Article
Materials Science, Multidisciplinary
Hung Ba Tran, Yu-ichiro Matsushita
Summary: The mechanism of spin reorientation in Nd2Fe14B, the host crystal of neodymium permanent magnets, was investigated using first-principles calculations and Monte Carlo simulations. It was found that the spin reorientation in Nd2Fe14B is caused by Dzyaloshinskii-Moriya interactions, which have been often ignored in rare-earth bulk systems. This study also discovered that the spin reorientation in Nd2Fe14B results in the rotating magnetocaloric effect, which has potential practical applications. Moreover, the Dzyaloshinskii-Moriya interactions non-negligibly affect the physical properties of magnetic materials.
APPLIED MATERIALS TODAY
(2023)
Article
Chemistry, Multidisciplinary
Namkyu Kim, Hee-Sung Han, Chul-Jin Choi, Ki-Suk Lee, Jihoon Park
Summary: This study investigated a model system using micromagnetic simulation and compared different methods of calculating energy products, revealing discrepancies in the calculation process and analyzing the magnet in the model system comprehensively.
APPLIED SCIENCES-BASEL
(2022)
Article
Chemistry, Physical
I. Dirba, P. Pattur, I. Soldatov, E. Adabifiroozjaei, L. Molina-Luna, O. Gutfleisch
Summary: This study investigates the effect of grain boundary phase magnetism on coercivity in the quaternary Nd-Fe-Ga-Cu system. It is found that adjusting the Ce and Fe content, as well as infiltrating different materials, can effectively enhance the coercivity and temperature stability of magnets. The findings provide a better understanding of the influence of grain boundary phase magnetism on coercivity.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Review
Materials Science, Multidisciplinary
Zhongwu Liu, Jiayi He, Raju V. Ramanujan
Summary: This review provides a critical description of the fundamentals and development of grain boundary diffusion process (GBDP) for enhancing coercivity of Nd-Fe-B magnets. It discusses the mechanisms, cost reduction, and challenges and opportunities for future development of GBDP and cost-effective permanent magnets.
MATERIALS & DESIGN
(2021)
Article
Chemistry, Physical
JungHo Park, HyunJun Kwon, Jong-Hwan Park, Jae Chul Ro, Su-Jeong Suh
Summary: Sm2Co17 magnetic materials were synthesized using electrodeposition and a reduction-diffusion (R-D) process, involving the use of a complex agent and a high-temperature transformation. X-ray diffraction analysis and magnetic property tests showed that the alloy transformed from an amorphous state to a crystalline form of Sm2Co17 after the R-D process.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Physics, Multidisciplinary
Chen-Hua Deng, Zhong-Hai Yu, Yu-Tao Wang, Kong Sen, Zhou Chao, Yang Sen
Summary: Nanocomposite magnet composed of magnetically hard and soft phases has potential for permanent magnet development. The addition of Ti in the crystallization process of the Nd2Fe14B/a-Fe magnet can change the crystallization kinetics and result in the formation of fine and uniform grains with an average size of about 20 nm. The optimized magnetic property is (BH)max = 12 MGmiddotOe when Ti addition is 1.0%.
ACTA PHYSICA SINICA
(2023)
Article
Materials Science, Multidisciplinary
C. S. Kim, L. Zha, M. N. Li, W. Y. Yang, J. Z. Han, S. Q. Liu, H. L. Du, C. S. Wang, J. B. Yang
Summary: This study investigates the impact of microstructure design on magnetic properties of exchange coupling nano-composite permanent magnets through micromagnetic modeling, finding that the grain size of the hard phase plays a critical role in enhancing the maximum energy product (BH)max. Additionally, simulations with a grain boundary phase show little difference compared to simulations without the grain boundary phase when the thickness of the grain boundary phase is very small, but coercivities and (BH)max decrease significantly with increasing soft phase when the thickness of the grain boundary phase is 5 nm.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2021)
Article
Chemistry, Inorganic & Nuclear
Rao Shuang, Lin Chen-Sheng, He Zhang-Zhen, Chai Guo-Liang
Summary: By systematically studying the isomorphic structure R2M14B compounds with first-principles density functional theory calculations, it was found that Pr is the most suitable rare-earth element alternative to Nd in Nd2Fe14B, and Co is a more suitable substitution for Fe compared to Mn and Ni due to their significant reduction of the magnetic moment.
CHINESE JOURNAL OF STRUCTURAL CHEMISTRY
(2021)
Article
Materials Science, Multidisciplinary
Yu-Yang Bian, Shu-Qiang Guo, Yu-Ling Xu, Kai Tang, Xiong-Gang Lu, Wei-Zhong Ding
Summary: A high-temperature pyrometallurgical process was developed to recover valuable rare earth elements from Nd-Fe-B permanent magnet scraps. By pulverizing and oxidizing the magnet scraps, the rare earth elements were extracted as oxides while separating Fe and B as metal phase. Temperature and reaction time were found to be crucial for improving the purity of rare earth oxides.
Article
Automation & Control Systems
Yan Wen, Guoli Li, Qunjing Wang, Xiwen Guo, Wenping Cao
Summary: This article applies Gaussian process to establish the relationship between rotor position and output torque for PMSMs, solving complex three-dimensional problems using a data-driven approach. It also develops multitask Gaussian process to calculate the total torque produced by multiple coils, exhibiting superior performance in accuracy.
IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS
(2021)
Article
Engineering, Multidisciplinary
Kyuil Cho, S. L. Bud'ko, P. C. Canfield
Summary: The temperature dependence of resistivity in single crystalline Nd2Fe14B was studied using a newly developed high temperature probe. It was found that there were anomalous discrete jumps in resistivity during cooling, accompanied by an increase in resistivity. This phenomenon may be attributed to a temperature dependent striction effect induced by the re-orientation of magnetic domains.
MEASUREMENT SCIENCE AND TECHNOLOGY
(2022)
Article
Metallurgy & Metallurgical Engineering
Liu Zhongwu, He Jiayi
Summary: Nd-Fe-B based permanent magnets are widely used in various industries, such as renewable energy, information and communication, and intelligent manufacturing. The introduction of heavy rare earth elements through the grain boundary diffusion process has led to significant improvements in coercivity and reduced consumption of heavy rare earth, enhancing the performance-cost ratio. However, technical and theoretical challenges still exist, including issues related to thick magnets, anisotropic behavior, diffusion sources, combination with existing processes, service performance, and theoretical advancements. Opportunities and challenges in the future development of the GBD process for Nd-Fe-B based magnets are also highlighted.
ACTA METALLURGICA SINICA
(2021)
Article
Engineering, Electrical & Electronic
Guanghui Du, Niumei Li, Qixun Zhou, Wentao Gao, Lu Wang, Tao Pu
Summary: This study comprehensively compared and analyzed the multi-physics performance of two rotor structures (SPM and IPM) in HSPMMs, providing guidance for designers in choosing a suitable rotor structure.
Article
Engineering, Electrical & Electronic
Wanwan Zhu, Yukai Yang, Hongzhou Song, Yinan Liu, Zaiping Zheng, Yiguang Chen
Summary: The unequal amplitude of cogging torque in different rotor positions due to the tolerance of stator and rotor stacks as well as nonuniform magnetization of permanent magnet makes it difficult to verify the theoretical analysis. Therefore, it is necessary to evaluate the cogging torque using its average value. A cogging torque measurement method is proposed for multi slot/pole permanent magnet motor, which accurately measures the amplitude and period of cogging torque without site restrictions through simple devices. The correctness of the method is verified by simulation and experiment and can be used as a supplement to cogging torque evaluation.
IET ELECTRIC POWER APPLICATIONS
(2023)
Article
Engineering, Electrical & Electronic
Vahid Zamani Faradonbeh, Akbar Rahideh
Summary: A fast hybrid analytical model is proposed to predict the on-load performance of double-layer IPMSMs considering iron bridges saturation and slotting effects. The model utilizes constant flux in the magnetic equivalent circuit method for iron bridges saturation and flux path function and VSCs for slotting effects in 1-D and 2-D analytical methods.
IET ELECTRIC POWER APPLICATIONS
(2022)
Article
Chemistry, Physical
Seungchan Cho, Yeong-Hwan Lee, Sungmin Ko, Hyeonjae Park, Donghyun Lee, Sangmin Shin, Ilguk Jo, Yangdo Kim, Sang-Bok Lee, Sang-Kwan Lee
JOURNAL OF ALLOYS AND COMPOUNDS
(2020)
Article
Energy & Fuels
Donghyeok Shin, SangWoon Lee, Dong Ryeol Kim, Joo Hyung Park, Yangdo Kim, Woo-Jin Choi, Chang Sik Son, Young Guk Son, Donghyun Hwang
Article
Energy & Fuels
Woo-Jin Choi, Wan Woo Park, Yangdo Kim, Chang Sik Son, Donghyun Hwang
Article
Chemistry, Physical
Yoo Sei Park, Jeong Hun Lee, Myeong Je Jang, Jaehoon Jeong, Sung Min Park, Woo-Sung Choi, Yangdo Kim, Juchan Yang, Sung Mook Choi
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2020)
Article
Materials Science, Multidisciplinary
Sung Min Park, Myeong Je Jang, Yoo Sei Park, Jooyoung Lee, Jae-yeop Jeong, Jaehoon Jung, Min-Kwan Choi, Yu-Seong Noh, Min-Ho Seo, Hyung Ju Kim, Juchan Yang, Yang Do Kim, Sung Mook Choi
KOREAN JOURNAL OF METALS AND MATERIALS
(2020)
Article
Materials Science, Multidisciplinary
Jae-Gyeong Yoo, Hee-Ryoung Cha, Dong-Hwan Kim, Yang-Do Kim, Jung-Goo Lee
JOURNAL OF MAGNETICS
(2020)
Article
Materials Science, Multidisciplinary
Yeong-Hwan Lee, Namkyu Kim, Sang-Bok Lee, Yangdo Kim, Seungchan Cho, Sang-Kwan Lee, Ilguk Jo
MATERIALS CHARACTERIZATION
(2020)
Article
Chemistry, Physical
Seongmin Ko, Hyeonjae Park, Yeong-Hwan Lee, Sangmin Shin, Ilguk Jo, Junghwan Kim, Sang-Bok Lee, Yangdo Kim, Sang-Kwan Lee, Seungchan Cho
Article
Chemistry, Physical
Jae Yong Jung, Juna Kim, Yang Do Kim, Young-Kuk Kim, Hee-Ryoung Cha, Jung-Goo Lee, Chang Sik Son, Donghyun Hwang
Summary: Hexagonal boron nitride nanophosphor particles were synthesized by pyrolysis with the addition of rare earth cerium ions for deep blue emission. Changes in crystallinity and luminescence were observed with increasing reheating temperature. The resulting cerium ion-doped hexagonal boron nitride nanoparticles were used in anti-counterfeiting applications by preparing an ink visible only under UV light.
Article
Materials Science, Multidisciplinary
Ilyeong Kwon, Takehiko Nagai, Shogo Ishizuka, Hitoshi Tampo, Hajime Shibata, Shinho Kim, Yangdo Kim
Summary: This study presents an effective method of improving the performance of pure sulfide CIGS solar cells through an injection annealing system, which effectively removes secondary phase InSx from the surface of CIGS thin films. As the annealing temperature increases, the open-circuit voltage and fill factor of CIGS devices gradually increase, possibly due to the decrease in bulk defects. Ultimately, a pure sulfide CIGS solar cell with an efficiency of 12.16% was achieved via the injection annealing system.
CURRENT APPLIED PHYSICS
(2021)
Article
Chemistry, Physical
Donghyun Lee, Junghwan Kim, Sang-Kwan Lee, Yangdo Kim, Sang-Bok Lee, Seungchan Cho
Summary: Boron carbide reinforced aluminum alloy composites with continuous multi-interphases were successfully fabricated by stir casting process. The formation of interphases at the B4C/Al6061 interface during the process was consistent with thermodynamic calculations, suggesting possible quantitative compositions of B4C and Al6061 for forming the mentioned interphases.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Materials Science, Multidisciplinary
Byeong Chan Choi, Byoungkoo Kim, Byung Jun Kim, Yong-Wook Choi, Sang Joon Lee, Jong Bae Jeon, Yangdo Kim, Hyoung Chan Kim
Summary: This study investigated the low-temperature fracture behavior of an 80-mm-thick low-carbon steel plate welded by submerged arc. The relationship between impact absorbed energy and ductility-brittle transition temperature (DBTT) was evaluated based on microstructures, with acicular ferrite showing the highest resistance to low-temperature impact among various microstructures in the heat-affected zone.
Article
Materials Science, Multidisciplinary
Yoon-Seok Lee, Shunnosuke Yamagishi, Masataka Tsuro, Changwook Ji, Seungchan Cho, Yangdo Kim, Moonhee Choi
Summary: This study investigated the wear behavior and lubrication effect of AISI304 stainless steel under different lubrication conditions using a block-on-disk wear test. It was found that the oil lubrication demonstrated the best lubricating effect with unique chip-like debris. The observation of strain-induced martensitic (SIM) transformation after the wear test and the influence of lubrication regimes on wear behavior were significant findings from this study.
Article
Chemistry, Multidisciplinary
Chiho Kim, Seunghun Lee, Seong Hyun Kim, Jaehan Park, Shinho Kim, Se-Hun Kwon, Jong-Seong Bae, Yoo Sei Park, Yangdo Kim
Summary: The phosphidation-based synthesis of cobalt-iron-phosphate electrocatalyst shows high activity and durability for hydrogen evolution reaction in alkaline seawater, demonstrating potential for seawater splitting applications. An alkaline seawater electrolyzer utilizing non-precious-metal catalysts achieved better performance and higher solar-to-hydrogen efficiency compared to one using precious metal catalysts.
Article
Electrochemistry
Byeong-Min Ahn, Cheol-Woo Ahn, Byung-Dong Hahn, Jong-Jin Choi, Yang-Do Kim, Sung-Ki Lim, Joon-Hwan Choi
Summary: Sodium-metal chloride batteries are considered high-safety batteries and suitable for battery energy storage systems. This study presents an improved tubular-type simple test cell for accurate analysis of the cathode microstructure. By eliminating external failure factors, the improved test cell exhibits lower capacity gap and longer lifespan, which can advance research in tubular-type sodium-metal chloride batteries in small and academic laboratories.
