• 제목/요약/키워드: Rare Earth

검색결과 974건 처리시간 0.024초

A New Type of CPPM Machine with Stator Axial Magnetic Ring

  • Xie, Kun;Li, Xinhua;Ma, Jimin;Wu, Xiaojiang;Yi, Hong;Hu, Gangyi
    • Journal of Electrical Engineering and Technology
    • /
    • 제13권3호
    • /
    • pp.1285-1293
    • /
    • 2018
  • This paper proposes a new type of consequent-pole permanent-magnet (CPPM) machine with stator axial magnetic ring that increases torque capability over a wide speed range and enhances efficiency for the built-in rare-earth permanent magnet synchronous machine used in new energy vehicles. The excitation winding of the CPPM hybrid excitation synchronous machine in the stator is replaced by ferrite magnetic ring to simplify the structure and manufacturing process of the machine. The basic structure and magnetic regulation principle of the proposed machine are introduced and compared with the traditional interior rare-earth permanent magnet synchronous machine and CPPM hybrid excitation synchronous machine. Finally, experimental results of a new type of CPPM synchronous motor prototype with axial magnetic ring are introduced in the paper.

MAGNETIC PROPERTIES OF $REPb_{2}$(RE: LIGHT RARE-EARTH ELEMENT) COMPOUNDS

  • Hattori, Y.;Sugioka, R.;Fukamichi, K.;Suzuki, K.;Goto, T.
    • 한국자기학회지
    • /
    • 제5권5호
    • /
    • pp.753-757
    • /
    • 1995
  • Systematic studies on the crystal structure and magnetic properties of light rare earth element(RE) compounds with Pb, $REPb_{2}$, have been carried out. Their crystal structure has been identified to be a $MoSi_{2}$-type. The values of the effective magnetic moment for $CePb_{2},\;PrPb_{2}\;and\;NdPb_{2}$ are respectively very close to the theoretical values of $RE^{3+}$. These three compounds are antiferromagnetic and exhibit a metamagnetic transition. The magnitude of the Neel temperature is proportional to two-thirds of the de Gennes factor. The magnetic entropy change for $NdPb_{2}$ is contrast to the value for $CePb_{2}$ heavy-fermion compound, comparable to the theoretical value. The magnetic contribution to the temperature dependence of resistivity for $PrPb_{2}$ is given by a form of -lnT in a wide temperature range, implying the Kondo system in analogy with $Cepb_{2}$.

  • PDF

ANISOTROPY CONSTANTS OF $(Sm_{0.5}RE_{0.5})Fe_{11}Ti$ COMPOUNDS (RE=RARE EARTH)

  • Kim, H.T.;Kim, Y.B.;Park, W.S.;Kim, C.S.;Kim, T.K.;Jin, Han-Min
    • 한국자기학회지
    • /
    • 제5권5호
    • /
    • pp.683-686
    • /
    • 1995
  • Using by the x-ray diffractometry(XRD), the thermomagnetic analysis(TMA), a scanning electron microscopy (SEM-EDX), we knew that the $(Sm_{0.5}RE_{0.5})Fe_{11}Ti$ (RE=Ce,Pr,Nd,Sm,Gd,Tb) compounds were formed to tetragonal $ThMn_{12}$-type structure having a uniaxial magnetocrystalline anisotropy with easy magnetization c-axis. The intrinsic magnetic properties of those were determined by fitting the two magnetization curves of experimental and calculation magnetization. The anisotropy constant $K_{1}$ of this compounds was in the range of $1.75\;-\;9.2\;MJ/m^{3}$ and approximately one order higher than $K_{2}$. $SmFe_{11}Ti$ had the highest anisotropy of $K_{1}\;=\;9.2\;MJ/m^{3}$, $K_{2}\;=\;0.4\;MJ/m^{3}$ and ${\mu}_{o}H_{A}=\;19.8\;T$ among the compounds, substitution of any other rare earth elements for Sm decreased magnetocrystalline anisotropy.

  • PDF

반강자성 물질의 자기변형 (Magnetostriction in Antiferromagnetic Systems)

  • 김창근;김범현;민병일
    • 한국자기학회지
    • /
    • 제18권4호
    • /
    • pp.159-162
    • /
    • 2008
  • 자기변형(magnetostriction) 현상은 외부 온도와 자기장이 변할 때 자성체의 모양이나 부피가 변하는 현상이다. 반강자성을 갖는 희토류 원소와 화합물에서의 관측되는 자기변형 현상은 결정장에 의한 결정장 변형(crystal-field striction)과 교환상호작용에 의한 교환 변형(exchange striction)으로 잘 설명할 수 있음이 알려져 있다. 이 해설 논문에서는 결정장과 교환 상호작용을 포함하는 자기변형 표준이론에 대하여 논의하고자 한다.

Monte Carlo simulation and study of REE/PET composites with wide γ-ray protection

  • Tongyan Cui;Ruixin Chen;Shumin Bi;Rui Wang;Zhongjian Ma;Qingxiu Jia
    • Nuclear Engineering and Technology
    • /
    • 제55권8호
    • /
    • pp.2919-2926
    • /
    • 2023
  • In this paper, rare earth element (REE)/polyester composites were designed with lanthanum oxide, gadolinium oxide, and lutetium oxide as ray shielding agents, and polyethylene terephthalate (PET) as the base. Monte Carlo simulation was carried out using FLUKA software. We found that the radiation protection performance of the composite is affected by the type and amount of REE; a higher amount of REE equated to a better radiation protection performance of the composite. When the thickness of the composite and total thickness of the REE is constant, the number of superimposed layers inside the composite does not affect its shielding performance. Compared with a single-type REE/PET composite, a mixed-type REE/PET composite has a wider range of γ-ray absorption and better radiation protection performance. When the mass ratio of PET to REE is 2:8 and different types of REE are mixed with equal mass, several 0.2 cm-thick mixed-type REE/PET composites can shield >70% of 60 and 80 KeV γ-rays.

산화물 반도체 가스 센서의 습도 의존성 제거 기술 (Humidity Dependence Removal Technology in Oxide Semiconductor Gas Sensors)

  • 박지호;윤지욱
    • 한국전기전자재료학회논문지
    • /
    • 제37권4호
    • /
    • pp.347-357
    • /
    • 2024
  • Oxide semiconductor gas sensors are widely used for detecting toxic, explosive, and flammable gases due to their simple structure, cost-effectiveness, and potential integration into compact devices. However, their reliable gas detection is hindered by a longstanding issue known as humidity dependence, wherein the sensor resistance and gas response change significantly in the presence of moisture. This problem has persisted since the inception of oxide semiconductor gas sensors in the 1960s. This paper explores the root causes of humidity dependence in oxide semiconductor gas sensors and presents strategies to address this challenge. Mitigation strategies include functionalizing the gas-sensing material with noble metal/transition metal oxides and rare-earth/rare-earth oxides, as well as implementing a moisture barrier layer to prevent moisture diffusion into the gas-sensing film. Developing oxide semiconductor gas sensors immune to humidity dependence is expected to yield substantial socioeconomic benefits by enabling medical diagnosis, food quality assessment, environmental monitoring, and sensor network establishment.

마그네슘 합금의 고온 평면변형 압축에서 Pb 첨가에 따른 미세조직 및 집합조직 변화 (Effects of Pb Aaddition on Microstructur and Texture in High Temperature Plane Strain Compression of Magnesium Alloys)

  • 지예빈;윤지민;김권후
    • 열처리공학회지
    • /
    • 제37권1호
    • /
    • pp.23-28
    • /
    • 2024
  • As global warming accelerates, the transportation industry is increasing the use of lightweight materials with the goal of reducing carbon emissions. Magnesium is a suitable material, but its poor formability limits its use, so research is needed to improve it. Rare-earth elements are known to effectively control texture development, but their high cost limits commercial. In this study, changes in microstructure and texture were investigated by adding Pb, which is expected to have a similar effect as rare-earth elements. The material used is Mg-15wt%Pb alloy. Initial specimens were obtained by rolling at 773 K to a rolling reduction of 25% and heat treatment. Afterwards, plane strain compression was performed at 723 K with a strain rate of 5×10-2s-1 and a strain of -0.4 to -1.0. As a result, recrystallized grains were formed within the microstructure, and the main component of the texture changed from (0,0) to (30,26). The maximum axial density was initially 10.01, but decreased to 4.23 after compression.

충남탄전, 대동누층군의 셰일과 탄질암에 관한 암석화학 및 환경지구화학적 특성 (Petrochemistry and Environmental Geochemistry of Shale and Coal from the Daedong Supergroup, Chungnam Coal Field, Korea)

  • 이찬희;이현구;김경웅
    • 자원환경지질
    • /
    • 제30권5호
    • /
    • pp.417-431
    • /
    • 1997
  • Characteristics of sedimentary rocks and enrichment of toxic elements in shale and coal from the Chungnam coal field were investigated based upon geochemistry of major, trace and rare earth elements. Shale and coal of the area are interbedded along the Traissic to the Jurassic Daedong Supergroup, which can be subdivided into grey shale, black shale and coal. The coal had been mined, however all the mines are abandonded due to the economic problems. The shale and coal are characterized by relatively low contents of $SiO_2$, and $Al_2O_3$ and high levels of loss-on-ignition (LOI), CaO and $Na_2O$ in comparison with the North American Shale Composite (NASC). Light rare earth elements (La, Ce, Yb and Lu) are highly enriched with the coal. Ratios of $Al_2O_3/Na_2O$ and $K_2O/Na_2O$ in shale and coal range from 30.0 to 351.8 and from 4.2 to 106.8, which have partly negative correlations against $SiO_2/Al_2O_3$ (1.24 to 6.06), respectively. Those are suggested that controls of mineral compositions in shale and coal can be due to substitution and migration of those elements by diagenesis and metamorphism. Shale and coal of the area may be deposited in terrestrial basin deduced from high C/S (39 to 895) and variable composition of organic carbon (0.39 to 18.40 wt.%) and low contents of reduced sulfur (0.01 to 0.05 wt.%). These shale and coal were originated from the high grade metamorphic and/or igneous rocks, and the rare earth elements of those rocks are slightly influenced with diagenesis and metamorphism on the basis of $Al_2O_3$ versus La, La against Ce, Zr versus Yb, the ratios of La/Ce (0.38 to 0.85) and Th/U (3.6 to 14.6). Characteristics of trace and rare earth elements as Co/Th (0.07 to 0.86), La/Sc (0.31 to 11.05), Se/Th (0.28 to 1.06), V/Ni (1.14 to 3.97), Cr/V (1.4 to 28.3), Ni/Co (2.12 to 8.00) and Zr/Hf (22.6~45.1) in the shale and coal argue for inefficient mixing of the simple source lithologies during sedimentation. These rocks also show much variation in $La_N/Yb_N$ (1.36 to 21.68), Th/Yb (3.5 to 20.0) and La/Th (0.31 to 7.89), and their origin is explained by derivation from a mixture of mainly acidic igneous and metamorphic rocks. Average concentrations in the shale and coal are As=7.2 and 7.5, Ba=913 and 974, Cr=500 and 145, Cu=20 and 26, Ni=38 and 35, Pb=30 and 36, and Zn=77 and 92 ppm, respectively, which are similar to those in the NASC. Average enrichment indices for major elements in the shale (0.79) and coal (0.77) are lower than those in the NASC. In addition, average enrichment index for rare earth elements in coal (2.39) is enriched rather than the shale (1.55). On the basis of the NASC, concentrations of minor and/or environmental toxic elements in the shale and coal were depleted of all the elements examined, excepting Cr, Pb, Rb and Th. Average enrichment indices of trace and/or potentially toxic elements (As, Cr, Cu, Ni, Pb, U and Zn) are 1.23 to 1.24 for shale and 1.06 to 1.22 for coal, respectively.

  • PDF

음이온교환수지에 의한 모나자이트 중 희토류원소의 분리 (제2보) (Separation of Rare Earth Elements in Monazite Sand by Anion Exchange Resin (Ⅱ))

  • 차기원;이종해;윤석호;하영구
    • 대한화학회지
    • /
    • 제24권6호
    • /
    • pp.452-456
    • /
    • 1980
  • 용리액의 pH와 EDTA 농도변화에 따른 모나자이트 중의 희토류원소의 분리에 이어 수지통의 크기, 유츌속도 수지종류에 따른 분리를 약 10g 의 희토류를 흡착시킨 후 연구하였다. 같은 무게의 수지에서는 수지통의 높이가 높은 것이 낮은 것보다 분리도가 좋았고, 전 희토류를 용리하는데 필요한 용리액의 부피는 비슷하였다. 용리액의 유출속도를 1ml/min에서 2ml/min으로 증가시킨 결과 전 희토류를 완전히 용리시키는데 필요한 용리액의 부피가 10l 더 필요했고 분리도는 1ml/min일때 보다 나빴다. 그러나 용리시키는데 걸리는 시간은 약 6일 단축되었다. 수지의 입자가 25∼50 mesh의 Ambellite IR A-400의 수지를 이용하여 분리한 결과는 Dowex 1(50∼100 mesh)의 수지를 사용하여 분리한 결과보다 못하였다.

  • PDF

해외 금속자원에 대한 광상유형별 자료 분석을 통한 효과적인 자원개발 (The Optimal Resource Development for Analysing Data of Deposit Types' Ore Reserves of Oversea Metal Resource)

  • 유봉철;이종길;이길재;이현구
    • 자원환경지질
    • /
    • 제41권6호
    • /
    • pp.773-795
    • /
    • 2008
  • 우리나라의 주요 수입 광종은 동광, 연-아연광, 철광, 망간광 및 몰리브덴광 등이다. 우리나라의 해외자원개발은 아시아 14개국 92개 사업, 미주 및 유럽지역 10개국 29개 사업 그리고 중동 및 아프리카 9개국 14개 사업이 있으며 주로 호주, 중국, 몽골 및 인도네시아에서 사업수가 높다. 호주, 인도네시아 및 중국의 사업은 대부분이 석탄이고 일부 망간, 철, 연-아연, 니켈, 구리, 금, 몰리브덴, 희유원소 및 우라늄 등이나 몽골은 금과 희유원소가 큰 부분을 차지한다. 금속자원에 대한 광상 유형별 대표적인 광상형은 조산 lode형 광상, VMS형 광상, 반암형 광상, SEDEX형 광상, MVT형 광상, IOCG형 광상 및 마그마성 Ni-Cu-PGE형 광상 등이 있으며 이들 유형별 광상들은 전세계적으로 도처에 분포하며 다른 유형별 광상보다 금속자원의 매장량이 높고 부산물인 미량 금속자원에 대한 품위도 높게 나타난다. 따라서 향후 해외광물자원의 탐사 및 개발에 있어 우선 각 국가별 매장량, 주요 광물자원의 생산량 및 지체구조와 함께 광상 유형별 등을 종합 검토하여 조사 및 탐사를 실시한다면, 해외자원개발의 투자 위험도가 감소될 뿐만 아니라 탐사대상지역에서 품위가 높은 광체를 확보할 수 있을 것이다.