• Title, Summary, Keyword: lattices constant

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Electrical Properties of Sintered $HoSi_2$ ($HoSi_2$소결체의 전기적 특성 연구)

  • 이우선;김형곤;김남오
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.14 no.10
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    • pp.792-795
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    • 2001
  • we present a electrical transport(resistivity, Hall effect) measurements in varying temperature ranges between 78K and 300K on HoSi$_2$ composites by hot-pressed sintering. It has been found that this sintered HoSi$_2$ has a orthorhombic structure, and lattices constant is a=9.8545$\AA$, b=7.7935$\AA$, c=7.8071$\AA$. The measured electrical resistivity is about 1.608$\Omega$ cm and carrier mobility is about 6.9$\times$10$^{1}$cm $^{2}$V.sec at low room temperature. The Hall effect shows a n-type conductivity in the sintered HoSi$_2$.

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Updating Algorithms using a Galois-Lattice Structure for Building and Maintaining Object-Oriented Analysis Models (Galois-격자 구조를 이용한 객체지향 분석 모델 구축과 유지에 관한 갱신 알고 리즘)

  • Ahn, Hi-Suck;Jun, Moon-Seog;Rhew, Sung-Yul
    • The Transactions of the Korea Information Processing Society
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    • v.2 no.4
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    • pp.477-486
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    • 1995
  • This paper describes and constructs object-oriented analysis models using Galois-lattices that we are always studying in discrete mathematics, shows fundamental approaches to maintain the models, analyzes the construction of object-oriented analysis models through good examples. Also, we define several properties of Galois-lattices that have binary relations between class objects, propose the incremental updating algorithms that can update the Galois-lattice whenever new classes are added. This proposal shows that in case of adding new class nodes the results from simulations can implement in constant time and have linearly the incremental structures in worst cases, and in that the growth rate of lattices is proportioned to class nodes in time complexity. This results can achieve the high understandability of object-oriented analysis models and the high traceability of maintenance models. Furthermore it is possible to make more efficient performances of class reusability in advantages of object-oriented systems and support truly the class hierarchical maintenances.

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Electrical Properties of (1-x)$CaMnO_{3}-xCaTiO_{3}$Ceramic System ((1-x)$CaMnO_{3}-xCaTiO_{3}$계 세라믹스의 전기적 특성)

  • 안순영;윤상옥;윤종훈;장성식
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.865-868
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    • 2000
  • It was examined that the relationship between microstructures, electrical properties and crystal structure of (1-x)CaMnO$_3$-xCaTiO$_3$solid solution system which was made by mixing a semiconducting material CaMnO$_3$of low resistance and a dielectric material CaTiO$_3$of high resistance with variable ratios (x=0, 0.1, 0.3, 0.5, 0.7, 0.9, 1.0). As the CaTiO$_3$increased, the resistance, B constant and lattice constant were increased, but the grain size was decreased. On particular, above 50wt% of CaTiO$_3$, the resistance at 2 5$^{\circ}C$ was rapidly increased due to the correlation in connectivity of the lattices between the conductive Mn$^{+4}$ octahedron and the insulative Ti$^{+4}$ octahedron.ron.

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Synthesis and Luminescence of Lu3(Al,Si)5(O,N)12:Ce3+ Phosphors

  • Ahn, Wonsik;Kim, Young Jin
    • Journal of the Korean Ceramic Society
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    • v.53 no.4
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    • pp.463-467
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    • 2016
  • $Si^{4+}-N^{3-}$ was incorporated into $Ce^{3+}-doped$ lutetium aluminum garnet ($Lu_{2.965}Ce_{0.035}Al_5O_{12}$, $LuAG:Ce^{3+}$) lattices, resulting in the formation of $Lu_{2.965}Ce_{0.035}Al_{5-x}Si_xO_{12-x}N_x$ [(Lu,Ce)AG:xSN]. For x = 0-0.25, the synthesized powders consisted of the LuAG single phase, and the lattice constant decreased owing to the smaller $Si^{4+}$ ions. However, for x > 0.25, a small amount of unknown impurity phases was observed, and the lattice constant increased. Under 450 nm excitation, the PL spectrum of $LuAG:Ce^{3+}$ exhibited the green band, peaking at 505 nm. The incorporation of $Si^{4+}-N^{3-}$ into the $Al^{3+}-O^{2-}$ sites of $LuAG:Ce^{3+}$ led to a red-shift of the emission peak wavelength from 505 to 570 nm with increasing x. Corresponding CIE chromaticity coordinates varied from the green to yellow regions. These behaviors were discussed based on the modification of the $5d^1$ split levels and crystal field surroundings of $Ce^{3+}$, which arose from the Ce-(O,N)8 bonds.

Electrical properties of sintered $HoSi_2$ ($HoSi_2$ 소결체의 전기적 특성 연구)

  • Lee, Woo-Sun;Oh, Guem-Kon;Kim, Hyung-Gon
    • Proceedings of the KIEE Conference
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    • pp.1396-1398
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    • 2001
  • The $HoSi_2$ compounds prepared by codeposition of Si and Ho, and $HoSi_2$ by sintering method were investigated electrical and Hall effect. The crystal structure of samples showed a orthorhombic structure, and lattices constant is a=9.8545 $\AA$, b=7.7935 $\AA$, c=7.8071 $\AA$. Hall effect shows a n-type conductivity in the sintered $HoSi_2$. The electrical resistivity values was 1.608${\Omega}cm^{-1}$ and carrier mobility was $6.9{\times}10^1cm^2/V{\cdot}sec$ at low room temperature.

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Theoretical Consideration on Influences of Cavity or Pillar Shape on Band Structures of Silicon-Based Photonic Crystals

  • Ogawa, Yoshifumi;Tamura, Issei;Omura, Yasuhisa;Iida, Yukio
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.7 no.1
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    • pp.56-65
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    • 2007
  • This paper describes physical meanings of various influences of cavity (or pillar) shape and filling factor of dielectric material on band structures in two-dimensional photonic crystals. Influences of circular and rectangular cross-sections of cavity (or pillar) arrays on photonic band structures are considered theoretically, and significant aspects of square and triangular lattices are compared. It is shown that both averaged dielectric constant of the photonic crystal and distribution profile of photon energy play important roles in designing optical properties. For the triangular lattice, especially, it is shown that cavity array with a rectangular cross-section breaks the band structure symmetry. So, we discuss this point from the band structure and address optical properties of lattice with a circular cross-section cavity.

Piezoelectric and Ferroelectric Properties of $[Bi_{1-x}(Na_{0.7-x}K_{0.2}Li_{0.1})]_{0.5}Ba_xTiO_3$ Lead-Free Piezoelectric Ceramics (비납계 $[Bi_{1-x}(Na_{0.7-x}K_{0.2}Li_{0.1})]_{0.5}Ba_xTiO_3$ 압전 세라믹의 압전-유전특성)

  • Lee, Dae-Su;Jeong, Soon-Jong;Kim, Min-Su;Park, Eun-Cheol;Song, Jae-Sung
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.271-271
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    • 2006
  • The structural, dielectric and piezoelectric properties of $[Bi_{1-x}(Na_{0.7-x}K_{0.2}Li_{0.1})]_{0.5}BaxTiO_3$ (BNKLBxT) ceramics were studied for the compositional range, x = 0-0.08. The samples were prepared by conventional sintering technique. The result of X-ray diffraction (XRD) suggest that $Ba^{2+}$ diffuse into the $[Bi(Na_{0.7}K_{0.2}Li_{0.1})]_{0.5}TiO_3$ (BNKLT) lattices to form a solid solution with a single phase perovskite structure. The ceramic show excellent piezoelectric and ferroelectric properties, and optimum properties measured are as follows: piezoelectric constant $d_{33}=230pC/N$, planar electromechanical coupling factor $k_p\;=\;40.3%$, remanent polarization $P_r\;=\;30\;{\mu}C/cm^2$, and coercive field $E_c\; =\;2.5\;kV/mm$, respectively.

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Effect of Iron Oxide on the Dielectric and Piezoelectric Properties of (K0.5Na0.5)(Nb0.96Sb0.04)O3Ceramics (Iron Oxide가 (K0.5Na0.5)(Nb0.96Sb0.04)O3 세라믹스의 유전 및 압전특성에 미치는 영향)

  • Seo, Byeong-Ho;Yoo, Ju-Hyun
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.23 no.8
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    • pp.617-621
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    • 2010
  • ($K_{0.5}Na_{0.5}$)($Nb_{0.96}Sb_{0.04}$)$O_3$+1.2 mol% $K_4CuNb_8O_{23}$ ceramics doped with iron oxide ($Fe_2O_3$) were prepared by a conventional mixed oxide method. And then, their piezoelectric and dielectric properties were investigated as a function of $Fe_2O_3$ addition. X-ray diffraction studies reveal that $Fe^{3+}$ diffuses into the NKN lattices to form a solid solution with a pure perovskite structure at room temperature. At the sintering temperature of $1,060^{\circ}C$, when 0.2 mol% $Fe_2O_3$ was doped, the piezoelectric constant ($d_{33}$), electromechanical coupling factor (Kp), and mechanical quality factor ($Q_m$) showed the excellent values of 131.67 pC/N, 0.436, and 696.36, respectively. Results show that $Fe_2O_3$ deped ($K_{0.5}Na_{0.5}$)($Nb_{0.96}Sb_{0.04}$)$O_3$+1.2 mol% $K_4CuNb_8O_{23}$ lead-free piezoelectric ceramics are a promising lead free material for piezoelectric transformer applications.

Fabrication and dielectric properties of $LaAlO_3-BaZrO_3$ perovskites ($LaAlO_3-BaZrO_3$계 perovskites의 제조 및 유전특성)

  • Lee, So-Hee;Kim, Shin;Shin, Hyun-Ho
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.325-325
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    • 2007
  • The perovskites in the $LaAlO_3-BaZrO_3$ system (i.e., $(1-x)LaAlO_3-xBaZrO_3$ were fabricated by a solid state reaction and their dielectric properties were investigated. For the compositions of x=0.1~0.9, the mixture of $LaAlO_3$ with a rhombohedral structure and $BaZrO_3$ with a cubic was observed when the sintering was conducted at $1500^{\circ}C$, indicating that the solubility of constituent elements was very low and a narrow solid solution region might exist. The large difference of ionic radii between $La^{3+}$ ion (0.136nm, C.N.=12) and $Ba^{2+}$ ion (0.161nm) or $Al^{3+}$ ion (0.0535nm, C.N.=6) and $Zr^{4+}$ ion (0.072nm) might hinder the mutual substitution. Within the compositions of x=0~0.7, the dielectric constant of the mixture increased with the amount of $BaZrO_3$, i.e., x value, which was in good agreement with the logarithmic mixing rule (In $_{r,i}={\Sigma}v_iln\;_{r,i}$). The increase in $BaZrO_3$ doping decreased $Q{\times}f$ value significantly due to the low $Q{\times}f$ value of $BaZrO_3$ itself, a poor microstructure of the mixture with an increased grain boundary area per volume, and defects in the cation and oxygen sub-lattices which were respectively caused by the evaporation of barium during the sintering process and the substitution of Ba on La-site or Al on Zr-site.

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The Characteristics of Titanium Disilicide Films following Manufacturing Methods (제조 방법에 따른 Titanium Disilicide 막의 특성)

  • Mo, Man-Jin;Jeon, Bup-Ju;Jung, Il-Hyun
    • Applied Chemistry for Engineering
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    • v.10 no.3
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    • pp.354-361
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    • 1999
  • The films annealed after physical deposition of titanium and chemical deposition of amorphous silicon by plasma were formed Si-rich titanium silicide with a good quality of crystallinity and had the various lattice structures due to orientation of lattices for epitaxy growth during annealing process. Band gap of the titanium silicide had 1.14~1.165 eV and the films annealed after chemical deposition of a-Si:H by plasma were influenced by a-Si and the dangling bond offered by desorption of hydrogen. Urbach tail ($E_0$) of the films annealed after physical deposition of Ti was nearly constant within a range of 0.045~0.05 eV, and the number of defect in films annealed after chemical deposition of a-Si:H by plasma was about 2~3 times more than that in annealed Ti/Si films.

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