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[Korean]
Enhanced H2S Gas Sensing Using ZnO Porous Nanorod Synthesized via a Rotational Hydrothermal Method
Jimyeong Park, Changyu Kim, Minseo Kim, Jiyeon Shin, Jae-Hyoung Lee, Myung Sik Choi
J Powder Mater. 2025;32(5):406-415.   Published online October 31, 2025
DOI: https://doi.org/10.4150/jpm.2025.00262
  • 123 View
  • 3 Download
AbstractAbstract PDF
In this study, ZnO porous nanorods were synthesised using a rotational hydrothermal process, and their performance as hydrogen sulphide (H2S) gas sensors was analysed. Compared to commercial ZnO nanoparticles and conventionally hydrothermally synthesised ZnO nanorods, the ZnO porous nanorods exhibited a more uniform structure and improved crystal growth in the (002) plane, with surfaces rich in porosity and oxygen vacancies. These structural and chemical characteristics significantly improved the sensitivity toward H2S, showing high detection performance at 250°C across various concentrations of H2S gas. Additionally, the sensor demonstrated excellent selectivity against other gases such as C2H5OH, C6H6, C7H8, and NH3. This study indicated that the rotational hydrothermal process is an effective method for developing high-performance ZnO-based gas sensors and suggests its applicability to other metal oxide materials.
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[Korean]
3D-Printed Stretchable Electrodes Enabled by a Titanium/Acrylamide-Based Hydrogel Nanocomposite
Se Jin Choi, Han Eol Lee
J Powder Mater. 2025;32(1):67-72.   Published online February 28, 2025
DOI: https://doi.org/10.4150/jpm.2024.00465
  • 593 View
  • 15 Download
AbstractAbstract PDF
Wearable electronics have been the focus of considerable interest in various fields, such as human-machine interfaces, soft robotics, and medical treatments, due to their flexibility, stretchability, and light weight. To address the shortcomings of existing metal thin film-based wearable devices, stretchable conductive polymers have been developed. In particular, double networking hydrogels are being actively studied as a polymer with a three-dimensional stereoscopic structure that can be patterned. Nonetheless, they have shortcomings such as poor electrical properties and cumbersome manufacturing processes, making it difficult to apply them in electronic devices. Herein, we report 3D-printed stretchable electrodes enabled by a titanium/polyacrylamide-alginate-based hydrogel nanocomposite. This research suggests the strategy for resolving the challenges of high costs and complex fabrication processes associated with stretchable electrode, providing a solution to accelerate the commercialization of wearable electronic devices.
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[English]
The Effect of a CNT/MnO2 Nanoparticle Composite–Based Multi-Shell Typed Electrode for a Fiber Supercapacitor (FSC)
Yeonggwon Kim, Hyung Woo Lee
J Powder Mater. 2025;32(1):30-36.   Published online February 28, 2025
DOI: https://doi.org/10.4150/jpm.2024.00416
  • 797 View
  • 21 Download
AbstractAbstract PDF
Fiber supercapacitors have attracted significant interest as potential textile energy storage devices due to their remarkable flexibility and rapid charge/discharge capabilities. This study describes the fabrication of a composite fiber supercapacitor (FSC) electrode through a multi-shell architecture, featuring layers of carbon nanotube (CNT) conductive shells and MnO₂ nanoparticle active shells. The number of layers was adjusted to assess their impact on FSC energy storage performance. Increasing the number of shells reduced electrode resistance and enhanced pseudocapacitive characteristics. Compared to the MnS@1 electrode, the MnS@5 electrode exhibited a high areal capacitance of 301.2 mF/cm², a 411% increase, but showed a higher charge transfer resistance (RCT) of 701.6 Ω. This is attributed to reduced ion diffusion and charge transfer ability resulting from the thicker multi-shell configuration. These results indicate that fine-tuning the quantity of shells is crucial for achieving an optimal balance between energy storage efficiency and stability.
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[Korean]
Development of Highly Transparent and Thermo-Shielding Flexible Film via Colloidal ITO Nanocrystals
Hyoin Bae, Hyeyeon Jung, Juna Lee, Dahye Shin, Sungyeon Heo
J Powder Mater. 2024;31(6):508-512.   Published online December 31, 2024
DOI: https://doi.org/10.4150/jpm.2024.00423
  • 712 View
  • 15 Download
AbstractAbstract PDF
Infrared radiation accounts for approximately 50% of the solar spectrum. Specifically, the near-infrared (NIR) spectrum, ranging from 760 nm to 2500 nm, is primarily responsible for solar heat gain, increasing indoor temperatures and reducing heating and cooling efficiency. To address this issue, we developed a highly transparent thermo-shielding flexible film that maintains a high transmittance of the visible region (T = 80%) while reducing the transmittance of the NIR region (T ≈ 0%). NIR-absorbing indium tin oxide (ITO) nanocrystals were coated onto polyethylene terephthalate (PET) films, and both films were sandwiched to improve the NIR absorption properties and protect the nanocrystal film layer. The fabricated films were applied to a model house and decreased the indoor temperature by approximately 8°C. Our study demonstrates that energy consumption can be reduced by ITO nanocrystal-coated flexible films, with potential implications for the smart window and mobility markets.
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[English]
Design of Conductive Inks Containing Carbon Black and Silver Nanowires for Patternable Screen-Printing on Fabrics
Seokhwan Kim, Geumseong Lee, Jinwoo Park, Dahye Shin, Ki-Il Park, Kyoung Jin Jung, Yuho Min
J Powder Mater. 2024;31(6):500-507.   Published online December 31, 2024
DOI: https://doi.org/10.4150/jpm.2024.00409
  • 1,576 View
  • 43 Download
  • 1 Citations
AbstractAbstract PDF
This study developed conductive inks composed of carbon black (CB) and silver nanowires (Ag NWs) for cost-effective screen-printing on fabrics. The Ag NW density within the CB matrix was precisely controlled, achieving tunable electrical conductivity with minimal Ag NW usage. The resulting inks were successfully patterned into shapes such as square grids and circles on textile surfaces, demonstrating excellent conductivity and fidelity. Adding 19.9 wt% Ag NWs reduced sheet resistance by ~92% compared to CB-only inks, highlighting the effectiveness and potential of this hybrid approach for cost-effective, high-performance textile-based electronics. The one-dimensional morphology of Ag NWs facilitated the formation of conductive percolation networks, creating efficient electron pathways within the CB matrix even at low loadings. This work advances the field of CB-based conductive inks and provides a scalable and practical method for producing functional, patterned electronic textiles.

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  • Multifunctional Screen-Printed Conductive Inks: Design Principles, Performance Challenges, and Application Horizons
    Nahid Islam, Manisha Das, Bashir Ahmed Johan, Syed Shaheen Shah, Atif Saeed Alzahrani, Md. Abdul Aziz
    ACS Applied Electronic Materials.2025; 7(16): 7503.     CrossRef
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[Korean]
Inter-laminar Strength of NITE-SiC/SiC Composites With Various Fiber Reinforcing Architecture
Jong-il Kim
J Powder Mater. 2024;31(5):437-444.   Published online October 31, 2024
DOI: https://doi.org/10.4150/jpm.2024.00248
  • 645 View
  • 9 Download
AbstractAbstract PDF
The mechanical performance of SiC/SiC composites is significantly influenced by the architecture of fiber reinforcement. Among the various fabrication methods, the nano-powder infiltration transition/eutectic (NITE) process is a promising technique that is capable of achieving a dense and stoichiometric SiC matrix. The reinforcement architecture, such as cross-ply (CP) or woven prepreg (WP), is determined during the preform stage of the NITE process, which is crucial in determining the mechanical properties of SiC/SiC composites. In this study, the tensile test and double notch shear (DNS) test were conducted using NITE-SiC/SiC composites to investigate the effect of the fiber reinforcing architecture on the fracture mechanism of SiC/SiC composites. The tensile strength and maximum shear strength of both CP and WP specimens were nearly identical. However, other mechanical properties, particularly those of CP specimens, exhibited significant variability. A comparison of fracture surfaces and load-displacement curve analyses from the DNS tests revealed that the cross points of the longitudinal or transverse fibers act as obstacles to both deformation and crack propagation. These obstacles were found to be more densely distributed in WP specimens than in CP specimens. The variability observed in the mechanical properties of CP specimens is likely due to size effects caused by the sparser distribution of these obstacles compared to the WP specimens.
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[Korean]
Preparation and Microstructural Characteristics of Ti Nanopowder by Ball Milling and Dehydrogenation of TiH2 Powder
Ji Young Kim, Eui Seon Lee, Ji Won Choi, Youngmin Kim, Sung-Tag Oh
J Powder Mater. 2024;31(4):324-328.   Published online August 30, 2024
DOI: https://doi.org/10.4150/jpm.2024.00199
  • 809 View
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AbstractAbstract PDF
This study analyzed the influence of ball size and process control agents on the refinement and dehydrogenation behavior of TiH2 powder. Powders milled using ZrO2 balls with diameters of 0.1 mm, 0.3 mm, and 0.3+0.5+1 mm exhibited a bimodal particle size distribution, of which the first mode had the smallest size of 0.23 μm for the 0.3 mm balls. Using ethanol and/or stearic acid as process control agents was effective in particle refinement. Thermogravimetric analysis showed that dehydrogenation of the milled powder started at a relatively low temperature compared to the raw powder, which is interpreted to have resulted from a decrease in particle size and an increase in defects. The dehydrogenation kinetics of the TiH2 powder were evaluated by the magnitude of peak shift with heating rates using thermogravimetric analysis. The activation energy of the dehydrogenation reaction, calculated from the slope of the Kissinger plot, was measured to be 228.6 kJ/mol for the raw powder and 194.5 kJ/mol for the milled powder. TEM analysis revealed that both the milled and dehydrogenated powders showed an angular shape with a size of about 200 nm.
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[Korean]
Effect of Hot Isostatic Pressing on the Stellite 6 Alloy prepared by Directed Energy Deposition
Joowon Suh, Jae Hyeon Koh, Young-Bum Chun, Young Do Kim, Jinsung Jang, Suk Hoon Kang, Heung Nam Han
J Powder Mater. 2024;31(2):152-162.   Published online April 30, 2024
DOI: https://doi.org/10.4150/jpm.2024.00066
  • 1,140 View
  • 32 Download
  • 1 Citations
AbstractAbstract PDF
The directed energy deposited (DED) alloys show higher hardness values than the welded alloys due to the finer microstructure following the high cooling rate. However, defects such as microcracks, pores, and the residual stress are remained within the DED alloy. These defects deteriorate the wear behavior so post-processing such as heat treatment and hot isostatic pressing (HIP) are applied to DED alloys to reduce the defects. HIP was chosen in this study because the high pressure and temperature uniformly reduced the defects. The HIP is processed at 1150oC under 100 MPa for 4 hours. After HIP, microcracks are disappeared and porosity is reduced by 86.9%. Carbides are spherodized due to the interdiffusion of Cr and C between the dendrite and interdendrite region. After HIP, the nanohardness (GPa) of carbides increased from 11.1 to 12, and the Co matrix decreased from 8.8 to 7.9. Vickers hardness (HV) decreased by 18.9 % after HIP. The dislocation density (10-2/m2) decreased from 7.34 to 0.34 and the residual stress (MPa) changed from tensile 79 to a compressive -246 by HIP. This study indicates that HIP is effective in reducing defects, and the HIP DED Stellite 6 exhibits a higher HV than welded Stellite 6.

Citations

Citations to this article as recorded by  
  • The Recycling Process and Powderization Technology of Stellite 6 Scrap: A Thermodynamic and Heat Transfer Analysis
    YongKwan Lee, Hyun-chul Kim, Myungsuk Kim, Soong Ju Oh, Kyoungtae Park, JaeJin Sim
    Journal of Powder Materials.2025; 32(4): 330.     CrossRef
Review Paper
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[English]
Eco-Friendly Powder and Particles-Based Triboelectric Energy Harvesters
Rayyan Ali Shaukat, Jihun Choi, Chang Kyu Jeong
J Powder Mater. 2023;30(6):528-535.   Published online December 1, 2023
DOI: https://doi.org/10.4150/KPMI.2023.30.6.528
  • 1,555 View
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  • 2 Citations
AbstractAbstract PDF

Since their initial development in 2012, triboelectric nanogenerators (TENGs) have gained popularity worldwide as a desired option for harnessing energy. The urgent demand for TENGs is attributed to their novel structural design, low cost, and use of large-scale materials. The output performance of a TENG depends on the surface charge density of the friction layers. Several recycled and biowaste materials have been explored as friction layers to enhance the output performance of TENGs. Natural and oceanic biomaterials have also been investigated as alternatives for improving the performance of TENG devices. Moreover, structural innovations have been made in TENGs to develop highly efficient devices. This review summarizes the recent developments in recycling and biowaste materials for TENG devices. The potential of natural and oceanic biowaste materials is also discussed. Finally, future outlooks for the structural developments in TENG devices are presented.

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  • Fabrication and Characterization of a Flexible Polyurethane-Based Triboelectric Nanogenerator for a Harvesting Energy System
    Saba Ejaz, Imran Shah, Shahid Aziz, Gul Hassan, Ahmed Shuja, Muhammad Asif Khan, Dong-Won Jung
    Micromachines.2025; 16(2): 230.     CrossRef
  • Optimized Process and Mechanical and Electrical Analysis of Polyimide/Pb(Zr,Ti)O3-Based Flexible Piezoelectric Composites
    Junki Lee, Sang-il Yoon, Hyunseung Kim, Chang Kyu Jeong
    Journal of Powder Materials.2025; 32(1): 16.     CrossRef
Articles
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[Korean]
Fabrication of Flexible Energy Harvester Based on BaTiO3 Piezoelectric Nanotube Arrays
Seo Young Yoon, Cheol Min Kim, Bitna Bae, Yujin Na, Haksu Jang, Kwi-Il Park
J Powder Mater. 2023;30(6):521-527.   Published online December 1, 2023
DOI: https://doi.org/10.4150/KPMI.2023.30.6.521
  • 767 View
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  • 2 Citations
AbstractAbstract PDF

Piezoelectric technology, which converts mechanical energy into electrical energy, has recently attracted drawn considerable attention in the industry. Among the many kinds of piezoelectric materials, BaTiO3 nanotube arrays, which have outstanding uniformity and anisotropic orientation compared to nanowire-based arrays, can be fabricated using a simple synthesis process. In this study, we developed a flexible piezoelectric energy harvester (f-PEH) based on a composite film with PVDF-coated BaTiO3 nanotube arrays through sequential anodization and hydrothermal synthesis processes. The f-PEH fabricated using the piezoelectric composite film exhibited excellent piezoelectric performance and high flexibility compared to the previously reported BaTiO3 nanotube array-based energy harvester. These results demonstrate the possibility for widely application with high performance by our advanced f-PEH technique based on BaTiO3 nanotube arrays.

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  • Flexible Thermoelectric Energy Harvester with Stacked Structure of Thermoelectric Composite Films Made of PVDF and Bi2Te3-Based Particles
    Da Eun Shin, Nagamalleswara Rao Alluri, Kwi-Il Park
    ACS Applied Energy Materials.2024; 7(19): 8288.     CrossRef
  • CoFe2O4-BaTiO3 core-shell-embedded flexible polymer composite as an efficient magnetoelectric energy harvester
    Bitna Bae, Nagamalleswara Rao Alluri, Cheol Min Kim, Jungho Ryu, Gwang Hyeon Kim, Hyeon Jun Park, Changyeon Baek, Min-Ku Lee, Gyoung-Ja Lee, Geon-Tae Hwang, Kwi-Il Park
    Materials Today Physics.2024; 48: 101567.     CrossRef
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[Korean]
Fabrication of Nanowire by Electrospinning Process Using Nickel Oxide Particle Recovered from MLCC
Haein Shin, Jongwon Bae, Minsu Kang, Kun-Jae Lee
J Powder Mater. 2023;30(6):502-508.   Published online December 1, 2023
DOI: https://doi.org/10.4150/KPMI.2023.30.6.502
  • 547 View
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AbstractAbstract PDF

With the increasing demand for electronic products, the amount of multilayer ceramic capacitor (MLCC) waste has also increased. Recycling technology has recently gained attention because it can simultaneously address raw material supply and waste disposal issues. However, research on recovering valuable metals from MLCCs and converting the recovered metals into high-value-added materials remains insufficient. Herein, we describe an electrospinning (E-spinning) process to recover nickel from MLCCs and modulate the morphology of the recovered nickel oxide particles. The nickel oxalate powder was recovered using organic acid leaching and precipitation. Nickel oxide nanoparticles were prepared via heat treatment and ultrasonic milling. A mixture of nickel oxide particles and polyvinylpyrrolidone (PVP) was used as the E-spinning solution. A PVP/NiO nanowire composite was fabricated via Espinning, and a nickel oxide nanowire with a network structure was manufactured through calcination. The nanowire diameters and morphologies are discussed based on the nickel oxide content in the E-spinning solution.

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[Korean]
Preparation and Evaluation of Ketoconazole-loaded Solid-SNEDDS (Self-Nanoemulsifying Drug Delivery System) using Various Solidification Carriers
Da Young Song, Kyeong Soo Kim
J Powder Mater. 2023;30(6):493-501.   Published online December 1, 2023
DOI: https://doi.org/10.4150/KPMI.2023.30.6.493
  • 777 View
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AbstractAbstract PDF

This study aimed to develop a solid self-nanoemulsifying drug delivery system (solid-SNEDDS) to enhance the formulation of ketoconazole (KTZ), a BCS Class II drug with poor solubility. Ketoconazole, which is insoluble above pH 3, requires solubilization for effective delivery. This SNEDDS comprises oil, surfactant, and co-surfactant, which spontaneously emulsify in the gastrointestinal tract environment to form nanoemulsions with droplet sizes less than 100 nm. The optimal SNE-vehicle composition of oleic acid, TPGS, and PEG 400 at a 10:80:10 weight ratio was determined based on the smallest droplet size achieved. This composition was used to prepare liquid SNEDDS containing ketoconazole. The droplet size and polydispersity index (PDI) of the resulting liquid SNEDDS were analyzed. Subsequently, solid-SNEDDS was fabricated using a spray-drying method with solidifying carriers such as silicon dioxide, crospovidone, and magnesium alumetasilicate. The physicochemical properties of the solid-SNEDDS were characterized by scanning electron microscopy and powder X-ray diffraction, and its solubility, droplet size, and PDI were evaluated. In particular, the solid-SNEDDS containing ketoconazole and crospovidone in a 2:1 weight ratio exhibited significantly enhanced solubility, highlighting its potential for improved medication adherence and dissolution rates.

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[Korean]
Irradiation Hardening Property of Inconel 718 Alloy produced by Selective Laser Melting
Joowon Suh, Sangyeob Lim, Hyung-Ha Jin, Young-Bum Chun, Suk Hoon Kang, Heung Nam Han
J Powder Mater. 2023;30(5):431-435.   Published online October 1, 2023
DOI: https://doi.org/10.4150/KPMI.2023.30.5.431
  • 886 View
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  • 1 Citations
AbstractAbstract PDF

An irradiation hardening of Inconel 718 produced by selective laser melting (SLM) was studied based on the microstructural observation and mechanical behavior. Ion irradiation for emulating neutron irradiation has been proposed owing to advantages such as low radiation emission and short experimental periods. To prevent softening caused by the dissolution of γ' and γ'' precipitates due to irradiation, only solution annealing (SA) was performed. SLM SA Inconel 718 specimen was ion irradiated to demonstrate the difference in microstructure and mechanical properties between the irradiated and non-irradiated specimens. After exposing specimens to Fe3+ ions irradiation up to 100 dpa (displacement per atom) at an ambient temperature, the hardness of irradiated specimens was measured by nanoindentation as a function of depth. The depth distribution profile of Fe3+ and dpa were calculated by the Monte Carlo SRIM (Stopping and Range of Ions in Matter)-2013 code under the assumption of the displacement threshold energy of 40 eV. A transmission electron microscope was utilized to observe the formation of irradiation defects such as dislocation loops. This study reveals that the Frank partial dislocation loops induce irradiation hardening of SLM SA Inconel 718 specimens.

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  • A Parametric Study on the L-PBF Process of an AlSi10Mg Alloy for High-Speed Productivity of Automotive Prototype Parts
    Yeonha Chang, Hyomoon Joo, Wanghyun Yong, Yeongcheol Jo, Seongjin Kim, Hanjae Kim, Yeon Woo Kim, Kyung Tae Kim, Jeong Min Park
    Journal of Powder Materials.2024; 31(5): 390.     CrossRef
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[Korean]
Fabrication of Polymer Composite with Enhanced Insulation and Mechanical Properties using Aluminum Borate Nanowhiskers
Junhyeok Choi, Sangin Lee, Kiho Song, Taekyung Kim, Changui Ahn
J Powder Mater. 2023;30(4):356-362.   Published online August 1, 2023
DOI: https://doi.org/10.4150/KPMI.2023.30.4.356
  • 778 View
  • 2 Download
  • 1 Citations
AbstractAbstract PDF

Inorganic-organic composites find extensive application in various fields, including electronic devices and light-emitting diodes. Notably, encapsulation technologies are employed to shield electronic devices (such as printed circuit boards and batteries) from stress and moisture exposure while maintaining electrical insulation. Polymer composites can be used as encapsulation materials because of their controllable mechanical and electrical properties. In this study, we propose a polymer composite that provides good electrical insulation and enhanced mechanical properties. This is achieved by using aluminum borate nanowhiskers (ABOw), which are fabricated using a facile synthesis method. The ABOw fillers are created via a hydrothermal method using aluminum chloride and boric acid. We confirm that the synthesis occurs in various morphologies based on the molar ratio. Specifically, nanowhiskers are synthesized at a molar ratio of 1:3 and used as fillers in the composite. The fabricated ABOw/epoxy composites exhibit a 48.5% enhancement in mechanical properties, similar to those of pure epoxy, while maintaining good electrical insulation.

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  • Fabrication of Al18B4O33 Spherical Powder with Increased Fluidity via Control of B2O3 Particle Size and Distribution
    Kiho Song, Sang in Lee, Hyunseung Song, Changui Ahn
    Journal of Powder Materials.2024; 31(6): 513.     CrossRef
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[Korean]
Capacitance Enhancement and Evaluation of Gold-Deposited Carbon Nanotube Film Ion-Selective Electrode
Do Youn Kim, Hanbyeol Son, Hyo-Ryoung Lim
J Powder Mater. 2023;30(4):310-317.   Published online August 1, 2023
DOI: https://doi.org/10.4150/KPMI.2023.30.4.310
  • 719 View
  • 7 Download
AbstractAbstract PDF

Small-film-type ion sensors are garnering considerable interest in the fields of wearable healthcare and home-based monitoring systems. The performance of these sensors primarily relies on electrode capacitance, often employing nanocomposite materials composed of nano- and sub-micrometer particles. Traditional techniques for enhancing capacitance involve the creation of nanoparticles on film electrodes, which require cost-intensive and complex chemical synthesis processes, followed by additional coating optimization. In this study, we introduce a simple one-step electrochemical method for fabricating gold nanoparticles on a carbon nanotube (Au NP–CNT) electrode surface through cyclic voltammetry deposition. Furthermore, we assess the improvement in capacitance by distinguishing between the electrical double-layer capacitance and diffusion-controlled capacitance, thereby clarifying the principles underpinning the material design. The Au NP–CNT electrode maintains its stability and sensitivity for up to 50 d, signifying its potential for advanced ion sensing. Additionally, integration with a mobile wireless data system highlights the versatility of the sensor for health applications.

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[Korean]
Fabrication and Evaluation of Colloidal Silica Containing Powders for Solid Self-emulsifying Drug Delivery System of Poorly Water Soluble Rivaroxaban
Sung Giu Jin
J Powder Mater. 2023;30(4):305-309.   Published online August 1, 2023
DOI: https://doi.org/10.4150/KPMI.2023.30.4.305
  • 635 View
  • 2 Download
AbstractAbstract PDF

This study aims to prepare a colloidal silica-containing powder to enhance the solubility and dissolution rate of rivaroxaban using a self-nanoemulsifying drug delivery system (SNEDDS). We investigate the impact of colloidal silica on a nanoemulsion system for preparing powdered SNEDDS. The liquid SNEDDS comprises 30/20/50 (w/w/w) Peceol/ Cremophor RH40/Tween 80, which results in the formation of the smallest droplets. Three powdered SNEDDS formulations are prepared by suspending the liquid SNEDDS formulation using colloidal silica and spray drying. The powdered SNEDDS prepared with liquid SNEDDS and colloidal silica at a ratio of 1/0.5 (w/w) exhibits the highest water solubility (0.94 ± 0.62 vs. 26.70 ± 1.81 μg/mL) and dissolution rate (38.4 ± 3.6 vs. 85.5 ± 3.4%, 45 min) when compared to the drug alone. Morphologically, the liquid SNEDDS is adsorbed onto colloidal silica and forms smaller particles. In conclusion, an SNEDDS containing rivaroxaban, prepared using colloidal silica, facilitates the creation of a nanoemulsion and enhances the water solubility of rivaroxaban. Accordingly, this technology holds significant potential for commercialization.

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[Korean]
Size Control of Iron Oxide (Fe3O4) Nanoclusters according to Reaction Factors and Consequent Change in Their Magnetic Attraction
Sanghoon Lee, Arim Byun, Jin-sil Choi
J Powder Mater. 2023;30(4):297-304.   Published online August 1, 2023
DOI: https://doi.org/10.4150/KPMI.2023.30.4.297
  • 718 View
  • 11 Download
  • 1 Citations
AbstractAbstract PDF

Iron oxide (Fe2O3) nanoclusters exhibit significant potential in the biomedical and pharmaceutical fields due to their strong magnetic properties, stability in solutions, and compatibility with living systems. They excel in magnetic separation processes, displaying high responsiveness to external magnetic fields. In contrast to conventional Fe2O3 nanoparticles that can aggregate in aqueous solutions due to their ferrimagnetic properties, these nanoclusters, composed of multiple nanoparticles, maintain their magnetic traits even when scaled to hundreds of nanometers. In this study, we develop a simple method using solvothermal synthesis to precisely control the size of nanoclusters. By adjusting precursor materials and reducing agents, we successfully control the particle sizes within the range of 90 to 420 nm. Our study not only enhances the understanding of nanocluster creation but also offers ways to improve their properties for applications such as magnetic separation. This is supported by our experimental results highlighting their size-dependent magnetic response in water. This study has the potential to advance both the knowledge and practical utilization of Fe2O3 nanoclusters in various applications.

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  • Enzymatic properties of iron oxide nanoclusters and their application as a colorimetric glucose detection probe
    Dahyun Bae, Minhee Kim, Jin-sil Choi
    RSC Advances.2025; 15(6): 4573.     CrossRef
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[Korean]
Enhancement of Thermoelectric Performance in Spark Plasma Sintered p-Type Bi0.5Sb1.5Te3.0 Compound via Hot Isostatic Pressing (HIP) Induced Reduction of Lattice Thermal Conductivity
Soo-Ho Jung, Ye Jin Woo, Kyung Tae Kim, Seungki Jo
J Powder Mater. 2023;30(2):123-129.   Published online April 1, 2023
DOI: https://doi.org/10.4150/KPMI.2023.30.2.123
  • 1,365 View
  • 8 Download
  • 4 Citations
AbstractAbstract PDF

High-temperature and high-pressure post-processing applied to sintered thermoelectric materials can create nanoscale defects, thereby enhancing their thermoelectric performance. Here, we investigate the effect of hot isostatic pressing (HIP) as a post-processing treatment on the thermoelectric properties of p-type Bi0.5Sb1.5Te3.0 compounds sintered via spark plasma sintering. The sample post-processed via HIP maintains its electronic transport properties despite the reduced microstructural texturing. Moreover, lattice thermal conductivity is significantly reduced owing to activated phonon scattering, which can be attributed to the nanoscale defects created during HIP, resulting in an ~18% increase in peak zT value, which reaches ~1.43 at 100°C. This study validates that HIP enhances the thermoelectric performance by controlling the thermal transport without having any detrimental effects on the electronic transport properties of thermoelectric materials.

Citations

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  • Enhanced Electrical Properties of 3D Printed Bi2Te3-Based Thermoelectric Materials via Hot Isostatic Pressing
    Seungki Jo
    Ceramist.2025; 28(1): 126.     CrossRef
  • Exploring Thermoelectric Transport Properties and Band Parameters of n-Type Bi2-xSbxTe3 Compounds Using the Single Parabolic Band Model
    Linh Ba Vu, Soo-ho Jung, Jinhee Bae, Jong Min Park, Kyung Tae Kim, Injoon Son, Seungki Jo
    journal of Korean Powder Metallurgy Institute.2024; 31(2): 119.     CrossRef
  • Investigation of the Thermal-to-Electrical Properties of Transition Metal-Sb Alloys Synthesized for Thermoelectric Applications
    Jong Min Park, Seungki Jo, Sooho Jung, Jinhee Bae, Linh Ba Vu, Kwi-Il Park, Kyung Tae Kim
    journal of Korean Powder Metallurgy Institute.2024; 31(3): 236.     CrossRef
  • Enhancing Electrical Properties of N-type Bismuth Telluride Alloys through Graphene Oxide Incorporation in Extrusion 3D Printing
    Jinhee Bae, Seungki Jo, Kyung Tae Kim
    journal of Korean Powder Metallurgy Institute.2023; 30(4): 318.     CrossRef
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[Korean]
A Study on Mechano-chemical Ball Milling Process for Fabricating Tungsten Disulfide Nanosheets
Seulgi Kim, Yunhee Ahn, Dongju Lee
J Powder Mater. 2022;29(5):376-381.   Published online October 1, 2022
DOI: https://doi.org/10.4150/KPMI.2022.29.5.376
  • 426 View
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AbstractAbstract PDF

Tungsten disulfide (WS2) nanosheets have attracted considerable attention because of their unique optical and electrical properties. Several methods for fabrication of WS2 nanosheets have been developed. However, methods for mass production of high-quality WS2 nanosheets remain challenging. In this study, WS2 nanosheets were fabricated using mechano-chemical ball milling based on the synergetic effects of chemical intercalation and mechanical exfoliation. The ball-milling time was set as a variable for the optimized fabricating process of WS2 nanosheets. Under the optimized conditions, the WS2 nanosheets had lateral sizes of 500–600 nm with either a monolayer or bilayer. They also exhibited high crystallinity in the 2H semiconducting phase. Thus, the proposed method can be applied to the exfoliation of other transition metal dichalcogenides using suitable chemical intercalants. It can also be used with highperformance WS2-based photodiodes and transistors used in practical semiconductor applications.

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[Korean]
Aqueous Synthesis and Luminescent Characteristics of Cu:ZnSe Quantum Dots by Internal Doping Method
Geum Ji Back, Hyun Seon Hong
J Powder Mater. 2022;29(5):370-375.   Published online October 1, 2022
DOI: https://doi.org/10.4150/KPMI.2022.29.5.370
  • 712 View
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AbstractAbstract PDF

Cu-doped ZnSe quantum dots were successfully synthesized in an aqueous solution using an internal doping method. The effects of ligand type, CuSe synthesis temperature, and heating time on Cu-doped ZnSe synthesis were systematically investigated. Of MPA, GSH, TGA, and NAC used as ligands, MPA was the optimal ligand as determined by PL spectrum analysis. In addition, the emission wavelength was found to depend on the synthesis temperature of the internal doping core of CuSe. As the temperature increased, the doping of Cu2+ was enhanced, and the emission wavelength band was redshifted; accordingly, the emission peaks moved from blue to green (up to 550 nm). Thus, the synthesis of Cu:ZnSe using internal doping in aqueous solutions is a potential method for ecomanufacturing of colortuned ZnSe quantum dots for display applications.

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  • Synthesis and luminescence characteristics of manganese-doped ZnSe quantum dots synthesized in aqueous solution through internal doping
    Hyun Seon Hong, Yerin Kim, Jea Hyung Kim, Hyeon Seon Ryu, Dahye Song
    Journal of the Korean Ceramic Society.2025; 62(3): 472.     CrossRef
Review Paper
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[Korean]
Recent Studies on Performance Enhancement of Polycrystal SnSe Thermoelectric Materials
Myeong Jun Jung, Byung Joon Choi
J Powder Mater. 2022;29(2):152-158.   Published online April 1, 2022
DOI: https://doi.org/10.4150/KPMI.2022.29.2.152
  • 873 View
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  • 1 Citations
AbstractAbstract PDF

Thermoelectric materials can reversely convert heat and electricity into each other; therefore, they can be very useful for energy harvesting from heat waste. Among many thermoelectrical materials, SnSe exhibits outstanding thermoelectric performance along the particular direction of a single crystal. However, single-crystal SnSe has poor mechanical properties and thus it is difficult to apply for mass production. Therefore, polycrystalline SnSe materials may be used to replace single-crystal SnSe by overcoming its inferior thermoelectric performance owing to surface oxidation. Considerable efforts are currently focused on enhancing the thermoelectric performance of polycrystalline SnSe. In this study, we briefly review various enhancement methods for SnSe thermoelectric materials, including doping, texturing, and nano-structuring. Finally, we discuss the future prospects of SnSe thermoelectric powder materials.

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  • The Mechanism Behind the High zT of SnSe2 Added SnSe at High Temperatures
    JunSu Kim, Seong-Mee Hwang, Hyunjin Park, Yinglu Tang, Won-Seon Seo, Chae Woo Ryu, Heesun Yang, Weon Ho Shin, Hyun-Sik Kim
    Korean Journal of Metals and Materials.2023; 61(11): 857.     CrossRef
Article
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[Korean]
Effect of Process Stopping and Restarting on the Microstructure and Local Property of 316L Stainless Steel Manufactured by Selective Laser Melting Process
Hyunjin Joo, Jeongmin Woo, Yongho Sohn, Kee-Ahn Lee
J Powder Mater. 2022;29(1):1-7.   Published online February 1, 2022
DOI: https://doi.org/10.4150/KPMI.2022.29.1.1
  • 633 View
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AbstractAbstract PDF

This study investigates the effect of process stopping and restarting on the microstructure and local nanoindentation properties of 316L stainless steel manufactured via selective laser melting (SLM). We find that stopping the SLM process midway, exposing the substrate to air having an oxygen concentration of 22% or more for 12 h, and subsequently restarting the process, makes little difference to the density of the restarted area (~ 99.8%) as compared to the previously melted area of the substrate below. While the microstructure and pore distribution near the stop/restart area changes, this modified process does not induce the development of unusual features, such as an inhomogeneous microstructure or irregular pore distribution in the substrate. An analysis of the stiffness and hardness values of the nano-indented steel also reveals very little change at the joint of the stop/restart area. Further, we discuss the possible and effective follow-up actions of stopping and subsequently restarting the SLM process.

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  • On the Fabrication of Functionally Graded Prototypes with Laser Powder Bed Fusion from Reused Ni-625 and 17-4 PH Stainless Steel Powder
    Bharat Kalia, Rupinder Singh, B. S. Pabla
    Journal of Materials Engineering and Performance.2025;[Epub]     CrossRef
  • Additive Manufacturing of SS316L/IN718 Bimetallic Structure via Laser Powder Bed Fusion
    Asif Mahmud, Nicolas Ayers, Thinh Huynh, Yongho Sohn
    Materials.2023; 16(19): 6527.     CrossRef
Review Paper
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[Korean]
Controlling the Heat Generation Capability of Iron Oxide-Base Nanoparticles
Jin-sil Choi
J Korean Powder Metall Inst. 2021;28(6):518-526.   Published online December 1, 2021
DOI: https://doi.org/10.4150/KPMI.2021.28.6.518
  • 513 View
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AbstractAbstract PDF

This review summarizes the recent progress in iron-oxide-based heat generators. Cancer treatment using magnetic nanoparticles as a heat generator, termed magnetic fluid hyperthermia, is a promising noninvasive approach that has gained significant interest. Most previous studies on improving the hyperthermia effect have focused on the construction of dopant-containing iron oxides. However, their applications in a clinical application can be limited due to extra dopants, and pure iron oxide is the only inorganic material approved by the Food and Drug Administration (FDA). Several factors that influence the heat generation capability of iron-oxide-based nanoparticles are summarized by reviewing recent studies on hyperthermia agents. Thus, our paper will provide the guideline for developing pure iron oxide-based heat generators with high heat dissipation capabilities.

Article
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[Korean]
Preparation of CoFe2O4 Nanoparticle Decorated on Electrospun Carbon Nanofiber Composite Electrodes for Supercapacitors
Hyewon Hwang, Seoyeon Yuk, Minsik Jung, Dongju Lee
J Korean Powder Metall Inst. 2021;28(6):470-477.   Published online December 1, 2021
DOI: https://doi.org/10.4150/KPMI.2021.28.6.470
  • 570 View
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AbstractAbstract PDF

Energy storage systems should address issues such as power fluctuations and rapid charge-discharge; to meet this requirement, CoFe2O4 (CFO) spinel nanoparticles with a suitable electrical conductivity and various redox states are synthesized and used as electrode materials for supercapacitors. In particular, CFO electrodes combined with carbon nanofibers (CNFs) can provide long-term cycling stability by fabricating binder-free three-dimensional electrodes. In this study, CFO-decorated CNFs are prepared by electrospinning and a low-cost hydrothermal method. The effects of heat treatment, such as the activation of CNFs (ACNFs) and calcination of CFO-decorated CNFs (C-CFO/ACNFs), are investigated. The C-CFO/ACNF electrode exhibits a high specific capacitance of 142.9 F/g at a scan rate of 5 mV/s and superior rate capability of 77.6% capacitance retention at a high scan rate of 500 mV/s. This electrode also achieves the lowest charge transfer resistance of 0.0063 Ω and excellent cycling stability (93.5% retention after 5,000 cycles) because of the improved ion conductivity by pathway formation and structural stability. The results of our work are expected to open a new route for manufacturing hybrid capacitor electrodes containing the C-CFO/ACNF electrode that can be easily prepared with a low-cost and simple process with enhanced electrochemical performance.

Review Paper
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[Korean]
Synthesis and Application of Magnetoplasmonic Nanoparticles
Sejeong Park, Siyeong Hwang, Seonghwan Jung, Juyong Gwak, Jaebeom Lee
J Korean Powder Metall Inst. 2021;28(5):429-434.   Published online October 1, 2021
DOI: https://doi.org/10.4150/KPMI.2021.28.5.429
  • 503 View
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AbstractAbstract PDF

Magnetic nanoparticles have a significant impact on the development of basic sciences and nanomedical, electronic, optical, and biotech industries. The development of magnetic structures with size homogeneity, magnetization, and particle dispersibility due to high-quality process development can broaden their utilization for separation analysis, structural color optics using surface modification, and energy/catalysts. In addition, magnetic nanoparticles simultaneously exhibit two properties: magnetic and plasmon resonance, which can be self-assembled and can improve signal sensitivity through plasmon resonance. This paper reports typical examples of the synthesis and properties of various magnetic nanoparticles, especially magnetoplasmonic nanoparticles developed in our laboratory over the past decade, and their optical, electrochemical, energy/catalytic, and bio-applications. In addition, the future value of magnetoplasmonic nanoparticles can be reevaluated by comparing them with that reported in the literature.

Articles
Article image
[Korean]
Austenite Stability and Mechanical Properties of Nanocrystalline FeNiCrMoMnSiC Alloy Fabricated by Spark Plasma Sintering
Jungbin Park, Junhyub Jeon, Namhyuk Seo, Gwanghun Kim, Seung Bae Son, Seok-Jae Lee
J Korean Powder Metall Inst. 2021;28(4):336-341.   Published online August 1, 2021
DOI: https://doi.org/10.4150/KPMI.2021.28.4.336
  • 737 View
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  • 1 Citations
AbstractAbstract PDF

In this study, a nanocrystalline FeNiCrMoMnSiC alloy was fabricated, and its austenite stability, microstructure, and mechanical properties were investigated. A sintered FeNiCrMoMnSiC alloy sample with nanosized crystal was obtained by high-energy ball milling and spark plasma sintering. The sintering behavior was investigated by measuring the displacement according to the temperature of the sintered body. Through microstructural analysis, it was confirmed that a compact sintered body with few pores was produced, and cementite was formed. The stability of the austenite phase in the sintered samples was evaluated by X-ray diffraction analysis and electron backscatter diffraction. Results revealed a measured value of 51.6% and that the alloy had seven times more austenite stability than AISI 4340 wrought steel. The hardness of the sintered alloy was 60.4 HRC, which was up to 2.4 times higher than that of wrought steel.

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  • Microstructure and mechanical behavior of AISI 4340 steel fabricated via spark plasma sintering and post-heat treatment
    Jungbin Park, Junhyub Jeon, Namhyuk Seo, Singon Kang, Seung Bae Son, Seok-Jae Lee, Jae-Gil Jung
    Materials Science and Engineering: A.2023; 862: 144433.     CrossRef
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[Korean]
A Study on the Microstructure and Magnetic Properties of Fe83.2Si5.33-0.33xB10.67-0.67xPxCu0.8 Nanocrystalline Soft Magnetic Alloys with varying P Content
Hyun Ah Im, Kyoung-Hoon Bae, Yeong gyun Nam, Subong An, Sangsun Yang, Yong-Jin Kim, Jung Woo Lee, Jae Won Jeong
J Korean Powder Metall Inst. 2021;28(4):293-300.   Published online August 1, 2021
DOI: https://doi.org/10.4150/KPMI.2021.28.4.293
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AbstractAbstract PDF

We investigate the effect of phosphorous content on the microstructure and magnetic properties of Fe83.2Si5.33-0.33xB10.67-0.67xPxCu0.8 (x = 1–4 at.%) nanocrystalline soft magnetic alloys. The simultaneous addition of Cu and P to nanocrystalline alloys reportedly decreases the nanocrystalline size significantly, to 10–20 nm. In the P-containing nanocrystalline alloy, P atoms are distributed in an amorphous residual matrix, which suppresses grain growth, increases permeability, and decreases coercivity. In this study, nanocrystalline ribbons with a composition of Fe83.2Si5.33-0.33xB10.67- 0.67xPxCu0.8 (x = 1–4 at.%) are fabricated by rapid quenching melt-spinning and thermal annealing. It is demonstrated that the addition of a small amount of P to the alloy improves the glass-forming ability and increases the resistance to undesirable Fex(B,P) crystallization. Among the alloys investigated in this work, an Fe83.2Si5B10P1Cu0.8 nanocrystalline ribbon annealed at 460°C exhibits excellent soft-magnetic properties including low coercivity, low core loss, and high saturation magnetization. The uniform nanocrystallization of the Fe83.2Si5B10P1Cu0.8 alloy is confirmed by high-resolution transmission electron microscopy analysis.

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[Korean]
A Study on Morphology Control of (Ga1-xZnx)(N1-xOx) Nanofibers according to the Composition and Crystallinity of Oxide Nanofibers Synthesized by Electrospinning
Jeong Hyun Kim, Sung-Tag Oh, Young-In Lee
J Korean Powder Metall Inst. 2021;28(3):259-266.   Published online June 1, 2021
DOI: https://doi.org/10.4150/KPMI.2021.28.3.259
  • 497 View
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AbstractAbstract PDF

The (Ga1-xZnx)(N1-xOx) solid solution is attracting extensive attention for photocatalytic water splitting and wastewater treatment owing to its narrow and controllable band gap. To optimize the photocatalytic performance of the solid solution, the key points are to decrease its band gap and recombination rate. In this study, (Ga1-xZnx)(N1-xOx) nanofibers with various Zn fractions are prepared by electrospinning followed by calcination and nitridation. The effect of the composition and crystallinity of electrospun oxide nanofibers on the morphology and optical properties of the obtained solid-solution nanofibers are systematically investigated. The results show that the final shape of the (Ga1-xZnx) (N1-xOx) material is greatly affected by the crystallinity of the oxide nanofibers before nitridation. The photocatalytic properties of (Ga1-xZnx)(N1-xOx) with different Ga:Zn atomic ratios are investigated by studying the degradation of rhodamine B under visible light irradiation.

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  • Fabrication of Nanowire by Electrospinning Process Using Nickel Oxide Particle Recovered from MLCC
    Haein Shin, Jongwon Bae, Minsu Kang, Kun-Jae Lee
    journal of Korean Powder Metallurgy Institute.2023; 30(6): 502.     CrossRef
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[Korean]
Development of Aluminum Matrix Composites Containing Nano-carbon Materials
Jungjoon Kim, Daeyoung Kim, Hyunjoo Choi
J Korean Powder Metall Inst. 2021;28(3):253-258.   Published online June 1, 2021
DOI: https://doi.org/10.4150/KPMI.2021.28.3.253
  • 605 View
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AbstractAbstract PDF

There is increasing demand for the development of a new material with high strength, high stiffness, and good electrical conductivity that can be used for high-voltage direct current cables. In this study, we develop aluminumbased composites containing C60 fullerenes, carbon nanotubes, or graphene using a powder metallurgical route and evaluate their strength, stiffness, coefficient of thermal expansion, and electrical conductivity. By optimizing the process conditions, a material with a tensile strength of 800 MPa, an elastic modulus of 90 GPa, and an electrical conductivity of 40% IACS is obtained, which may replace iron-core cables. Furthermore, by designing the type and volume fraction of the reinforcement, a material with a tensile strength of 380 MPa, elastic modulus of 80 GPa, and electrical conductivity of 54% IACS is obtained, which may compete with AA 6201 aluminum alloys for use in all-aluminum conductor cables.

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  • Synergistic strengthening of aluminum with SiC by grain refinement and dispersion hardening
    Kanhu C. Nayak, Juyeon Han, Suwon Park, Miran Joo, Kon‐Bae Lee, Donghyun Bae, Hyunjoo Choi
    Journal of the American Ceramic Society.2023; 106(12): 7340.     CrossRef
  • Synergetic effect of milling speed and duration on particle morphology and mechanical properties of nanocrystalline Al matrix containing SiC
    K.C. Nayak, J.Y. Han, C.H. Jung, M.R. Joo, K.B. Lee, D.H. Bae, H.J. Choi
    Powder Metallurgy.2023; 66(5): 519.     CrossRef
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[Korean]
Effect of Hydrothermal Reaction Conditions on Piezoelectric Output Performance of One Dimensional BaTiO3 Nanotube Arrays
Jae Hoon Lee, Dong Yeol Hyeon, Dong Hun Heo, Kwi-Il Park
J Korean Powder Metall Inst. 2021;28(2):127-133.   Published online April 1, 2021
DOI: https://doi.org/10.4150/KPMI.2021.28.2.127
  • 821 View
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  • 2 Citations
AbstractAbstract PDF

One-dimensional (1D) piezoelectric nanostructures are attractive candidates for energy generation because of their excellent piezoelectric properties attributed to their high aspect ratios and large surface areas. Vertically grown BaTiO3 nanotube (NT) arrays on conducting substrates are intensively studied because they can be easily synthesized with excellent uniformity and anisotropic orientation. In this study, we demonstrate the synthesis of 1D BaTiO3 NT arrays on a conductive Ti substrate by electrochemical anodization and sequential hydrothermal reactions. Subsequently, we explore the effect of hydrothermal reaction conditions on the piezoelectric energy conversion efficiency of the BaTiO3 NT arrays. Vertically aligned TiO2 NT arrays, which act as the initial template, are converted into BaTiO3 NT arrays using hydrothermal reaction with various concentrations of the Ba source and reaction times. To validate the electrical output performance of the BaTiO3 NT arrays, we measure the electricity generated from each NT array packaged with a conductive metal foil and epoxy under mechanical pushings. The generated output voltage signals from the BaTiO3 NT arrays increase with increasing concentration of the Ba source and reaction time. These results provide a new strategy for fabricating advanced 1D piezoelectric nanostructures by demonstrating the correlation between hydrothermal reaction conditions and piezoelectric output performance.

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  • Optimized Process and Mechanical and Electrical Analysis of Polyimide/Pb(Zr,Ti)O3-Based Flexible Piezoelectric Composites
    Junki Lee, Sang-il Yoon, Hyunseung Kim, Chang Kyu Jeong
    Journal of Powder Materials.2025; 32(1): 16.     CrossRef
  • Fabrication of Flexible Energy Harvester Based on BaTiO3 Piezoelectric Nanotube Arrays
    Seo Young Yoon, Cheol Min Kim, Bitna Bae, Yujin Na, Haksu Jang, Kwi-Il Park
    journal of Korean Powder Metallurgy Institute.2023; 30(6): 521.     CrossRef
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[Korean]
Effects of Synthesis Conditions on Luminescence Characteristics of Glutathione Capped ZnSe Nano particles
Geum Ji Back, Ha Yeon Song, Min Seo Lee, Hyun Seon Hong
J Korean Powder Metall Inst. 2021;28(1):44-50.   Published online February 1, 2021
DOI: https://doi.org/10.4150/KPMI.2021.28.1.44
  • 954 View
  • 6 Download
  • 2 Citations
AbstractAbstract PDF

Zinc selenide (ZnSe) nanoparticles were synthesized in aqueous solution using glutathione (GSH) as a ligand. The influence of the ligand content, reaction temperature, and hydroxyl ion concentration (pH) on the fabrication of the ZnSe particles was investigated. The optical properties of the synthesized ZnSe particles were characterized using various analytical techniques. The nanoparticles absorbed UV-vis light in the range of 350-400 nm, which is shorter than the absorption wavelength of bulk ZnSe particles (460 nm). The lowest ligand concentration for achieving good light absorption and emission properties was 0.6 mmol. The reaction temperature had an impact on the emission properties; photoluminescence spectroscopic analysis showed that the photo-discharge characteristics were greatly enhanced at high temperatures. These discharge characteristics were also affected by the hydroxyl ion concentration in solution; at pH 13, sound emission characteristics were observed, even at a low temperature of 25°C. The manufactured nanoparticles showed excellent light absorption and emission properties, suggesting the possibility of fabricating ZnSe QDs in aqueous solutions at low temperatures.

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  • Green synthesis and luminescence characteristics of ZnSe-ZnS core-shell quantum dots
    Geum Ji Back, Ha Yeon Song, Min Seo Lee, Jaesik Yoon, Hyun Seon Hong
    Journal of Crystal Growth.2024; 626: 127475.     CrossRef
  • Effect of UV Irradiation on Optical Properties of Water-Based Synthetic Zinc Selenide Quantum Dots
    Geum Ji Back, Yu Jin Kang, I Ju Kang, Jeong Hyeon Lim, Hyun Seon Hong
    Korean Journal of Metals and Materials.2022; 60(2): 160.     CrossRef
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[English]
Features of Nickel Nanoparticles Structure Synthesized by the Spark Discharge Method
C. K. Rhee, A. D. Maksimov, I. V. Beketov, A. I. Medvedev, A. M. Murzakaev
J Korean Powder Metall Inst. 2020;27(6):464-467.   Published online December 1, 2020
DOI: https://doi.org/10.4150/KPMI.2020.27.6.464
  • 1,010 View
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  • 2 Citations
AbstractAbstract PDF

Nickel nanopowders are obtained by the spark discharge method, which is based on the evaporation of the electrode surface under the action of the discharge current, followed by vapor condensation and the formation of nanoparticles. Nickel electrodes with a purity of 99.99% are used to synthesize the nickel nanoparticles in the setup. Nitrogen is used as the carrier gas with a purity of 99.998%. XRD, TEM, and EDX analyses of the nanopowders are performed. Moreover, HRTEM images with measured interplanar spacings are obtained. In the nickel nanopowder samples, a phase of approximately 90 wt% with an expanded crystal lattice of 6.5% on average is found. The results indicate an unusual process of nickel nanoparticle formation when the spark discharge method is employed.

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  • Comparative Study of Spots and Craters Formed during Spark Discharge in Air on Electrodes Made of Different Metals
    A. D. Maksimov, E. I. Azarkevich, I. V. Beketov, D. S. Koleukh
    Bulletin of the Russian Academy of Sciences: Physics.2025; 89(10): 1941.     CrossRef
  • Comparative Analysis of Craters Formed on Cathode and Anode Spots of a Spark Discharge in Air on Iron Electrodes
    A. D. Maksimov, E. I. Azarkevich, I. V. Beketov, D. S. Koleukh
    Bulletin of the Russian Academy of Sciences: Physics.2023; 87(S2): S274.     CrossRef
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[English]
Interaction of Detonation Nanodiamonds with Hispidin
Changkyu Rhee, Whungwhoe Kim, Andrey E. Burov, Alexey P. Puzyr, Vladimir S. Bondar
J Korean Powder Metall Inst. 2020;27(6):458-463.   Published online December 1, 2020
DOI: https://doi.org/10.4150/KPMI.2020.27.6.458
  • 517 View
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AbstractAbstract PDF

Hispidin is a secondary metabolite found in numerous medicinal mushrooms that has attracted significant attention, owing to its distinct biological effects, including antioxidant, anti-inflammatory, antitumor, and cytoprotective properties. Experiments are being carried out to study the interaction of detonation nanodiamonds (DNDs) with synthetic and natural hispidin sourced from extracts of Pholiota sp. fungus. The bioluminescence method is used to determine the adsorption/ desorption properties of DNDs toward hispidin. It is found that hispidin forms strong conjugates with DNDs, and the use of various eluents does not result in a significant release of the adsorbed hispidin molecules. DND-bovine serum albumin (BSA) complex, where DNDs serve as a carrier for the protein and the latter acts as a hispidin sorbent, has been developed and applied in hispidin adsorption/desorption tests. The results support the use of the DNDs as a carrier for hispidin in medical applications. They also advocate the application of the DND-BSA complex for isolating the substance from fungal extracts.

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[English]
Fabrication and Characterization of Immiscible Fe-Cu Alloys using Electrical Explosion of Wire in Liquid
Chu Dac Phuc, Nguyen Minh Thuyet, Jin-Chun Kim
J Korean Powder Metall Inst. 2020;27(6):449-457.   Published online December 1, 2020
DOI: https://doi.org/10.4150/KPMI.2020.27.6.449
  • 1,161 View
  • 11 Download
  • 3 Citations
AbstractAbstract PDF

Iron and copper are practically immiscible in the equilibrium state, even though their atomic radii are similar. As non-equilibrium solid solutions, the metastable Fe-Cu alloys can be synthesized using special methods, such as rapid quenching, vapor deposition, sputtering, ion-beam mixing, and mechanical alloying. The complexity of these methods (multiple steps, low productivity, high cost, and non-eco-friendliness) is a hinderance for their industrial applications. Electrical explosion of wire (EEW) is a well-known and effective method for the synthesis of metallic and alloy nanoparticles, and fabrication using the EEW is a simple and economic process. Therefore, it can be potentially employed to circumvent this problem. In this work, we propose the synthesis of Fe-Cu nanoparticles using EEW in a suitable solution. The powder shape, size distribution, and alloying state are analyzed and discussed according to the conditions of the EEW.

Citations

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  • Identification of the reconstruction induced high-entropy spinel oxide nanosheets for boosting alkaline water oxygen evolution
    Xuexue Wang, Runqing Lu, Shanhe Gong, Shaokang Yang, Wenbo Wang, Zhongti Sun, Xiaozhen Zhang, Jun Liu, Xiaomeng Lv
    Chemical Engineering Journal.2025; 503: 158488.     CrossRef
  • Trends in bimetallic nanomaterials and methods for the removal of p-nitrophenol and its derivatives from wastewater
    M. S. Qatan, F. Arshad, M. Miskam, G. A. Naikoo
    International Journal of Environmental Science and Technology.2024; 21(5): 5247.     CrossRef
  • Control of cluster coalescence during formation of bimetallic nanoparticles and nanoalloys obtained via electric explosion of two wires
    K.V. Suliz, A.Yu. Kolosov, V.S. Myasnichenko, N.I. Nepsha, N.Yu. Sdobnyakov, A.V. Pervikov
    Advanced Powder Technology.2022; 33(3): 103518.     CrossRef
Article image
[Korean]
Austenite Stability of Sintered Fe-based Alloy
Seunggyu Choi, Namhyuk Seo, Junhyub Jun, Seung Bae Son, Seok-Jae Lee
J Korean Powder Metall Inst. 2020;27(5):414-419.   Published online October 1, 2020
DOI: https://doi.org/10.4150/KPMI.2020.27.5.414
  • 1,023 View
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AbstractAbstract PDF

In the present study, we investigated the austenite stability of a sintered Fe-based nanocrystalline alloy. The volume fraction of austenite was measured based on the X-ray diffraction data of sintered Fe-based nanocrystalline alloys, which were prepared by high-energy ball milling and spark plasma sintering. The sintered alloy samples showed a higher volume fraction of austenite at room temperature as compared to the equilibrium volume fraction of austenite obtained using thermodynamic calculations, which resulted from the nanosized crystalline structure of the sintered alloy. It was proved that the austenite stability of the sintered Fe-based alloy increased with a rise in the amount of austenite stabilizing elements such as Mn, Ni, and C; however, it increased more effectively with a decrease in the actual grain size. Furthermore, we proposed a new equation to predict the martensite starting temperature for sintered Fe-based alloys.

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[Korean]
Synthesis and Nucleation Behavior of MoO3 Nano Particles with Concentration of Precursors
Seyoung Lee, Namhun Kwon, Jaeseok Roh, Kun-Jae Lee
J Korean Powder Metall Inst. 2020;27(5):394-400.   Published online October 1, 2020
DOI: https://doi.org/10.4150/KPMI.2020.27.5.394
  • 1,215 View
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  • 1 Citations
AbstractAbstract PDF

Molybdenum trioxide (MoO3) is used in various applications including sensors, photocatalysts, and batteries owing to its excellent ionic conductivity and thermal properties. It can also be used as a precursor in the hydrogen reduction process to obtain molybdenum metals. Control of the parameters governing the MoO3 synthesis process is extremely important because the size and shape of MoO3 in the reduction process affect the shape, size, and crystallization of Mo metal. In this study, we fabricated MoO3 nanoparticles using a solution combustion synthesis (SCS) method that utilizes an organic additive, thereby controlling their morphology. The nucleation behavior and particle morphology were confirmed using ultraviolet-visible spectroscopy (UV-vis) and field emission scanning electron microscopy (FE-SEM). The concentration of the precursor (ammonium heptamolybdate tetrahydrate) was adjusted to be 0.1, 0.2, and 0.4 M. Depending on this concentration, different nucleation rates were obtained, thereby resulting in different particle morphologies.

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  • Characterization of Compacted and Pressureless Sintered Parts for Molybdenum Oxide Powder according to Hydrogen Reduction Temperature
    Jong Hoon Lee, Kun-Jae Lee
    Journal of Powder Materials.2024; 31(4): 336.     CrossRef
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[Korean]
Study on the Preparation of TiO2 3D Nanostructure for Photocatalyst by Wet Chemical Process
Duk-Hee Lee, Jae-Ryang Park, Chan-Gi Lee, Kyoung-Tae Park, Kyung-Soo Park
J Korean Powder Metall Inst. 2020;27(5):381-387.   Published online October 1, 2020
DOI: https://doi.org/10.4150/KPMI.2020.27.5.381
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AbstractAbstract PDF

In this work, TiO2 3D nanostructures (TF30) were prepared via a facile wet chemical process using ammonium hexafluorotitanate. The synthesized 3D TiO2 nanostructures exhibited well-defined crystalline and hierarchical structures assembled from TiO2 nanorods with different thicknesses and diameters, which comprised numerous small beads. Moreover, the maximum specific surface area of TiO2 3D nanostructures was observed to be 191 m2g-1, with concentration of F ions on the surface being 2 at%. The TiO2 3D nanostructures were tested as photocatalysts under UV irradiation using Rhodamine B solution in order to determine their photocatalytic performance. The TiO2 3D nanostructures showed a higher photocatalytic activity than that of the other TiO2 samples, which was likely associated with the combined effects of a high crystallinity, unique features of the hierarchical structure, a high specific surface area, and the advantage of adsorbing F ions.

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[English]
Correlation of Sintering Parameters with Density and Hardness of Nano-sized Titanium Nitride reinforced Titanium Alloys using Neural Networks
A. K. Maurya, P. L Narayana, Hong In Kim, N. S. Reddy
J Korean Powder Metall Inst. 2020;27(5):365-372.   Published online October 1, 2020
DOI: https://doi.org/10.4150/KPMI.2020.27.5.365
  • 1,144 View
  • 6 Download
  • 1 Citations
AbstractAbstract PDF

Predicting the quality of materials after they are subjected to plasma sintering is a challenging task because of the non-linear relationships between the process variables and mechanical properties. Furthermore, the variables governing the sintering process affect the microstructure and the mechanical properties of the final product. Therefore, an artificial neural network modeling was carried out to correlate the parameters of the spark plasma sintering process with the densification and hardness values of Ti-6Al-4V alloys dispersed with nano-sized TiN particles. The relative density (%), effective density (g/cm3), and hardness (HV) were estimated as functions of sintering temperature (°C), time (min), and composition (change in % TiN). A total of 20 datasets were collected from the open literature to develop the model. The high-level accuracy in model predictions (>80%) discloses the complex relationships among the sintering process variables, product quality, and mechanical performance. Further, the effect of sintering temperature, time, and TiN percentage on the density and hardness values were quantitatively estimated with the help of the developed model.

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  • Application of Machine Learning Algorithms and SHAP for Prediction and Feature Analysis of Tempered Martensite Hardness in Low-Alloy Steels
    Junhyub Jeon, Namhyuk Seo, Seung Bae Son, Seok-Jae Lee, Minsu Jung
    Metals.2021; 11(8): 1159.     CrossRef
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[Korean]
Partially Dry-Transferred Graphene Electrode with Zinc Oxide Nanopowder and Its Application on Organic Solar Cells
Yeongsu Jo, Chae Young Woo, Soon Kyu Hong, Hyung Woo Lee
J Korean Powder Metall Inst. 2020;27(4):305-310.   Published online August 1, 2020
DOI: https://doi.org/10.4150/KPMI.2020.27.4.305
  • 401 View
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AbstractAbstract PDF

In this study, partially dry transfer is investigated to solve the problem of fully dry transfer. Partially dry transfer is a method in which multiple layers of graphene are dry-transferred over a wet-transferred graphene layer. At a wavelength of 550 nm, the transmittance of the partially dry-transferred graphene is seen to be about 3% higher for each layer than that of the fully dry-transferred graphene. Furthermore, the sheet resistance of the partially drytransferred graphene is relatively lower than that of the fully dry-transferred graphene, with the minimum sheet resistance being 179 Ω/sq. In addition, the fully dry-transferred graphene is easily damaged during the solution process, so that the performance of the organic photovoltaics (OPV) does not occur. In contrast, the best efficiency achievable for OPV using the partially dry-transferred graphene is 2.37% for 4 layers.

Review Paper
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[Korean]
Recent Development in Performance Enhancement of PVDF-Nanopowder Composite-based Energy Harvesting Devices
Geon-Ju Choi, Il-Kyu Park
J Korean Powder Metall Inst. 2020;27(3):247-255.   Published online June 1, 2020
DOI: https://doi.org/10.4150/KPMI.2020.27.3.247
  • 882 View
  • 11 Download
AbstractAbstract PDF

Recently, interest in technology for eco-friendly energy harvesting has been increasing. Polyvinylidene fluoride (PVDF) is one of the most fascinating materials that has been used in energy harvesting technology as well as micro-filters by utilizing an electrostatic effect. To enhance the performance of the electrostatic effect-based nanogenerator, most studies have focused on enlarging the contact surface area of the pair of materials with different triboelectric series. For this reason, one-dimensional nanofibers have been widely used recently. In order to realize practical energy-harvesting applications, PVDF nanofibers are modified by enlarging their contact surface area, modulating the microstructure of the surface, and maximizing the fraction of the β-phase by incorporating additives or forming composites with inorganic nanoparticles. Among them, nanocomposite structures incorporating various nanoparticles have been widely investigated to increase the β-phase through strong hydrogen bonding or ion-dipole interactions with -CF2/CH2- of PVDF as well as to enhance the mechanical strength. In this study, we report the recent advances in the nanocomposite structure of PVDF nanofibers and inorganic nanopowders.

Article
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[Korean]
Influence of Reducing Agents and Additives on the Synthesis of ZnSe Nanoparticles
Geum Ji Back, Da Gyeong Lee, Min Seo Lee, Ha Yeon Song, Hyun Seon Hong
J Korean Powder Metall Inst. 2020;27(3):233-240.   Published online June 1, 2020
DOI: https://doi.org/10.4150/KPMI.2020.27.3.233
  • 461 View
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AbstractAbstract PDF

Nano-sized ZnSe particles are successfully synthesized in an aqueous solution at room temperature using sodium borohydride (NaBH4) and thioglycolic acid (TGA) as the reducing agent and stabilizer, respectively. The effects of the mass ratio of the reducing agent to Se, stabilizer concentration, and stirring time on the synthesis of the ZnSe nanoparticles are evaluated. The light absorption/emission properties of the synthesized nanoparticles are characterized using ultraviolet-visible (UV-vis) spectroscopy, photoluminescence (PL) spectroscopy, and particle size analyzer (PSA) techniques. At least one mass ratio (NaBH4/Se) of the reducing agent should be added to produce ZnSe nanoparticles finer than 10 nm and to absorb UV–vis light shorter than the ZnSe bulk absorption wavelength of 460 nm. As the ratio of the reducing agent increases, the absorption wavelengths in the UV-vis curves are blue-shifted. Stirring in the atmosphere acts as a deterrent to the reduction reaction and formation of nanoparticles, but if not stirred in the atmosphere, the result is on par with synthesis in a nitrogen atmosphere. The stabilizer, TGA, has an impact on the Zn precursor synthesis. The fabricated nanoparticles exhibit excellent photo-absorption/discharge characteristics, suggesting that ZnSe nanoparticles can be alloyed without the need for organic solutions or high-temperature environments.

Review Paper
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[Korean]
Fluorescent Nanoparticles: Synthesis and Applications
Y. K. Kim, B. K. Song, J. G. Lee, Y. K. Baek
J Korean Powder Metall Inst. 2020;27(2):154-163.   Published online April 1, 2020
DOI: https://doi.org/10.4150/KPMI.2020.27.2.154
  • 2,523 View
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  • 1 Citations
AbstractAbstract PDF

Fluorescent nanoparticles are characterized by their unique properties such as luminescence, optical transparency, and sensitivity to various chemical environments. For example, semiconductor nanocrystals (quantum dots), which are nanophosphors doped with transition metal or rare earth ions, can be classified as fluorescent nanoparticles. Tuning their optical and physico-chemical properties can be carried out by considering and taking advantage of nanoscale effects. For instance, quantum confinement causes a much higher fluorescence with nanoparticles than with their bulk counterparts. Recently, various types of fluorescent nanoparticles have been synthesized to extend their applications to other fields. In this study, State-of-the-art fluorescent nanoparticles are reviewed with emphasis on their analytical and anti-counterfeiting applications and synthesis processes. Moreover, the fundamental principles behind the exceptional properties of fluorescent nanoparticles are discussed.

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  • Preparation and Analysis of High Functional Silicone Hydrogel Lens Containing Metal Oxide Nanoparticles by Photopolymerizaion
    Ji-Won Heo, A-Young Sung
    Korean Journal of Materials Research.2022; 32(4): 193.     CrossRef
Articles
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[English]
Spark Plasma Sintering of the Ni-graphite Composite Powder Prepared by Electrical Explosion of Wire in Liquid and Its Properties
Minh Thuyet-Nguyena, Jin-Chun Kim
J Korean Powder Metall Inst. 2020;27(1):14-24.   Published online February 1, 2020
DOI: https://doi.org/10.4150/KPMI.2020.27.1.14
  • 720 View
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  • 2 Citations
AbstractAbstract PDF

In this work, the electrical explosion of wire in liquid and subsequent spark plasma sintering (SPS) was introduced for the fabrication of Ni-graphite nanocomposites. The fabricated composite exhibited good enhancements in mechanical properties, such as yield strength and hardness, but reduced the ductility in comparison with that of nickel. The as-synthesized Ni-graphite (5 vol.% graphite) nanocomposite exhibited a compressive yield strength of 275 MPa (about 1.6 times of SPS-processed monolithic nickel ~170 MPa) and elongation to failure ~22%. The hardness of Nigraphite composite had a value of 135.46 HV, which is about 1.3 times higher than that of pure SPS-processed Ni (105.675 HV). In terms of processing, this work demonstrated that this processing route is a novel, simple, and low-cost method for the synthesis of nickel-graphite composites.

Citations

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  • Top-down strategies for achieving high-quality graphene: Recent advancements
    Arpana Agrawal
    Journal of Industrial and Engineering Chemistry.2025; 142: 103.     CrossRef
  • Electrodeposition of nickel-titanium dioxide coatings and powders from aqueous sulfate solutions
    Tazhibayeva Aigerim Shotaevna, Bayeshova Azhar Kospanovna, Bayeshov Abduali, Osińska Małgorzata
    Polyhedron.2025; 277: 117571.     CrossRef
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[Korean]
Synthesis of the Multifunctional Core/Intermediate/Shell Nanoparticles: Tunable Magnetic and Photoluminescence Properties
Mun-Kyoung Kim, Seyun Kim, Kyoung-Seok Moon, Weon Ho Shin, Hyung Mo Jeong
J Korean Powder Metall Inst. 2019;26(6):463-470.   Published online December 1, 2019
DOI: https://doi.org/10.4150/KPMI.2019.26.6.463
  • 536 View
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AbstractAbstract PDF

Fe3O4/SiO2/YVO4:Eu3+ multifunctional nanoparticles are successfully synthesized by facile stepwise sol-gel processes. The multifunctional nanoparticles show a spherical shape with narrow size distribution (approximately 40 nm) and the phosphor shells are well crystallized. The Eu3+ shows strong photoluminescence (red emission at 619 nm, absorbance at 290 nm) due to an effective energy transfer from the vanadate group to Eu. Core-shell structured multifunctional nanoparticles have superparamagnetic properties at 300 K. Furthermore, the core-shell nanoparticles have a quick response time for the external magnetic field. These results suggest that the photoluminescence and magnetic properties could be easily tuned by either varying the number of coating processes or changing the phosphor elements. The nanoparticles may have potential applications for appropriate fields such as laser systems, optical amplifiers, security systems, and drug delivery materials.

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[Korean]
Austenite Stability of Nanocrystalline FeMnNiC Alloy
Seung-Jin Oh, Junhyub Jeon, In-Jin Shon, Seok-Jae Lee
J Korean Powder Metall Inst. 2019;26(5):389-394.   Published online October 1, 2019
DOI: https://doi.org/10.4150/KPMI.2019.26.5.389
  • 696 View
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  • 2 Citations
AbstractAbstract PDF

In the present study, we have investigated the effect of sintering process conditions on the stability of the austenite phase in the nanocrystalline Fe-5wt.%Mn-0.2wt.%C alloy. The stability and volume fraction of the austenite phase are the key factors that determine the mechanical properties of FeMnC alloys, because strain-induced austenitemartensite transformation occurs under the application of an external stress at room temperature. Nanocrystalline Fe-5wt.%Mn-0.2wt.%C samples are fabricated using the spark plasma sintering method. The stability of the austenite phase in the sintered samples is evaluated by X-ray diffraction analysis and hardness test. The volume fraction of austenite at room temperature increases as the sample is held for 10 min at the sintering temperature, because of carbon diffusion in austenite. Moreover, water quenching effectively prevents the formation of cementite during cooling, resulting in a higher volume fraction of austenite. Furthermore, it is found that the hardness is influenced by both the austenite carbon content and volume fraction.

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  • Influence of Cobalt Content on Austenite Stability and Strain-Induced Martensite Transformation of Nanocrystalline Fe-7Mn Alloy Fabricated by Spark Plasma Sintering
    Sungjin Kim, Seung Bae Son, Seok-Jae Lee
    MATERIALS TRANSACTIONS.2025; 66(7): 811.     CrossRef
  • Austenite Stability of Sintered Fe-based Alloy
    Seunggyu Choi, Namhyuk Seo, Junhyub Jun, Seung Bae Son, Seok-Jae Lee
    Journal of Korean Powder Metallurgy Institute.2020; 27(5): 414.     CrossRef
Review Paper
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[English]
Synthesis of Nanosized Nickel Particle from Spent Cathodic Material Containing Lithium
Jei-Pil Wang
J Korean Powder Metall Inst. 2019;26(4):340-344.   Published online August 1, 2019
DOI: https://doi.org/10.4150/KPMI.2019.26.4.340
  • 573 View
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AbstractAbstract PDF

Due to the rapid development of electricity, electronics, information communication, and biotechnology in recent years, studies are actively being conducted on nanopowders as it is required not only for high strengthening but also for high-function powder with electric, magnetic, and optical properties. Nonetheless, studies on nickel nanopowders are rare. In this study of the synthesis of nickel nanoparticles from LiNiO2 (LNO), which is a cathode active material, we have synthesized the nanosized nickel powder by the liquid reduction process of NiSO4 obtained through the leaching and purification of LNO. Moreover, we have studied the reduction reaction rate according to the temperature change of liquid phase reduction and the change of particle size as a function of NaOH addition amount using hydrazine monohydrate (N2H4·H2O) and NaOH.

Articles
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[Korean]
Study on the Optimization of Reduction Conditions for Samarium-Cobalt Nanofiber Preparation
Jimin Lee, Jongryoul Kim, Yong-Ho Choa
J Korean Powder Metall Inst. 2019;26(4):334-339.   Published online August 1, 2019
DOI: https://doi.org/10.4150/KPMI.2019.26.4.334
  • 418 View
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AbstractAbstract PDF

To meet the current demand in the fields of permanent magnets for achieving a high energy density, it is imperative to prepare nano-to-microscale rare-earth-based magnets with well-defined microstructures, controlled homogeneity, and magnetic characteristics via a bottom-up approach. Here, on the basis of a microstructural study and qualitative magnetic measurements, optimized reduction conditions for the preparation of nanostructured Sm-Co magnets are proposed, and the elucidation of the reduction-diffusion behavior in the binary phase system is clearly manifested. In addition, we have investigated the microstructural, crystallographic, and magnetic properties of the Sm-Co magnets prepared under different reduction conditions, that is, H2 gas, calcium, and calcium hydride. This work provides a potential approach to prepare high-quality Sm-Co-based nanofibers, and moreover, it can be extended to the experimental design of other magnetic alloys.

Article image
[Korean]
Study on the Optimization of Reduction Conditions for Samarium-Cobalt Nanofiber Preparation
Jimin Lee, Jongryoul Kim, Yong-Ho Choa
J Korean Powder Metall Inst. 2019;26(4):334-339.   Published online August 1, 2019
DOI: https://doi.org/10.4150/KPMI.2019.26.4.334
  • 401 View
  • 2 Download
AbstractAbstract PDF

To meet the current demand in the fields of permanent magnets for achieving a high energy density, it is imperative to prepare nano-to-microscale rare-earth-based magnets with well-defined microstructures, controlled homogeneity, and magnetic characteristics via a bottom-up approach. Here, on the basis of a microstructural study and qualitative magnetic measurements, optimized reduction conditions for the preparation of nanostructured Sm-Co magnets are proposed, and the elucidation of the reduction-diffusion behavior in the binary phase system is clearly manifested. In addition, we have investigated the microstructural, crystallographic, and magnetic properties of the Sm-Co magnets prepared under different reduction conditions, that is, H2 gas, calcium, and calcium hydride. This work provides a potential approach to prepare high-quality Sm-Co-based nanofibers, and moreover, it can be extended to the experimental design of other magnetic alloys.

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[English]
Modeling the Density and Hardness of AA2024-SiC Nanocomposites
A-Hyun Jeon, Hong In Kim, Hyokyung Sung, N. S. Reddy
J Korean Powder Metall Inst. 2019;26(4):275-281.   Published online August 1, 2019
DOI: https://doi.org/10.4150/KPMI.2019.26.4.275
  • 801 View
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AbstractAbstract PDF

An artificial neural network (ANN) model is developed for the analysis and simulation of correlation between flake powder metallurgy parameters and properties of AA2024-SiC nanocomposites. The input parameters of the model are AA 2024 matrix size, ball milling time, and weight percentage of SiC nanoparticles and the output parameters are density and hardness. The model can predict the density and hardness of the unseen test data with a correlation of 0.986 beyond the experimental data. A user interface is designed to predict properties at new instances. We have used the model to simulate the individual as well as the combined influence of parameters on the properties. Moreover, we have analyzed the calculated results from the powder metallurgical point of view. The developed model can be used as a guide for further composite development.

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[Korean]
Effect of Pyrolysis temperature on TiO2 Nanoparticles Synthesized by a Salt-assisted Ultrasonic Spray Pyrolysis Process
Jae-Hyun Yoo, Myeong-Jun Ji, Woo-Young Park, Young-In Lee
J Korean Powder Metall Inst. 2019;26(3):237-242.   Published online June 1, 2019
DOI: https://doi.org/10.4150/KPMI.2019.26.3.237
  • 639 View
  • 4 Download
  • 1 Citations
AbstractAbstract PDF

In this study, ultrasonic spray pyrolysis combined with salt-assisted decomposition, a process that adds sodium nitrate (NaNO3) into a titanium precursor solution, is used to synthesize nanosized titanium dioxide (TiO2) particles. The added NaNO3 prevents the agglomeration of the primary nanoparticles in the pyrolysis process. The nanoparticles are obtained after a washing process, removing NaNO3 and NaF from the secondary particles, which consist of the salts and TiO2 nanoparticles. The effects of pyrolysis temperature on the size, crystallographic characteristics, and bandgap energy of the synthesized nanoparticles are systematically investigated. The synthesized TiO2 nanoparticles have a size of approximately 2–10 nm a bandgap energy of 3.1–3.25 eV, depending on the synthetic temperature. These differences in properties affect the photocatalytic activities of the synthesized TiO2 nanoparticles.

Citations

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  • Microstructure and Sintering Behavior of Fine Tungsten Powders Synthesized by Ultrasonic Spray Pyrolysis
    Hyeonhui Jo, Jeong Hyun Kim, Young-In Lee, Young-Keun Jeong, Sung-Tag Oh
    Korean Journal of Metals and Materials.2021; 59(5): 289.     CrossRef

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