• Title/Summary/Keyword: lattice parameter

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Formation of Porous Si by Indirect Electrode Anodization (간접전극 양극산화에 의한 다공성 실리콘의 형성)

  • Kim, Soon-Kyu;Chang, Joon-Yeon
    • Journal of the Korean Vacuum Society
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    • v.15 no.3
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    • pp.273-279
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    • 2006
  • This study explored the possibility of porous Si (PS) formed by indirect electrode anodization used for effective isolation material for radio frequency integrated circuits (RFIC). We investigated the effect of current density and reaction time on the porosity size and depth, and X-ray diffraction of bulk Si and porous Si to evaluate the change in lattice parameter. Porosity size and depth usually increases with an increase in the current density and reaction time. PS increases the lattice parameter of Si compared to the bulk Si which causes the compressive stress of around 8 MPa. PS formed by the method is believed to be suitable for isolation material for RFIC because it is simple process as well as good compatibility to Si VLSI process.

Effect of Annealing for YIG Single Crystal Thick Films (YIG 단결정 후막의 열처리의 효과)

  • 김근영;윤석규;김용탁;이성문;윤대호
    • Journal of the Korean Ceramic Society
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    • v.40 no.9
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    • pp.855-858
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    • 2003
  • When the PbO-based flux system is used in the Liquid Phase Epitaxy (LPE) method for Yttrium Iron Garnet (YIG) thick film, the effect of Pb ions incorporated into the grown crystal; increase the lattice parameter, changed the uniaxial magnetic anisotropy constant (Ku) or conductance of grown film. It exerts a bad influence on physical property such as increasing optical absorption of grown film. The content of the Pb ion in crystal was decreased by volatilization of Pb ion after annealing; therefore, the lattice parameter of film was reduced on an average 0.0115 ${\AA}$ by the the Pb ion.

Factors Affecting the Superconducting Transition Temperatures of β-Pyrochlore Oxides AOs2O6 (A=K, Rb and Cs)

  • Jung, Dong-Woon
    • Bulletin of the Korean Chemical Society
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    • v.32 no.2
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    • pp.451-454
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    • 2011
  • The traditional BCS superconductors $AOs_2O_6$ (A=K, Rb, and Cs) were investigated to find the relationship between their structures and superconducting transition temperatures. The $T_c$ decreases with increasing the unit cell parameter of $AOs_2O_6$. This is in contrast to the case of conventional BCS superconductivity in a single bond model, where $T_c$ may increase with increasing the the unit cell parameter since the DOS at Fermi level increases as the unit cell parameter increases. Instead, the $T_c$ of a $\beta$-pyrochlore oxide is proportional to the lattice softness of the compound.

Accuracy Improvement of Lattice Parameters Measured from Electron Diffraction Data (전자회절을 이용한 격자상수의 측정 정확도 향상)

  • Lee, Sang-Gil;Song, Kyung;Kim, Jin-Gyu
    • Applied Microscopy
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    • v.41 no.1
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    • pp.75-79
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    • 2011
  • For quantitative analysis of nano-crystal structure, we reported the accuracy improvement method of lattice parameters measured from electron diffraction. For calculation of Au lattice parameters used as a standard crystal structure, it was considered two different acquisition methods (detector and enegy-filter) and three different calculation methods (conventional, least-square and regression fit). As a result, the measurement reliability could be enhanced by using CCD camera which gives higher performance, while energy-filtering did not affect the improvement the camera constant accuracy. Also, the accuracy of lattice parameters could be improved up to $10^{-4}$ order by regression fitting with correction formula. Finally, it is expected that the combination of regression fitting and intensity extraction from energy-filtered precession electron diffraction gives a solution of quantitative structure analysis for unknown nano-crystals.

Effects of ZrC and VC Addition on the Diffusion Induced Recrystallization of TiC--$Cr_3C_2$ (TiC-$Cr_3C_2$ 계 확산구동 재결정에 미치는 ZrC와 VC 첨가영향)

  • 채기웅
    • Journal of the Korean Ceramic Society
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    • v.33 no.2
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    • pp.223-227
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    • 1996
  • The effect of ZrC and VC addition on the diffusion induced recrystallization (DIR) of TiC-Cr3C2 has been investigated. With in creasing the amount of added ZrC to Cr3C2 the DIR of TiC was suppressed at the begining and then occurred. On the contrary the DIR was accelerated with the addition of VC to Cr3C2 Because the lattice parameters of (Ti, Cr)C and (Ti,V)C are smaller and that of (Ti, Zr)C is larger than that of TiC the lattice parameter of (Ti,Cr,Zr)C is expected to be similar to that of TiC,. The results indicate that the strain energy due to lattice mismatch between TiC and solid-solution carbide is the driving force of the observed energy due to lattice mismatch between TiC and solid-solution carbide is the driving force of the observed DIR.

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Characterization of the biodegradable behavior for biphasic calcium phosphates using X-ray diffraction and lattice parameter (X-선 회절 및 격자 매개변수를 이용한 biphasic calcium phosphate 분말의 생분 해성 특성평가)

  • Kim, Dong-Hyun;Song, Chang-Weon;Kim, Tae-Wan;Jin, Heoyng-Ho;Park, Hong-Chae;Yoon, Seog-Young
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.21 no.4
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    • pp.169-174
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    • 2011
  • Nanoscale-biodegradable behaviors of synthesized biphasic calcium phosphates (BCP) powders were characterized using X-ray diffraction (XRD), lattice parameter, and field emission microscopy (FE-SEM). The calcined BCP powders in vitro tested in Hank's balanced salt solution (pH = 7.4, $36.5^{\circ}C$) for 3 weeks. The calculated unit cell parameters for BCP have shown lattice distortion and expansion as irregular changes in the a and c-axis after in vitro.

Lattice based Microstructure Evolution Model for Monte Carlo Finite Element Analysis of Polycrystalline Materials (격자식 미세구조 성장 모델을 이용한 다결정 박막 소재의 유한 요소 해석)

  • 최재환;김한성;이준기;나경환
    • Transactions of Materials Processing
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    • v.13 no.3
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    • pp.248-252
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    • 2004
  • The mechanical properties of polycrystalline thin-films, critical for Micro-Electro-Mechanical Systems (MEMS) components, are known to have the size effect and the scatter in the length scale of microns by the numbers of intensive investigation by experiments and simulations. So, the consideration of the microstructure is essential to cover these length scale effects. The lattice based stochastic model for the microstructure evolution is used to simulate the actual microstructure, and the fast and reliable algorithm is described in this paper. The kinetics parameters, which are the key parameters for the microstructure evolution based on the nucleation and growth mechanism, are extracted from the given micrograph of a polycrystalline material by an inverse method. And the method is verified by the comparison of the quantitative measures, the number of grains and the grain size distribution, for the actual and simulated microstructures. Finite element mesh is then generated on this lattice based microstructure by the developed code. And the statistical finite element analysis is accomplished for selected microstructure.

Magnetic Properties of La-doped YIG Films Prepared by LPE(Liquid Phase Epitaxy) (LPE 성장법으로 성장시킨 La을 첨가한 YIG 막의 자성특성)

  • 김동영;한진우;김명수;이상석
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.14 no.3
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    • pp.257-262
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    • 2001
  • Single crystalline films of La doped YIG(yttrium iron garnet) were grown by the liquid phase epitaxy. The lattice constants of films obtained by DCD(double crystalline diffractometer) measurement increased with increasing La contents in films. In particular, lattice constants of films grown wiht Y/La=20 solution were nearly same as those of GGG (gadolinium gallium garnet) substrate. The saturation magnetization measured with VSM (vibrating sample magnetometer) was about 1750Gauss which is the same as that of pure YIG irrespective of La contents in films. FMR(ferromagnetic resonance) linewidth of La doped YIG was smaller than that of pure YIG. Since appropriate La doping decreases the lattice mismatch between film and substrate, the FMR linewidth was Y/La=20 in this experiment.

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Lattice strain effects on superconductivity in $La_{2-x}Sr_{x}CuO_{4}$ single-crystalline films grown by IR-LPE technique

  • Tanaka, I.;Islam, A.T.M.N.;Wataudhi, S.
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.13 no.4
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    • pp.172-175
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    • 2003
  • We have investigated effects of the lattice mismatch between the LPE films and the substrates. We have grown $La_{2-x}Sr_{x}CuO_{4}$(x=0.1 to 0.15) single crystalline films on single crystalline substrates having different lattice parameter ratio c/a e.g., $La_{2-x}Sr_{x}Cu_{1-y}Zn_{y}O_{4},\;La_{2-x}Ba_{x}CuO_{4},\; LaSrAlO_{4}\;and\;La_{2-x}Sr_{x}Cu_{1-y}Al_{y}O_{4}$ etc., using the IR-LPE technique. The superconducting properties of the grown films were found to vary significantly depending on the lattice mismatch with different substrates.

A Strategy for Phase Identification of Precipitates in High Al-containing Austenitic and Ferritic Steels Using Electron Diffraction

  • Heo, Yoon-Uk
    • Applied Microscopy
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    • v.44 no.4
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    • pp.144-149
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    • 2014
  • A strategy for phase identification of precipitates in high Al-containing austenitic and ferritic steels using electron diffraction (ED) is studied. Comparative studies of the various Al-containing precipitates (k-carbide, $Ni_3Al$, $Fe_3Al$, FeAl) show the similarities of crystal structure and lattice parameter. However, the slight differences of lattice parameter and structure display characteristic ED patterns (EDPs) which can be identified. $L1_2$ k-carbide and $Ni_3Al$ can be differentiated by the length of ${\rightarrow}_g$ (the reciprocal lattice vector), even though they show perfectly identical shapes of EDPs. $DO_3$ $Fe_3Al$ and $B_2$ FeAl show the characteristic EDs in [110] and [112] beam directions due to the differences of Fe site occupancies in unit cells. k-carbide, $Ni_3Al$, and FeAl show also the similar EDs in [112], [112], and [110] beam directions, respectively. All the possible similarities of EDs among each phases and the strategy for phase identification are discussed on the bases of kinematical ED simulation.