study reports a simple way of fabricating the porous Cu with unidirectional pore channels by freeze drying camphene slurry with Cu oxide coated Cu powders. The coated powders were prepared by calcination of ballmilled powder mixture of Cu and Cu-nitrate. Improved dispersion stability of camphene slurry could be achieved using the Cu oxide coated Cu powders instead of pure Cu powders. Pores in the frozen specimen at -25°C were generated by sublimation of the camphene during drying in air, and the green bodies were sintered at 750°C for 1 h in H₂ atmosphere. XRD analysis revealed that the coated layer of Cu oxide was completely converted to Cu phase without any reaction phases by hydrogen heat treatment. The porous Cu specimen prepared from pure Cu powders showed partly large pores with unidirectional pore channels, but most of pores were randomly distributed. In contrast, large and aligned parallel pores to the camphene growth direction were clearly observed in the sample using Cu oxide coated Cu powders. Pore formation behavior depending on the initial powders was discussed based on the degree of powder rearrangement and dispersion stability in slurry.

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• Effect of Freezing and Sintering Condition of CuO-SnO2/Camphene Slurries on the Pore Structure of Porous Cu-Sn
  Joo-Hyung Kim, Sung-Tag Oh, Chang-Yong Hyun
  Journal of Korean Powder Metallurgy Institute.2016; 23(1): 49.     CrossRef
• Fabrication of Cu-30 vol% SiC Composites by Pressureless Sintering of Polycarbosilane Coated SiC and Cu Powder Mixtures
  Yeon Su Kim, Na-Yeon Kwon, Young-Keun Jeong, Sung-Tag Oh
  Korean Journal of Materials Research.2016; 26(6): 337.     CrossRef
• Synthesis of Aligned Porous Sn by Freeze-Drying of Tin Chloride/camphene Slurry
  수룡 방, 승탁 오
  Korean Journal of Materials Research.2015; 25(1): 27~31.     CrossRef

In this study, nanocrystalline Cu-Ni bulk materials with various compositions were cold compacted by a shock compaction method using a single-stage gas gun system. Since the oxide layers on powder surface disturbs bonding between powder particles during the shock compaction process, each nanopowder was hydrogen-reduced to remove the oxide layers. X-ray peak analysis shows that hydrogen reduction successfully removed the oxide layers from the nano powders. For the shock compaction process, mixed powder samples with various compositions were prepared using a roller mixer. After the shock compaction process, the density of specimens increased up to 95% of the relative density. Longitudinal cross-sections of the shock compacted specimen demonstrates that a boundary between two powders are clearly distinguished and agglomerated powder particles remained in the compacted bulk. Internal crack tended to decrease with an increase in volumetric ratio of nano Cu powders in compacted bulk, showing that nano Cu powders has a higher coherency than nano Ni powders. On the other hand, hardness results are dominated by volume fraction of the nano Ni powder. The crystalline size of the shock compacted bulk materials was greatly reduced from the initial powder crystalline size since the shock wave severely deformed the powders.

Leaching of MOCVD dust in the LED industry is an essential stage for hydro-metallurgical recovery of pure Ga and In. To recover Ga and In, the leaching behavior of MOCVD scrap of an LED, which contains significant amounts of Ga, In, Al and Fe in various phases, has been investigated. The leaching process must be performed effectively to maximize recovery of Ga and In metals using the most efficient lixiviant. Crystalline structure and metallic composition of the raw MOCVD dust were analyzed prior to digestion. Subsequently, various mineral acids were tested to comprehensively study and optimize the leaching parameters such as acidity, pulp density, temperature and time. The most effective leaching of Ga and In was observed for a boiling 4 M HCl solution vigorously stirred at 400 rpm. Phase transformation of GaN into gallium oxide by heat treatment also improved the leaching efficiency of Ga. Subsequently high purity Ga and In can be recovered by series of hydro processes.

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• Selective Solvent Extraction of In from Synthesis Solution of MOCVD Dust using D2EHPA
  Byoungyong Im, Basudev Swain, Chan Gi Lee, Jae Layng Park, Kyung-Soo Park, Jong-Gil Shim, Jeung-Jin Park
  Journal of the Korean Institute of Resources Recycling.2015; 24(5): 80.     CrossRef
• Fabrication of High Purity Ga-containing Solution using MOCVD dust
  Duk-Hee Lee, Jin-Ho Yoon, Kyung-Soo Park, Myung-Hwan Hong, Chan-Gi Lee, Jeung-Jin Park
  Journal of the Korean Institute of Resources Recycling.2015; 24(4): 50.     CrossRef
• Influence of Oxidation Temperatures on the Structure and the Microstructure of GaN MOCVD Scraps
  Hyun Seon Hong, Joong Woo Ahn
  journal of Korean Powder Metallurgy Institute.1970; 22(4): 278.     CrossRef

In this study, nano-scale copper powders were reduction treated in a hydrogen atmosphere at the relatively high temperature of 350°C in order to eliminate surface oxide layers, which are the main obstacles for fabricating a nano/ultrafine grained bulk parts from the nano-scale powders. The changes in composition and microstructure before and after the hydrogen reduction treatment were evaluated by analyzing X-ray diffraction (XRD) line profile patterns using the convolutional multiple whole profile (CMWP) procedure. In order to confirm the result from the XRD line profile analysis, transmitted electron microscope observations were performed on the specimen of the hydrogen reduction treated powders fabricated using a focused ion beam process. A quasi-statically compacted specimen from the nanoscale powders was produced and Vickers micro-hardness was measured to verify the potential of the powders as the basis for a bulk nano/ultrafine grained material. Although the bonding between particles and the growth in size of the particles occurred, crystallites retained their nano-scale size evaluated using the XRD results. The hardness results demonstrate the usefulness of the powders for a nano/ultrafine grained material, once a good consolidation of powders is achieved.

Translucent alumina is a potential candidate for high temperature application as a replacement of the glass or polymer. Recently, due to the increasing demand of high power light emitting diode (LED), there is a growing interest in the translucent alumina. Since the translucent property is very sensitive to the internal defect, such as voids inside or abnormal grain growth of sintered alumina, it is important to fabricate the defect-free product through the fabrication process. Powder injection molding (PIM) has been commonly applied for the fabrication of complex shaped products. Among the many parameters of PIM, the flowability of powder/binder mixture becomes more significant especially for the shape of the cavity with thin thickness. Two different positions of the gate were applied during PIM using the disc type of die. The binder was removed by solvent extraction method and the brown compact was sintered at 1750°C for 3 hours in a vacuum. The flowability was also simulated using moldflow (MPI 6.0) with two different types of gate. The effect of the flowability of powder/binder mixture on the microstructure of the sintered specimen was studied with the analysis of the simulation result.

Much research into fuel cells operating at a temperature below 800°C. is being performed. There are significant efforts to replace the yttria-stabilized zirconia electrolyte with a doped ceria electrolyte that has high ionic conductivity even at a lower temperature. Even if the doped ceria electrolyte has high ionic conductivity, it also shows high electronic conductivity in a reducing environment, therefore, when used as a solid electrolyte of a fuel cell, the powergeneration efficiency and mechanical properties of the fuel cell may be degraded. In this study, gadolinium-doped ceria nanopowder with Al₂O₃ and Mn₂O₃ as a reinforcing and electron trapping agents were synthesized by ultrasonic pyrolysis process. After firing, their microstructure and mechanical and electrical properties were investigated and compared with those of pure gadolinium-doped ceria specimen.

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• High growth-rate atomic layer deposition process of cerium oxide thin film for solid oxide fuel cell
  Jin-Geun Yu, Byung Chan Yang, Jeong Woo Shin, Sungje Lee, Seongkook Oh, Jae-Ho Choi, Jaehack Jeong, Wontae Noh, Jihwan An
  Ceramics International.2019; 45(3): 3811.     CrossRef
• Atomic-layer-deposited ZrO2-doped CeO2 thin film for facilitating oxygen reduction reaction in solid oxide fuel cell
  Byung Chan Yang, Dohyun Go, Seongkook Oh, Jeong Woo Shin, Hyong June Kim, Jihwan An
  Applied Surface Science.2019; 473: 102.     CrossRef

This study manufactured a CIG-based composite coating layer utilizing a new warm spray process, and a mixed powder of Cu-20at.%Ga and Cu-20at.%In. In order to obtain the mixed powder with desired composition, the Cu-20at.%Ga and Cu-20at.%In powders were mixed with a 7:1 ratio. The mixed powder had an average particle size of 35.4 μm. Through the utilization of a warm spray process, a CIG-based composite coating layer of 180 μm thickness could be manufactured on a pure Al matrix. To analyze the microstructure and phase, the warm sprayed coating layer underwent XRD, SEM/EDS and EMPA analyses. In addition, to improve the physical properties of the coating layer, an annealing heat treatment was conducted at temperatures of 200°C, 400°C and 600°C for 1 hour each. The microstructure analysis identified α-Cu, Cu₄In and Cu₃Ga phases in the early mixed powder, while Cu₄In disappeared, and additional Cu₉In₄ and Cu₉Ga₄ phases were identified in the warm sprayed coating layer. Porosity after annealing heat treatment reduced from 0.75% (warm sprayed coating layer) to 0.6% (after 600°C/1 hr. heat treatment), and hardness reduced from 288 Hv to 190 Hv. No significant phase changes were found after annealing heat treatment.

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• Fabrication and Microstructure/Properties of Bulk-typeTantalum Material by a Kinetic Spray Process
  Ji-Hye Lee, Ji-Won Kim, Kee-Ahn Lee
  Journal of Korean Powder Metallurgy Institute.2016; 23(1): 8.     CrossRef
• Effect of Heat Treatment Environment on the Microstructure and Properties of Kinetic Sprayed Tantalum Coating Layer
  Ji-Hye Lee, Hyung-Jun Kim, Kee-Ahn Lee
  Journal of Korean Powder Metallurgy Institute.2015; 22(1): 32.     CrossRef

The basis of the cobalt demand analysis by use was established via the investigation and analysis of the cobalt materials flow, and the overall cobalt metal material and parts industry structure in Korea was examined to determine the cobalt material flow. The markets of the cobalt material for machinery were studied, including their interrelations, via market and study trends, and relevant plans were examined. The results of the study indicated that the advanced core technology for advanced industry and technology-intensive industry development is required to structurally innovate the parts materials and basic materials industries and to upgrade the catch-up industry structure to the new frontier structure.

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• Exploring the potential for improving material utilization efficiency to secure lithium supply for China's battery supply chain
  Xin Sun, Han Hao, Yong Geng, Zongwei Liu, Fuquan Zhao
  Fundamental Research.2024; 4(1): 167.     CrossRef
• Trade structure and risk transmission in the international automotive Li-ion batteries trade
  Xiaoqian Hu, Chao Wang, Xiangyu Zhu, Cuiyou Yao, Pezhman Ghadimi
  Resources, Conservation and Recycling.2021; 170: 105591.     CrossRef