Lithium (Li) is a key resource driving the rapid growth of the electric vehicle industry globally, with demand and prices continually on the rise. To address the limited reserves of major lithium sources such as rock and brine, research is underway on seawater Li extraction using electrodialysis and Li-ion selective membranes. Lithium lanthanum titanate (LLTO), an oxide solid electrolyte for all-solid-state batteries, is a promising Li-ion selective membrane. An important factor in enhancing its performance is employing the powder synthesis process. In this study, the LLTO powder is prepared using two synthesis methods: sol-gel reaction (SGR) and solid-state reaction (SSR). Additionally, the powder size and uniformity are compared, which are indices related to membrane performance. X-ray diffraction and scanning electron microscopy are employed for determining characterization, with crystallite size analysis through the full width at half maximum parameter for the powders prepared using the two synthetic methods. The findings reveal that the powder SGR-synthesized powder exhibits smaller and more uniform characteristics (0.68 times smaller crystal size) than its SSR counterpart. This discovery lays the groundwork for optimizing the powder manufacturing process of LLTO membranes, making them more suitable for various applications, including manufacturing high-performance membranes or mass production of membranes.

The demand for energy is steadily rising because of rapid population growth and improvements in living standards. Consequently, extensive research is being conducted worldwide to enhance the energy supply. Transpiration power generation technology utilizes the vast availability of water, which encompasses more than 70% of the Earth's surface, offering the unique advantage of minimal temporal and spatial constraints over other forms of power generation. Various principles are involved in water-based energy harvesting. In this study, we focused on explaining the generation of energy through the streaming potential within the generator component. The generator was fabricated using sugar cubes, PDMS, carbon black, CTAB, and DI water. In addition, a straightforward and rapid manufacturing method for the generator was proposed. The PDMS generator developed in this study exhibits high performance with a voltage of 29.6 mV and a current of 8.29 μA and can generate power for over 40h. This study contributes to the future development of generators that can achieve high performance and long-term power generation.

Rare earth elements, which are important components of motors, are in high demand and thus constantly get more expensive. This tendency is driven by the growth of the electric vehicle market, as well as environmental issues associated with rare-earth metal manufacturing. TC 298 of the ISO manages standardization in the areas of rare-earth recycling, measurement, and sustainability. Korea, a resource-poor country, is working on international standardization projects that focus on recycling and encouraging the domestic adoption of international standards. ITU-T has previously issued recommendations regarding the recycling of rare-earth metals from e-waste. ISO TC 298 expands on the previous recommendations and standards for promoting the recycling industry. Recycling-related rare earth standards and drafts covered by ISO TC 298, as well as Korea’s strategies, are reviewed and discussed in this article.

Magnetic 0-D Nd₂Fe₁₄B powders are successfully fabricated using 1-D Nd₂Fe₁₄B nanowire formed by an efficient and facile electrospinning process approach. The synthesized Nd-Fe-B fibers and powders are investigated for their microstructural, crystallographic, and magnetic properties according to a series of subsequent heat treatments. Each heat-treatment process leads to the removal of organic impurities and the formation of the respective oxides/composites of Nd, Fe, and B, resulting in the formation of Nd₂Fe₁₄B powders. Nd-Fe-B fibers exhibit the following magnetic properties: The coercivity (H_ci) of 3260 Oe, a maximum magnetization at 3T of 109.44 emu/g, and a magnetization remanence (M_r) of 44.11 emu/g. This process easily mass produces hard magnetic Nd₂Fe₁₄B powders using a 1-D synthesis process and can be extended to the experimental design of other magnetic materials.

Citations

Citations to this article as recorded by  

• Nd2Fe14B/FeCo Core–Shell Nanoparticle Synthesis Using Galvanic Substitution Based Electroless Plating
  Muhammad Aneeq Haq, Han-Saem Lee, Mi Hye Lee, Da-Woon Jeong, Eom Nu Si A, Bin Lee, Yoseb Song, Bum Sung Kim
  Coatings.2022; 12(3): 389.     CrossRef

With increasing demand for resources worldwide, Korea has been negotiating with resource-holding countries to achieve conservation of energy resources. Among them, Russia is the third largest resource-producing and exporting nation in the world and has several resource materials such as nickel, platinum group metals, gold, and other reserves. As a result, there is growing interest in cooperation between Korea and Russia. The aim of this article is to summarize the current status of market flow of Russian energy resources as well as Russia’s economic cooperation with Korea. Notably, South Korea needs to focus on investing in overseas mines for a stable supply of rare metals. Nevertheless, securing rare metals is a major task by understanding the flow and policy direction of Russian material mines.

Since the ISO decided to deal with rare-earth elements at the 298^th Technical Committee (TC) in 2015, Korea has participated in four plenary meetings and proposed four standards as of June 2019. The status of ISO TC 298, the standards covered by the TC, and the standardization strategies of Korea are summarized. Korean delegations are actively engaged in WG2, which deals with recycling, proposing four standards for fostering the rare-earth recycling industry. However, the participation of domestic experts is still low compared with the increase in the number of working groups and the number of standards in TC 298. The aim of this article is to summarize the current status of ISO international standards related to rare-earth elements, to encourage relevant experts to participate in standardization, and to develop international standards that accurately reflect the realities of the industry.

In this study, we investigate the optical properties of InP/ZnS core/shell quantum dots (QDs) by controlling the synthesis temperature of InP. The size of InP determined by the empirical formula tends to increase with temperature: the size of InP synthesized at 140oC and 220oC is 2.46 nm and 4.52 nm, respectively. However, the photoluminescence (PL) spectrum of InP is not observed because of the formation of defects on the InP surface. The growth of InP is observed during the deposition of the shell (ZnS) on the synthesized InP, which is ended up with green-red PL spectrum. We can adjust the PL spectrum and absorption spectrum of InP/ZnS by simply adjusting the core temperature. Thus, we conclude that there exists an optimum shell thickness for the QDs according to the size.

Citations

Citations to this article as recorded by  

• Study on Surface-defect Passivation of InP System Quantum Dots by Photochemical Method
  Doyeon Kim, Hyun-Su Park, Hye Mi Cho, Bum-Sung Kim, Woo-Byoung Kim
  Journal of Korean Powder Metallurgy Institute.2017; 24(6): 489.     CrossRef

This study investigates the main growth mechanism of InP during InP/ZnS reaction of quantum dots (QDs). The size of the InP core, considering a synthesis time of 1-30 min, increased from the initial 2.56 nm to 3.97 nm. As a result of applying the proposed particle growth model, the migration mechanism, with time index 7, was found to be the main reaction. In addition, after the removal of unreacted In and P precursors from bath, further InP growth (of up to 4.19 nm (5%)), was observed when ZnS was added. The full width at half maximum (FWHM) of the synthesized InP/ZnS quantum dots was found to be relatively uniform, measuring about 59 nm. However, kinetic growth mechanism provides limited information for InP / ZnS core shell QDs, because the surface state of InP changes with reaction time. Further study is necessary, in order to clearly determine the kinetic growth mechanism of InP / ZnS core shell QDs.

Quantum dots (QDs) are capable of controlling the typical emission and absorption wavelengths because of the bandgap widening effect of nanometer-sized particles. These phosphor particles have been used in optical devices, photovoltaic devices, advanced display devices, and several biomedical complexes. In this study, we synthesize ZnSe QDs with controlled surface defects by a heating-up method. The optical properties of the synthesized particles are analyzed using UV-visible and photoluminescence (PL) measurements. Calculations indicate nearly monodisperse particles with a size of about 5.1 nm at 260°C (full width at half maximum = 27.7 nm). Furthermore, the study results confirm that successful doping is achieved by adding Eu³⁺ preparing the growth phase of the ZnSe:Eu QDs when heating-up method. Further, we investigate the correlation between the surface defects and the luminescent properties of the QDs.

Citations

Citations to this article as recorded by  

• An investigation into the effective surface passivation of quantum dots by a photo-assisted chemical method
  So-Yeong Joo, Hyun-Su Park, Do-yeon Kim, Bum-Sung Kim, Chan Gi Lee, Woo-Byoung Kim
  AIP Advances.2018;[Epub]     CrossRef
• Multimodal luminescence properties of surface-treated ZnSe quantum dots by Eu
  Ji Young Park, Da-Woon Jeong, Kyoung-Mook Lim, Yong-Ho Choa, Woo-Byoung Kim, Bum Sung Kim
  Applied Surface Science.2017; 415: 8.     CrossRef

Owing to increasing demand of rare metals present in ICT products, it is necessary to promote the rare metal recycling industry from an environmental viewpoint and to prevent climate change. Despite the fact that information for toxic substances is partly indicated, a legal basis and an international standard indicating usage of rare metals is insufficient. In order to address this issue, a newly created study group of environment and climate change at the ITU (International Telecommunication Union) is doing research to develop methodologies for recycling rare metals from ICT products in an eco-friendly way. Under this group, the Republic of Korea has established two international standards related to rare metals present in ICT products. The first is ‘Release of rare metal information for ICT products (ITU-T L.1100)’ and the other is ‘Quantitative and qualitative analysis methods for rare metals (ITU-T L.1101)’. A new proposal for recommending the provision of rare metal information through a label by manufacturers and consumer/recycling businesses has been approved recently and is supposed to be published later in 2016. Moreover, these recommendations are also being extended to IEC, ISO and other standardization organizations and a strategy to reinforce the ability for domestic standardization is being established in accordance with industrial requirements. This will promote efficient recycling of rare metals from ICT products and will help improve the domestic supply of rare metals.

Citations

Citations to this article as recorded by  

• Russian Mineral Market Flow and Economic Direction for Securing Stable Resources
  Nu Si A Eom, Su Noh, Muhammad Aneeq Haq, Bin Lee, Kyoung Mook Lim, Bum Sung Kim
  Journal of Korean Powder Metallurgy Institute.2019; 26(4): 345.     CrossRef
• Trends and Implications of International Standardization for Rare Earths
  Sardar Farhat Abbas, Sang-Hyun lee, Bin Lee, Bum-Sung Kim, Taek-Soo Kim
  Journal of Korean Powder Metallurgy Institute.2018; 25(2): 165.     CrossRef

High-quality colloidal CdSe/ZnS (core/shell) is synthesized using a continuous microreactor. The particle size of the synthesized quantum dots (QDs) is a function of the precursor flow rate; as the precursor flow rate increases, the size of the QDs decreases and the band gap energy increases. The photoluminescence properties are found to depend strongly on the flow rate of the CdSe precursor owing to the change in the core size. In addition, a gradual shift in the maximum luminescent wave (λ_max) to shorter wavelengths (blue shift) is found owing to the decrease in the QD size in accordance with the quantum confinement effect. The ZnS shell decreases the surface defect concentration of CdSe. It also lowers the thermal energy dissipation by increasing the concentration of recombination. Thus, a relatively high emission and quantum yield occur because of an increase in the optical energy emitted at equal concentration. In addition, the maximum quantum yield is derived for process conditions of 0.35 ml/min and is related to the optimum thickness of the shell material.

Citations

Citations to this article as recorded by  

• Quantum materials made in microfluidics - critical review and perspective
  M. Wojnicki, V. Hessel
  Chemical Engineering Journal.2022; 438: 135616.     CrossRef
• Poly(methylmethacrylate) coating on quantum dot surfaces via photo-chemical reaction for defect passivation
  Doyeon Kim, So-Yeong Joo, Chan Gi Lee, Bum-Sung Kim, Woo-Byoung Kim
  Journal of Photochemistry and Photobiology A: Chemistry.2019; 376: 206.     CrossRef
• Multimodal luminescence properties of surface-treated ZnSe quantum dots by Eu
  Ji Young Park, Da-Woon Jeong, Kyoung-Mook Lim, Yong-Ho Choa, Woo-Byoung Kim, Bum Sung Kim
  Applied Surface Science.2017; 415: 8.     CrossRef

The monolayer engineering diamond particles are aligned on the oxygen free Cu plates with electroless Ni plating layer. The mean diamond particle sizes of 15, 23 and 50 μm are used as thermal conductivity pathway for fabricating metal/carbon multi-layer composite material systems. Interconnected void structure of irregular shaped diamond particles allow dense electroless Ni plating layer on Cu plate and fixing them with 37-43% Ni thickness of their mean diameter. The thermal conductivity decrease with increasing measurement temperature up to 150°C in all diamond size conditions. When the diamond particle size is increased from 15 μm to 50 μm (Max. 304 W/mK at room temperature) tended to increase thermal conductivity, because the volume fraction of diamond is increased inside plating layer.

Citations

Citations to this article as recorded by  

• Machinability Evaluation of Hybrid Ti2Ceramic Composites with Conductivity in Micro Electrical Discharge Drilling Operation
  Jae-Young Heo, Young-Keun Jeong, Myung-Chang Kang, Ahmed Busnaina
  Journal of Korean Powder Metallurgy Institute.2013; 20(4): 285.     CrossRef

Citations

Citations to this article as recorded by  

• Synthesis and analysis CdSe/ZnS quantum dot with a Core/shell Continuous Synthesis System Using a Microfluidic Reactor
  Myung Hwan Hong, So Young Joo, Lee-Seung Kang, Chan Gi Lee
  Journal of Korean Powder Metallurgy Institute.2018; 25(2): 132.     CrossRef
• Multimodal luminescence properties of surface-treated ZnSe quantum dots by Eu
  Ji Young Park, Da-Woon Jeong, Kyoung-Mook Lim, Yong-Ho Choa, Woo-Byoung Kim, Bum Sung Kim
  Applied Surface Science.2017; 415: 8.     CrossRef
• Optical Characteristics of CdSe/ZnS Quantum Dot with Precursor Flow Rate Synthesized by using Microreactor
  Ji Young Park, Da-Woon Jeong, Won Ju, Han Wook Seo, Yong-Ho Choa, Bum Sung Kim
  journal of Korean Powder Metallurgy Institute.2016; 23(2): 91.     CrossRef