• 반도체디스플레이기술학회지
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• 제7권4호
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• pp.41-44
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• 2008

NiSi is less stable than the previously-used $CoSi_2$ at high temperature. Some noble metals, such as Pd and Pt, have been added to NiSi to improve its thermal stability. We employed a first principles calculation to understand the Pd segregation at the interface. An orthorhombic structure of NiSi was used to construct an orthorhombic-NiSi/Si (010). Lattice parameters along a- and c-axes in orthorhombic-NiSi were matched with those of Si for epitaxy contact. The optimized $1\times4\times1$ orthorhombic-NiSi (010) and $1\times2\times1$ Si (010) superstructures were put together to construct the orthorhombic-NiSi/Si (010), and the superstructure was relieved in calculation to minimize its total free energy. The optimized interface thickness of the superstructure was $1.59\AA$. Pd atom was substituted in Ni and Si sites located near interface. Both Ni and Si sites located at the interface were favorable for Pd substitution.

• 한국결정성장학회지
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• 제33권6호
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• pp.261-267
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• 2023

마이크로파 유전체 적용을 위해 (Ca, Sr)(Zr, Ti)O₃ (CSZT) 계에서 MgO 첨가에 따른 결정 구조, 미세 구조, 및 유전 특성을 연구하였다. 고상 반응법을 통해 합성된 CSZT 분말은 orthorhombic 단일상을 형성하였다. CSZT의 시편을 각각 1200℃, 1300℃ 및 1400℃에서 소결하였고, 소결 후 모든 시편은 orthorhombic 단일상을 확인하였다. 또한 모든 소결 시편은 온도가 증가함에 따라 입자 크기가 증가하였다. 1 mol% MgO를 첨가한 시편의 경우도 소결 이후에 orthorhombic 구조를 갖는 것을 확인하였다. EDS 분석을 통해 1400℃에서 소결 중에 이차상이 형성된 것을 확인하였다. MgO 첨가된 CSZT의 입자크기분포와 치밀화는 첨가하지 않은 경우와 거의 유사했으나, 입자크기분포가 좁아지며 균일해지는 것을 확인하였다. MgO 첨가된 CSZT는 1 k Hz에서 ε_r = 34.14, tanδ = 0.00047, τ_ε = -3.58 ppm/℃로 우수한 저손실 유전 특성을 가졌다.

• Journal of Korean Vacuum Science & Technology
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• 제6권4호
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• pp.153-157
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• 2002

The electronic structures of Gd$_{5}$Si$_2$Ge$_2$ compound, which has a giant magnetocaloric effect, in the monoclinic and orthorhombic phases were calculated using the tight-binding linear-muffin-tin-orbital method within the atomic-sphere approximation. The calculated total energies of the monoclinic and orthorhombic structures in the paramagnetic phase confirm that the orthorhombic structure is more stable than monoclinic structure. The density of states (DOS) at the Fermi level of the orthorhombic phase is higher than that of the monoclinic phase in the paramagnetic phase, fulfilling the Stoner criterion. The calculated charge density verified the breaking of Ge(Si)-Ge(Si) bonding in the basal plane upon the orthorhombic-monoclinic phase transition. The DOS curve fairly well reproduces the photoemission spectrum.m.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.107-108
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• 2008

We calculated orthorhombic-NiSi (010)/Si superstructure. Orthorhombic-NiSi was changed to tetragonal structure to be matched with Si substrate. Eight models were produced by the type of Si substrate. In the case of orthorhombic-NiSi (010)/Si (020)[00-1], it was the most favorable energetically and the shortest of the distance between two superstructures. However, in the case of orthorhombic-NiSi (010)/Si (010)[00-1], it was the most unfavorable energetically and the longest of the distance. The energy and distance of orthorhombic-NiSi (010)/Si superstructure were changed by the coordination number of Ni atom and the bond length of atom-atom at the interface.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 춘계학술대회 논문집 초전도 자성체 연구회
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• pp.69-72
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• 2003

Bi-2223 superconducting wires were fabricated by stacking, drawing process with different precursor powders and different heat-treatment histories. The precursor powders were 2 kinds of Pb content. And a part of the tapes were experienced pre-annealing process which caused tetragonal structure of Bi-2212 phase to orthorhombic structure of it was during drawing process. We confirmed the transformation of Bi-2212 phase from tetragonal structure to orthorhombic structure and reduction of second phases. XRD and DC magnetization analysis were performed in order to investigate the fraction of Bi-2223 phase in Bi-2223/Ag HTS tape. We could achieve best Ic of 70 A class at the Bi-2223/Ag tape using low Pb content of precursor powder and experienced pre-annealing process. DC magnetization analysis was useful to investigate the fraction of Bi-2223 phase in the Bi-2223/Ag tape.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2003년도 학술대회 논문집
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• pp.105-108
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• 2003

Long length of Bi-2223 superconducting wires were fabricated by stacking, drawing process with different precursor owders and different heat-treatment histories. The precursor powders were 2 kinds of Pb content. And a part of the tapes were experienced pre-annealing process which caused tetragonal structure of Bi-2212 phase to orthorhombic structure of it was during drawing process. We confirmed the transformation of Bi-2212 phase from tetragonal structure to orthorhombic structure and reduction of second phases. We designed and made a continuous Ic measurement system for Bi-2223/Ag HTS tape. We could achieve best Ic of 65 A at the Bi-2223/Ag tape using low Pb content of precursor powder and experienced pre-annealing process.

• Bulletin of the Korean Chemical Society
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• 제6권4호
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• pp.183-186
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• 1985

The lattice vibrational calculation of orthorhombic hydrogen chloride is performed using physically realistic potential function which can reproduce the X-ray structure and heat of sublimation of the low temperature phase. The polar coordinates representation is introduced in order to describe the intermolecular interactions in a molecular crystal. The splitting in internal modes is calculated as 49 $cm^{-1}$ and the other modes are in good agreement with experimental results.

• Bulletin of the Korean Chemical Society
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• 제16권2호
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• pp.120-125
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• 1995

Solid solutions of Pr2-xBaxNiO4±δ with K2NiF4-type structure were prepared in air and characterized by powder X-ray diffraction, Rietveld refinements, iodometry titrations, and conductivity measurements. The range of the solid solution was 0 ≤ x < 0.5. The crystal structure changes from orthorhombic (Fmmm) for x ≤ 0.1 to pseudo-tetragonal (I4/mmm) for x ≥ 0.2. The orthorhombic structure of x=0.1 transforms to tetragonal at low temperature. The bond distances obtained from the Rietvel analyses did not vary significantly with the Ba content except that of Ni-O (parallel to the c-axis) which showed an abrupt increase from x=0.1 to 0.2. The excess oxygen content (δ) decreases from 0.241 to 0.03 with increasing substituted Ba contents within the solution range. The samples are all semiconductors at the temperature range 4 < T < 300 K.

• 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.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.527-530
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• 2002

A lot of efforts have been focused on the optimization of PIT parameters for Bi-2223/Ag wire. In this paper, initial annealing of Bi-2223/Ag wire to transform Bi-2212 orthorhombic from Bi-2212 tetragonal Precursor was investigated. This initial annealing step at low oxygen partial pressure were to transform Bi-2212 orthorhombic structure and to reduce the formation of second phases at superconducting wire. However Bi-2223 Phases were appeared at higher annealing temperature. Critical currents(Je) of Bi-2223/Ag tapes were sintered at low oxygen Partial pressure were higher than that of the wires sintered at atmosphere condition. In order to investigate the effect of rolling reduction ratio, Bi-2223/Ag HTS tapes were rolled with different reduction ratio. There were no clear difference of Je and filaments shape with various rolling reduction ratio.