Journal of Powder Materials

Yoo-Jin Kim

7 Articles

Synthesis and Characterization of CuInS₂ Semiconductor Nanoparticles and Evolution of Optical Properties via Surface Modification: Hee-Seung Yang, Yoo-Jin Kim; J Korean Powder Metall Inst. 2012;19(3):177-181.; DOI: https://doi.org/10.4150/KPMI.2012.19.3.177

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Copper composite materials have attracted wide attention for energy applications. Especially CuInS_2 has a desirable direct band gap of 1.5 eV, which is well matched with the solar spectrum. CuInS_2 nanoparticles could make it possible to develop color-tunable CuInS_2 nanoparticle emitter in the near-infrared region (NIR) for energy application and bio imaging sensors. In this paper, CuInS_2 nanoparticles were successfully synthesized by thermo-decomposition methods. Surface modification of CuInS_2 nanoparticles were carried out with various semiconductor materials (CdS, ZnS) for enhanced optical properties. Surface modification and silica coating of hydrophobic nanoparticles could be dispersed in polar solvent for potential applications. Their optical properties were characterized by UV-vis spectroscopy and photoluminescence spectroscopy (PL). The structures of silica coated CuInS_2 were observed by transmission electron microscopy (TEM).

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Surface Treatment Method for Long-term Stability of CdSe/ZnS Quantum Dots
Hyun-Su Park, Da-Woon Jeong, Bum-Sung Kim, So-Yeong Joo, Chan-Gi Lee, Woo-Byoung Kim
Journal of Korean Powder Metallurgy Institute.2017; 24(1): 1. CrossRef
Effect of Carboxylic Acid on Optical Properties of CuInS2/ZnS Semiconductor Nanocrystals
Si-Hyun Ahn, Gyu-Che Choi, Yeun-Kyung Beak, Young-Kuk Kim, Yang-Do Kim
Journal of Korean Powder Metallurgy Institute.2012; 19(5): 362. CrossRef

Effect of MgO and NH₄OH on Formation of 5Mg(OH)₂·MgSO₄·3H₂O Whiskers: Ri Yu, Jae-Hwan Pee, Hyung-Tae Kim, Kyung-Ja Kim, Young-Woong Kim, Woong Kim, Yoo-Jin Kim; J Korean Powder Metall Inst. 2011;18(3):283-289.; DOI: https://doi.org/10.4150/KPMI.2011.18.3.283

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Magnesium hydroxide sulfate hydrate whiskers (5Mg(OH)_2cdotMgSO_4cdot3H_2O, abbreviated 513 MHSH) were prepared using hydrothermal reaction with magnesium oxide (MgO) and magnesium sulfate (MgSO_4cdot7H_2O) as the starting materials. The effects of the molar ratio of MgSO_4/MgO and amount of NH_4OH were studied. As a result, 513 MHSH whiskers co-existed with hexagonal plate Mg(OH)_2 at low concentration of SO_42-. The molar ratio of MgSO_4cdot7H_2O/MgO was 7:1, uniform 513 MHSH whiskers were formed without impurity such as Mg(OH)_2. Appropriate amount of NH_4OH has affected to formation of high quality MHSH. Their morphologies and structures were determined by powder X-ray diffraction (XRD) scanning electron microscopy (SEM) and thermo-gravimetric analyzer (TGA).

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Effect of sulfate ion on synthesis of 5 Mg(OH)2·MgSO4·3H2O whiskers using non-hydrothermal method with acid catalyst
Areum Choi, Nuri Oh, YooJin Kim
Journal of the Korean Ceramic Society.2022; 59(2): 224. CrossRef
Effect of H₂SO₄ and Reaction Time on Synthesis of 5Mg(OH)₂∙MgSO₄∙3H₂O Whiskers using Hydrothermal Reaction
Areum Choi, Nuri Oh, YooJin Kim
Journal of Korean Powder Metallurgy Institute.2020; 27(5): 401. CrossRef
Study of Fabrication and Improvement of Mechanical Properties of Mg-based Inorganic Fiber using Reflux Process and Silica Coating
Ri Yu, YooJin Kim
Journal of Korean Powder Metallurgy Institute.2019; 26(3): 195. CrossRef
Effect of MgSO4/MgO on the Synthesis of 5Mg(OH)2·MgSO4·3H2O Whiskers using One-step Ambient Pressure
Ri Yu, Jae-Hwan Pee, Hyung Tae Kim, YooJin Kim
Journal of the Korean Ceramic Society.2013; 50(3): 201. CrossRef

Synthesis of LiCoO₂ Powders using Recycled Cobalt Precursors from Waste WC-Co Hard Metal: Hee-Seung Yang, Jae-Hwan Pee, Yoo-Jin Kim; J Korean Powder Metall Inst. 2011;18(3):277-282.; DOI: https://doi.org/10.4150/KPMI.2011.18.3.277

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[ LiCoO_2 ] a cathode material for lithium rechargeable batteries, was prepared using recycled Co_3O_4. First, the cobalt hydroxide powders were separated from waste WC-Co hard metal with acid-base chemical treatment, and then the impurities were eliminated by centrifuge method. Subsequently, Co_3O_4 powders were prepared by thermal treatment of resulting Co(OH)_2. By adding a certain amount of Li_2CO_3 and LiOHcdotH_2O, the LiCoO_2 was obtained by sintering for 10 h in air at 800°C. The synthesized LiCoO_2 particles were characterized by X-ray diffraction (XRD) and Scanning Electron Microscope (SEM) analysis.

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Fabrication of Flake-like LiCoO2Nanopowders using Electrospinning
Bon-Ryul Koo, Geon-Hyoung An, Hyo-Jin Ahn
Journal of Korean Powder Metallurgy Institute.2014; 21(2): 108. CrossRef

Thickness Control of Core Shell type Nano CoFe₂O₄@SiO₂ Structure: Ri Yu, Yoo-Jin Kim, Jae-Hwan Pee, Kyung-Ja Kim; J Korean Powder Metall Inst. 2010;17(3):230-234.; DOI: https://doi.org/10.4150/KPMI.2010.17.3.230

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Abstract PDF: Homogenous silica-coated CoFe_2O_4 samples with controlled silica thickness were synthesized by the reverse microemulsion method. First, 7 nm size cobalt ferrite nanoparticles were prepared by thermal decomposition methods. Hydrophobic cobalt ferrites were coated with controlled SiO_2 using polyoxyethylene(5)nonylphenylether (Igepal) as a surfactant, NH_4OH and tetraethyl orthosilicate (TEOS). The well controlled thickness of the silica shell was found to depend on the reaction time and the amount of surfactant used during production. Thick shell was prepared by increasing reaction time and small amount of surfactant.

Effects of Doping Elements and the Amounts of Oxygen/Nitrogen Contents in Final Nitrides on the Characteristics of Red Pigment of Tantalum Nitrides (Ta₃N₅): Eun-Young Park, Jae-Hwan Pee, Yoo-Jin Kim, Woo-Seok Cho, Kyeong-Ja Kim; J Korean Powder Metall Inst. 2009;16(6):396-402.; DOI: https://doi.org/10.4150/KPMI.2009.16.6.396

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Abstract PDF: Tantalum nitrides (Ta_3N_5) have been developed to substitute the Cd based pigments for non-toxic red pigment. Various doping elements were doped to reduce the amount of high price Tantalum element used and preserve the red color tonality. Doping elements were added in the synthesizing process of precursor of amorphous tantalum oxides and then Tantalum nitrides doped with various elements were obtained by ammonolysis process. The average particle size of final nitrides with secondary phases was larger than the nitride without the secondary phases. Also secondary phases reduced the red color tonality of final products. On the other hand, final nitrides without secondary phase had orthorhombic crystal system and presented good red color. In other words, in the case of nitrides without secondary phases, doping elements made a solid solution of tantalum nitride. In this context, doping process controlled the ionic state of nitrides and the amount of oxygen/nitrogen in final nitrides affected the color tonality.

Synthesis of Nano-size Aluminum Nitride Powders by Chemical Vapor Process: Jae-Hwan Pee, Jong-Chul Park, Yoo-Jin Kim, Kwang-Taek Hwang, So-Ryong Kim; J Korean Powder Metall Inst. 2008;15(6):496-502.; DOI: https://doi.org/10.4150/KPMI.2008.15.6.496

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Aluminum nitride (AlN) powders were prepared by the chemical vapor synthesis (CVS) process in the AlCl_3-NH_3-N_2 system. Aluminum chloride (AlCl_3) as the starting material was gasified in the heating chamber of 300°C. Aluminum chloride gas transported to the furnace in NH_3-N_2 atmosphere at the gas flow rate of 200-400ml/min. For samples synthesized between 700 and 1200°C, the XRD peaks corresponding to AlN were comparatively sharp and also showed an improvement of crystallinity with increasing the reaction temperature. In additions, the average particle size of the AlN powders decreased from 250 to 40 nm, as the reaction temperature increased.

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A Scale-Up Test for Preparation of AlN by Carbon Reduction and Subsequent Nitridation Method
Hyung-Kyu Park, Sung-Don Kim, Chul-Woo Nam, Dae-Woong Kim, Moon-Soo Kang, Gwang-Hee Shin
Journal of the Korean Institute of Resources Recycling.2016; 25(5): 75. CrossRef
Synthesis of High Purity Aluminum Nitride Nanopowder in Ammonia and Nitrogen Atmosphere by RF Induction Thermal Plasma
Kyung-In Kim, Sung-Churl Choi, Jin-Ho Kim, Kwang-Taek Hwang, Kyu-Sung Han
Journal of the Korean Ceramic Society.2014; 51(3): 201. CrossRef
Synthesis of an aluminum nitride–yttria (AlN–Y2O3) composite from nano-sized porous AlN and YCl3
Jae-Hwan Pee, Jong-Chul Park, Kwang-Taek Hwang, SooRyong Kim, Woo-Seok Cho
Research on Chemical Intermediates.2010; 36(6-7): 801. CrossRef

Synthesis of Tantalum Oxy-nitride and Nitride using Oxygen Dificiency Tantalum Oxides: Jong-Chul Park, Jae-Hwan Pee, Yoo-Jin Kim, Eui-Seock Choi; J Korean Powder Metall Inst. 2008;15(6):489-495.; DOI: https://doi.org/10.4150/KPMI.2008.15.6.489

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Abstract PDF: Colored tantalum oxy-nitride (TaON) and tantalum nitride (Ta_3N_5) were synthesized by ammonolysis. Oxygen deficient tantalum oxides (TaO_1.7) were produced by a titration process, using a tantalum chloride (TaCl_5) precursor. The stirring speed and the amount of NH_4OH were important factors for controling the crystallinity of tantalum oxides. The high crystallinity of tantalum oxides improved the degree of nitridation which was related to the color value. Synthesized powders were characterized by XRD, SEM, TEM and Colorimeter.

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