• Title/Summary/Keyword: Domain Wall

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Domain formation and expansion during periodic poling of congruent $LiNbO_3$ using external field (조화용융조성 $LiNbO_3$의 주기적 분극 반전 동안 도메인 생성 및 이동에 관한 연구)

  • Kwon, S.W.;Yang, W.S.;Lee, H.M.;Kim, W.K.;Lee, H.Y.;Yoon, D.H.;Song, Y.S.
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.16 no.2
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    • pp.53-58
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    • 2006
  • When external field was applied to congruent $LiNbO_3$, it was investgated for domain formation and expansion of $LiNbO_3$. The domain wall velocities of 0.5 mm thickness $LiNbO_3$ were 28.70, 16.02 and $5.75{\mu}m/sec$ under poling field of 23.5, 22.0 and 21.0 kV/mm, respectively. As $1 M{\Omega}$ resistor was used in domain inversion system, harmonic domain inversion was not achieved by rapid domain expansion. And 50% duty cycle periodically poled $LiNbO_3$ have been fabricated by charge control using $10 M{\Omega}$ resistor.

Magnetization Reversal and Magnetic Switching Volume in Electrodeposited CoPt Magnetic Films with Different Thickness (전기도금법으로 제작한 두께가 다른 CoPt 자성막의 자화역전과 자기역전 부피)

  • Kim, Hyeon-Soo;Jeong, Soon-Young;Lee, Chang-Hyeong;Suh, Su-Jeong
    • Journal of the Korean Magnetics Society
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    • v.21 no.6
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    • pp.193-197
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    • 2011
  • The thickness dependence of the magnetic switching volumes in electrodeposited CoPt films was investigated from the magnetization reversal and the magnetic interaction behavior. As the sample thickness is increased, the field difference between the wall pinning field ($H_{DW}$) and the nucleation field ($H_N$) as well as the absolute value of ${\Delta}$area are increased. Therefore, the decrement tendency of the switching diameter with increasing sample thickness can be well explained by the domain wall motion controlled by the domain wall pinning and the strength of dipolar interaction.

Analytical Study on Hydroelastic Vibration of Stiffened Plate for a Rectangular Tank (사각형 탱크 보강판의 유체구조 연성진동에 대한 이론적 인구)

  • Kim, K.S.;Kim, D.W.;Lee, Y.B.;Choi, B.H.;Choi, S.H.;Kim, Y.S.
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.11b
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    • pp.65-68
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    • 2005
  • In this paper, a theoretical study is carried out on the hydroelastic vibration of a rectangular tank wall. It is assumed that the tank wall is clamped along the plate edges. The fluid velocity potential is used for the simulation of fluid domain and to obtain the added mass due to wall vibration. In addition, the vibration characteristics of stiffened wall of the rectangular tank are investigated. Assumed mode method is utilized to the stiffened plate model and hydrodynamic force is obtained by the proposed approach. The coupled natural frequencies are obtained from the relationship between kinetic energies of a wall including fluid and the potential energy of the wall. The theoretical result is compared with the three-dimensional finite element method and then added mass effect is discussed due to tank length and potential mode.

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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.