• 제목/요약/키워드: dysprosium

검색결과 35건 처리시간 0.019초

Dielectric Properties of Orthorhombic Dysprosium Manganites

  • Wang, Wei Tian
    • 한국재료학회지
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    • 제29권12호
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    • pp.753-756
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    • 2019
  • Orthorhombic dysprosium manganite DyMnO3 with single phase is synthesized using solid-state reaction technique and the crystal structure and dielectric properties as functions of temperature and frequency are investigated. Thermally activated dielectric relaxations are shown in the temperature dependence of the complex permittivity, and the respective peaks are found to be shifted to higher temperatures as the measuring frequency increases. In Arrhenius plots, activation energies of 0.32 and 0.24 eV for the high- and low-temperature relaxations are observed, respectively. Analysis of the relationship between the real and imaginary parts of the permittivity and the frequencies allows us to explain the dielectric behavior of DyMnO3 ceramics by the universal dielectric response model. A separation of the intrinsic grain and grain boundary properties is achieved using an equivalent circuit model. The dielectric responses of this circuit are discerned by impedance spectroscopy study. The determined grain and grain boundary effects in the orthorhombic DyMnO3 ceramics are responsible for the observed high- and low-temperature relaxations in the dielectric properties.

Polymer carrier 효과에 의하여 단순화된 새로운 세라믹분말 제조방법 (A preparation of dysprosium monotitanate powder by mixed-oxide ceramics processing employing polymer carrier)

  • 이상진
    • 한국결정성장학회지
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    • 제8권2호
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    • pp.350-355
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    • 1998
  • Ethylene glycol을 polymeric carrier로 사용한 새로운 화학적 세라믹 분말 제조 공정에 의하여 $(Dy_2TiO_5)$ 분말을 제조하였다. Chelation 공정의 생략에도 불구하고, 고순도의 미세한 입자를 갖는 세라믹 분말 제조가 가능함을 확인하였다. 열분석, 미세구조분석, 회절분석 등으로 분말특성을 평가하였다.

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Improvement of Demagnetization by Rotor Structure of IPMSM with Dy-free Rare-Earth Magnet

  • Imamura, Keigo;Sanada, Masayuki;Morimoto, Shigeo;Inoue, Yukinori
    • Journal of international Conference on Electrical Machines and Systems
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    • 제2권2호
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    • pp.141-147
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    • 2013
  • Permanent magnet (PM) motors that employ rare-earth magnets containing dysprosium (Dy) are used in electric and hybrid electric vehicles. However, it is desirable to reduce the amount of Dy used since it is expensive. This study investigates the rotor structure of a PM synchronous motor with a Dy-free rare-earth magnet. Flux barrier shapes and PM thicknesses that enhance the irreversible demagnetization are investigated. In addition, a rotor structure that improves the irreversible demagnetization is proposed. We demonstrate that the proposed rotor structure without Dy improves the irreversible demagnetization.

Void Reactivity of DUPIC Fuel Bundle

  • Hari P. Gupta;Park, Hangbok;Bo W. Rhee;Park, Hyungsoo
    • 한국원자력학회:학술대회논문집
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    • 한국원자력학회 1996년도 춘계학술발표회논문집(1)
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    • pp.52-57
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    • 1996
  • The coolant void reactivity is positive for CANDU reactor loaded with DUPIC fuel which has more fissile content compared to natural uranium. A parametric study was done to reduce the void reactivity of the fuel bundle and loss in discharge burnup was estimated. It is observed that the burnable absorbers like gadolinium, boron, europium are not able to keep the reduction in void reactivity uniform throughout fuel burnup. Dysprosium and erbium can keep the void reactivity reduction uniform throughout. fuel burnup but toss in discharge burnup for erbium case is more compared to that of dysprosium case.

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Dysprosium과 Erbium이 동시 첨가된 X7R MLCC용 페로브스카이트 BaTiO3의 전기적특성과 온도안정성 (Electrical Properties and Temperature Stability of Dysprosium and Erbium Co-doped Barium Titanate with Perovskite Structure for X7R MLCCs)

  • 노태민;김진성;류지승;이희수
    • 한국세라믹학회지
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    • 제48권4호
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    • pp.323-327
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    • 2011
  • The effects of $Dy_2O_3$ and $Er_2O_3$ co-doping on electrical properties and temperature stability of barium titanate ($BaTiO_3$) ceramics were investigated in terms of microstructure and structural analysis. The dielectric constant and the insulation resistance (IR) of 0.7 mol% $Dy_2O_3$ and 0.3 mol% $Er_2O_3$ co-doped dielectrics had about 60% and 20% higher than the values of undoped one, respectively, and the temperature coefficient of capacitance (TCC) met the X7R specification. The addition of $Dy_2O_3$ contributed to electrical properties caused by increase of tetragonality; however, preferential diffusion of $Dy^{3+}$ ions toward A site in $BaTiO_3$ grain exhibited an adverse effect on temperature stability by grain growth. On the other hand, The $Er_2O_3$ addition in $BaTiO_3$ could affect the TCC behavior and the IR with suppression of grain growth caused by reinforcement of grain boundary and electrical compensation. Therefore, the enhanced electrical properties and temperature stability through the co-doping could be deduced from the increase of tetragonality and the suppression of grain growth.

Effects of Dysprosium and Thulium addition on microstructure and electric properties of co-doped $BaTiO_3$ for MLCCs

  • Kim, Do-Wan;Kim, Jin-Seong;Noh, Tai-Min;Kang, Do-Won;Kim, Jeong-Wook;Lee, Hee-Soo
    • 한국재료학회:학술대회논문집
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    • 한국재료학회 2010년도 춘계학술발표대회
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    • pp.48.2-48.2
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    • 2010
  • The effect of additives as rare-earth in dielectric materials has been studied to meet the development trend in electronics on the miniaturization with increasing the capacitance of MLCCs (multi-layered ceramic capacitors). It was reported that the addition of rare-earth oxides in dielectrics would contribute to enhance dielectric properties and high temperature stability. Especially, dysprosium and thulium are well known to the representative elements functioned as selective substitution in barium titanate with perovskite structure. The effects of these additives on microstructure and electric properties were studied. The 0.8 mol% Dy doped $BaTiO_3$ and the 1.0 mol% Tm doped $BaTiO_3$ had the highest electric properties as optimized composition, respectively. According to the increase of rare-earth contents, the growth of abnormal grains was suppressed and pyrochlore phase was formed in more than solubility limits. Furthermore, the effect of two rare-earth elements co-doped $BaTiO_3$ on the dielectric properties and insulation resistance was investigated with different concentration. The dielectric specimens with $BaTiO_3-Dy_2O_3-Tm2O_3$ system were prepared by design of experiment for improving the electric properties and sintered at $1320^{\circ}C$ for 2h in a reducing atmosphere. The dielectric properties were evaluated from -55 to $125^{\circ}C$ (at $1KHz{\pm}10%$ and $1.0{\pm}0.2V$) and the insulation resistance was examined at 16V for 2 min. The morphology and crystallinity of the specimens were determined by microstructural and phase analysis.

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폐 영구자석 스크랩 황산침출용액으로부터 황산나트륨에 의한 희토류 원소 복염침전 거동 고찰 (Double Salt Precipitation Behavior of Rare Earth by Sodium Sulfate in Sulfuric Liquor of Waste Permanent Magnet Scrap)

  • 윤호성;김철주;정경우;김지혜;이은지;유승준
    • 자원리싸이클링
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    • 제26권5호
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    • pp.39-47
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    • 2017
  • 본 연구에서는 희토류 황산수용액으로부터 희토류 원소를 철로부터 분리/회수하고자, 황산나트륨을 이용한 희토류 황산복염 침전반응에 관하여 고찰하였다. 네오디뮴(Nd)은 황산나트륨과 결합하여 복염으로 침전이 용이하게 일어나는 반면에 디스프로슘(Dy)은 황산복염으로 침전되기 위해서 과량의 황산나트륨이 필요하였다. 또한 황산수용액에서 네오디뮴의 존재는 디스프로슘 황산복염 침전을 촉진시켜서 디스프로슘 황산복염 침전률을 증가시켰다. 본 연구에서 사용된 네오디뮴 함량 23.39 mg/ml, 디스프로슘 함량 8.67 mg/ml인 황산수용액으로부터 반응온도 $60^{\circ}C$, 반응 3시간에서 황산나트륨을 7 당량 첨가하였을 때, 네오디뮴 복염 침전률은 99.7%, 디스프로슘 복염 침전률은 94.3%이었다. 또한 네오디뮴과 디스프로슘의 황산복염 침전특성을 이용한 두 원소의 분리 가능성을 고찰한 결과, 염화나트륨 첨가에 의한 염석효과가 디스프로슘 품위 증가에 중요한 역할을 하며 본 연구조건에서 최대 98.7% 품위의 디스프로슘을 얻을 수 있었다.

질소-주게 합성수지를 이용한 U(VI), Cu(II), Dy(III) 이온들의 흡착특성 (Adsorption Characteristic of U(VI), Cu(II), Dy(III) Ions Utilizing Nitrogen-Donator Synthetic Resin)

  • 노기환;김준태;김희정
    • 환경위생공학
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    • 제21권3호
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    • pp.52-60
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    • 2006
  • The ion exchange resins have been synthesized from chlormethyl styrene-1,4-divinylbenzene(DVB) with 1%, 2%, and 20%-crosslinking and macrocyclic ligand of cryptand 21 by copolymerization method and the adsorption characteristics of uranium(VI), copper(II) and dysprosium(III) metallic ions have been investigated in various experimental conditions. The synthesis of these resins was confirmed by content of chlorine, element analysis, and IR-spectrum. The effects of pH, equilibrium time, dielectric constant of solvent and crosslink on adsorption of metallic ions were investigated. The metal ion was showed fast adsorption on the resins above pH 3. The optimum equilibrium time for adsorption of metallic ions was about two hours. The adsorption selectivity determined in ethanol was in increasing order uranium$(UO^{2+}_2)\;>\;copper(Cu^{2+})\;>\;dysprosium(Dy^{3+})$ ion. The adsorption was in order of 1%, 2%, and 20% crosslink resin and adsorption of resin decreased in proportion to order of dielectric constant of solvents.