• Title/Summary/Keyword: neutron diffraction

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Structural and Magnetic Properties of Dilute Spinel Ferrites: Neutron Diffractometry and Magnetometry Investigations

  • Mamiya, H.;Terada, N.;Kitazawa, H.;Hoshikawa, A.;Ishigaki, T.
    • Journal of Magnetics
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    • v.16 no.2
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    • pp.134-139
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    • 2011
  • Magnetic properties of highly zinc-substituted manganese ferrites are discussed on the basis of cation distribution. High throughput neutron powder diffractometry indicates that the prepared samples possess a nearly normal spinel structure, where the substitution of nonmagnetic zinc ions mainly causes the dilution of magnetic ions in the A-sublattice and consequently affects bond-randomness in the B-sublattice. On the other hand, the estimated occupancy of manganese ions in the B site indicates that random anisotropy effects due to local Jahn-Teller distortions gradually weaken with the substitution. Bulk magnetometry indicates that the substitution smears the transition from a paramagnetic phase to a soft-magnetic phase. Furthermore, at lower temperatures, such a soft-magnetic phase is destabilized and a magnetic glassy state appears. These features of the magnetic properties of dilute spinel ferrites are discussed from the viewpoint of the above-mentioned various types of disorders.

Effect of Neutron irradiation in $Fe_{81}B_{13.5}_Si{3.5}C_2$Amorphous Ribbon (비정질 $Fe_{81}B_{13.5}_Si{3.5}C_2$ 리본의 중성자 조사에 따른 자기적 특성변화)

  • 김효철;홍권표;김철기;유성초
    • Journal of the Korean Magnetics Society
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    • v.10 no.2
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    • pp.49-52
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    • 2000
  • The changes of magnetic properties in neutron irradiated F $e_{81}$ $B_{13.5}$S $i_{3.5}$ $C_2$ amorphous ribbon were studied by X-ray diffraction, hysteresis loop, temperature dependence of magnetization and complex permeability. The fluences of thermal ( $n_{th}$) and fast ( $n_{f}$) neutron were 6.95$\times$10$^{18}$ $n_{th}$ c $m^{-2}$ and 4.56$\times$10$^{16}$ $n_{f}$c $m^{-2}$ , respectively. The changes of XRD Profiles were not observable at the neutron irradiated sample. The complex permeability spectra showed that the permeability from domain wall motion decreased due to the increase of pinning force against domain motion by the neutron irradiation, and the relaxation frequency of rotational magnetization moved to higher frequency region. The measurement of hysteresis loop showed the increase of magnetic softness, related to rotational magnetization, but saturation magnetization was decreased in neutron irradiation sample. The Curie temperature was decreased in the neutron irradiated sample.e.e.e.

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Introduction to Neutron Scattering for Magnetic Materials Research (자성소재 연구를 위한 중성자산란 입문)

  • Jeong, Jae-Hong;Lee, Sang-Hyun;Park, Je-Geun
    • Journal of the Korean Magnetics Society
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    • v.22 no.3
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    • pp.103-108
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    • 2012
  • Having a de Broglie wavelength of a few ${\AA}$ with its corresponding energies in the range of a few to a few hundreds meV, neutrons are ideally suited for the studies of structure and dynamics in condensed matter research. Neutron scattering has been developed over the past 60 years or so and become a very mature and established experimental technique in the very broad range of material sciences. In this short introductory article, we have explained its working principles and provided few selected examples of application.

Synthesis and Magnetic Properties of Ruddlesden-Popper Phase $(LaSrCa)_3Mn_2O_7$ (Ruddlesden - Popper상 $(LaSrCa)_3Mn_2O_7$의 합성과 자기적 특성에 관한 연구)

  • Song, Min-Seok;Shin, Jin-Hyun;Bae, Chul-Ho;Park, Jung-Hwan;Lee, Jai-Yeoul
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2009.06a
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    • pp.351-352
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    • 2009
  • 이중의 망간 페로브스카이트 블록을 가진 Ruddlesden-Popper 상 (R-P phase) $Sr_3Mn_2O_7$은 공기중에서 불안정하다. 본 연구에서는 Sr이온 자리에 La, Ca이온을 치환함으로써 R-P상을 안정화 시켰으며, 이들의 결정구조는 Neutron Diffraction 데이터를 이용하여 Rietveld 법으로 정밀화하였다 $La_{1.4}Sr_{0.8}Ca_{0.8}Mn_2O_7$, $La_{1.2}Sr_{0.9}Ca_{0.9}Mn_2O_7$$T_N$이 80K이며 25K에서 spin-glass 변이가 관찰되었다.

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Variation of Lattice Constant in Ni-W and Ni-W-Cu Alloys for YBCO Coated Conductor (YBCO 초전도 박막 선재용 Ni-W 및 Ni-W-Cu 합금의 격자상수 변화)

  • Kim Min-Woo;Jung Kyu-Dong;Jun Byung-Hyuk;Kim Hyoung-Seop;Kim Chan-Joong
    • Progress in Superconductivity
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    • v.7 no.1
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    • pp.64-68
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    • 2005
  • We fabricated Ni-based alloy substrates for YBCO coated conductor using powder metallurgy. Tungsten and copper were selected as alloy elements due to their mutual solubility to the base element of nickel. The alloying elements were mixed with nickel using ball milling and dried in air. The powder mixtures were packed in a rubber mold, cold isostatic pressed 200 MPa and made into rods. The compacted rods were sintered at $1150^{\circ}C$ for 6 hours for densification. It was confirmed by neutron diffraction experiment that W and Cu atoms made complete solid solution with Ni. Lattice constant of nickel alloy increased by $0.004{\AA}$ for 1at. $\%$ W in Ni-W alloy, $0.0006{\AA}$ for 1 at. $\%$ Cu in Ni-W-Cu alloy.

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Effect of DyFeO3 Addition on Crystal Structure and Ferrcelectricity of the BiFeO3-PbTiO3 System

  • Kim, Seong-Seog;Kwon, Jong-Uk;Cheon, Chae Il
    • Journal of the Korean Ceramic Society
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    • v.42 no.5 s.276
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    • pp.299-303
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    • 2005
  • The crystal structure and ferroelectricity of the $(1-x)BiFeO_3\;(BF)-xPbTiO_3$ (PT) ceramic system with the addition of $DyFeO_3$ (DF) have been investigated for attaining a high temperature piezoelectric material. This study is focused on the relation between crystal structure and ferroelectric property with the addition of DF over the phase boundary in the (1-x)BF-xPT system. Hysteresis curves of polarization-electric field at room temperature have been measured. The X-ray and neutron diffraction data were analyzed by the rietveld refinement method. The addition of 0.1 mole DF into BF-PT system greatly increases the ferroelectric remanant polarization Pr values, e.g. 17 ${\mu}C/cm^2$ in 0.6BF-yDF-(0.4-y)PT and 31${\mu}C/cm^2$ in 0.5BF-yDF-(0.5.y)PT, respectively. The improved Pr value has been discussed in relation with crystal structure and electrical property.