• Title/Summary/Keyword: Crystallographic orientation

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The Effected of Amorphous Si Underlayer to Crystallographic Characteristics for Prepared Perpendicular Magnetic Recording Media Thin Film (수직자기기록용 박막의 제작에 있어서 아몰퍼스 실리콘 하지층이 결정학적 특성에 미치는 영향)

  • 박원효;김용진;손인환;가출현;박창옥;김경환
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2002.07a
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    • pp.463-465
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    • 2002
  • In order to increase perpendicular magnetic anisotropy of magnetic layer and prepare magnetic recording layer with a good quality by epitaxial growth between magnetic layer and, we prepared Co$\_$77/Cr$\_$20/Ta$_3$/Si doublelayer for perpendicular magnetic recording media which was promoted as next generation recording media on slide glass substrate. The thickness of magnetic layer and Underlayer were varied from 20 to 100 nm and 5 to 100 m, respectively. The surface morphology and crystal structure of the CoCrTa/Si film were examined with XRD and AFM. Prepared thin films showed improvement of dispersion angle of c-axis orientation Δ$\theta$$\_$50/ caused by inserting amorphous Si underlayer.

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Characterization of SrS:Ag Thin Film Electroluminescence Deposited by Hot Wall Technique (Hot Wall법에 의해 제작한 SrS:Ag 박막EL소자의 특성)

  • Lee, Sang-Tae;Heo, Sung-Gon;Lee, Hong-Chan
    • Proceedings of the Korean Society of Marine Engineers Conference
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    • 2005.11a
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    • pp.242-243
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    • 2005
  • The SrS:Ag, Cl thin films have been grown by the hot wall technique with S furnace placed on the outside of the growth chamber in order to investigate the crystallographic and optical characteristics. The XRD patterns indicate a strongly preferential orientation in the [200] direction. The PL spectrum has an emission peak of about 398nm which is assigned by the transition from $4d^{95}s^1$ to $4d^{10}$ of$Ag^+$ center.

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Anisotropy due to Texture Development in FCC Polycrystals (FCC 다결정재의 집합조직 발전에 따른 이방성의 변화)

  • Kim, Eung-Zu;Lee, Yong-Shin
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.20 no.5
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    • pp.1516-1523
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    • 1996
  • The present study is concerned with the development of anisotropy and deformation texture in polycrystals. The individual grain in an aggregate is assumed to experience the viscoplastic dedformation with crystallographic slip that unsure uniquenessof the active slip systems and shearing rate onthese systems. Two different methods for updating the grain orientation are examined. Texture development for some deformation modes such as plane strain compression, uniaxial tension and simple shear are found. Changes in anisotropic flow potential due to texture development during large deformation are also given. Anisotropic behavior of polycrystals with defferent textures are examined.

The Study of Microstructure Influence at Fretting Contacts using Crystal Plasticity Simulation (결정 소성 시뮬레이션을 이용한 프레팅 접촉에서의 마이크로 구조 영향에 관한 연구)

  • Ko, Jun-Bin;Goh, Chung-Hyun;Lee, Kee-Seok
    • Journal of the Korean Society for Precision Engineering
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    • v.22 no.8 s.173
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    • pp.84-91
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    • 2005
  • The role of microstructure is quite significant in fretting of Ti-6Al-4V since its material properties depend strongly on crystallographic texture. In this study, we adopt crystal plasticity theory with a 2-D planar triple slip idealization to account fur microstructure effects such as grain orientation distribution, grain geometry, as well as $\alpha$ colony size. Crystal plasticity simulations suggest strong implications of microstructure effects at fretting contacts.

Effect of Inductively Coupled Plasma (ICP) Power on the Properties of Ultra Hard Nanocrystalline TiN Coatings (유도결합 플라즈마 파워변화에 따른 초경도 나노결정질 TiN 코팅막의 물성변화)

  • Chun, Sung-Yong
    • Journal of the Korean Ceramic Society
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    • v.50 no.3
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    • pp.212-217
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    • 2013
  • Ultra hard TiN coatings were fabricated by DC and ICP (inductively coupled plasma) magnetron sputtering techniques. The effects of ICP power, ranging from 0 to 300 W, on the coating microstructure, crystallographic, and mechanical properties were systematically investigated with FE-SEM, AFM, HR-XRD and nanoindentation. The results show that ICP power has a significant influence on the coating microstructure and mechanical properties of TiN coatings. With an increasing ICP power, the film microstructure evolves from an apparent columnar structure to a highly dense one. Grain sizes of TiN coatings decreased from 12.6 nm to 8.7 nm with an increase of the ICP power. A maximum nanohardness of 67.6 GPa was obtained for the coatings deposited at an ICP power of 300 W. The crystal structure and preferred orientation in the TiN coatings also varied with the ICP power, exerting an effective influence on film nanohardness.

Finite Element Analysis for Rate-Independent Crystal Plasticity Model (속도 독립성 결정소성모델의 유한요소해석)

  • Ha, Sang-Yul;Kim, Ki-Tae
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.33 no.5
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    • pp.447-454
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    • 2009
  • Rate-independent crystal plasticity model suffers from the non-uniqueness of activated slip systems and the determination of the shear slip rates on the active slip systems. In this paper, a time-integration algorithm which circumvents the problem of the multiplicity of the slip systems was developed and implemented into the user subroutine VUMAT of a commercial finite element program ABAQUS. The magnitude of the slip shears on the active slip systems in f.c.c Cu single crystal aligned with the specific crystallographic orientation was investigated to validate our solution procedure. Also, texture developments under various deformation modes such as simple compression, simple tension and plane strain compression were compared with the results of the rate-dependent model by using the rate-independent crystal plasticity model. The computation time employing the rate-independent model is much more reduced than the those of the rate-dependent model.

Terahertz Emission by LT-GaAs (LT-GaAs에서 테라헬쯔파 방출)

  • Cho, Shin-Ho
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2005.11a
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    • pp.78-79
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    • 2005
  • We report on optically excited terahertz (THz) omission from low-temperature (LT) grown GaAs. We have used 70 fs titanium-sapphire laser pulses with wavelengths at 800 nm to generate THz radiation pulses. The LT-GaAs layers are grown on semi-insulating GaAs substrates with GaAs buffer layer by molecular beam epitaxy (MBE). The THz emission from the LT-GaAs surface is strong and does not show any significant variation in the strength of the THz emission over several different angles between the polarization of the excitation laser pulse and the crystallographic orientation of the LT-GaAs.

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Domain Wall Motions in a Near-Morphotropic PZT during a Stepwise Poling Observed by Piezoresponse Force Microscopy

  • Kim, Kwanlae
    • Korean Journal of Materials Research
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    • v.27 no.9
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    • pp.484-488
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    • 2017
  • In the present study, domain evolution processes of a near-morphotropic PZT ceramic during poling was studied using vertical piezoresponse force microscopy (PFM). To perform macroscopic poling in bulk polycrystalline PZT, poling was carried out in a stepwise fashion, and PFM scan was performed after unloading the electric field. To identify the crystallographic orientation and planes for the observed non-$180^{\circ}$ domain walls in the PFM images, compatibility theory and electron backscatter diffraction (EBSD) were used in conjunction with PFM. Accurate registration between PFM and the EBSD image quality map was carried out by mapping several grains on the sample surface. A herringbone-like domain pattern consisting of two sets of lamellae was observed; this structure evolved into a single set of lamellae during the stepwise poling process. The mechanism underlying the observed domain evolution process was interpreted as showing that the growth of lamellae is determined by the potential energy associated with polarization and an externally applied electric field.

The Crystal Structure of 25,27-Bis(1-propyloxy)-5,11,17,23-tetrakis(1,1-dimethylethy) calix[4]arene-26,28-[(5',6')],(14',15')-dibenzo] crown-7, $C_{70}H_{90}O_9$ (25,27-Bis(1-propyloxy)-5,11,17,23-tetrakis(1,1-dimethylethy) calix[4]arene-26,28-[(5',6')],(14',15')-dibenzo] crown-7, $C_{70}H_{90}O_9$의 결정구조)

  • 김종성;추건홍;이창희;이진호;김문집;김진구;서일환
    • Korean Journal of Crystallography
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    • v.10 no.2
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    • pp.114-118
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    • 1999
  • The title compound consisting of a calix[4]arene molecule with four phenyl rings arranged alter-nately in anti-orientation fashion, two propyloxy groups, and four para-tert-butyl group, attached on the upper rim of calix[4]arene, and polyether chain with two phenyl rings attached on the lower rim of calix[4]arene offers a big cavity inside the molecule that might possess a potential for form-ing host-guest complexes.

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The Crystal Structure of 1,3-Alternate 25,27-Bis(1-propyloxy)calix[4]arene crown-6, $C_{44}H_{54}O_8$ (1,3-Alternate 25,27-Bis(1-propyloxy)calix[4]arene crown-6, $C_{44}H_{54}O_8$의 결정구조)

  • 김종승;이원구;추건홍;이창희;이진호;김문집;김진구;서일환
    • Korean Journal of Crystallography
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    • v.10 no.2
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    • pp.130-135
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    • 1999
  • The title compound consisting of a calix[4]arene molecule with four phenyl rings bridged by four methylene groups and arranged alternately in anti-orientation fashion, two 25,27-bis(1-pro-pyloxy) groups attached on the two lower rims of calix[4]arene, and crown-6 chain attached on the other set of lower rims of calix[4]arene offers a big cavity inside a molecule which might possess a potential for forming host-guest complexes. The molecular packing is accomplished by van der Waals forces.

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