• Title, Summary, Keyword: P-E hysteresis

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A Study on the Development of a System for Measuring Dielectric Hysteresis (유전 히스테리시스 특성 측정장치의 연구 개발)

  • 강대하
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.12 no.1
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    • pp.58-68
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    • 1998
  • A computer-controlled system for measuring dielectric hysteresis has been developed. This system consists of the wave generation par\, the high voltage amplifier part, the measurement part, the data acquisition part and the related controll circuits and is interfaced to P.C(personal computer). The applied voltage and its frequency are controlled by P.C . Since the measured datas can be saved in the RAM of P.C, the analysis and the graphics of the datas are very convenient. As a accuracy test, the capcitances of the commercial mica and styroll capacitors were measured by applying high voltage and the results were good agreement with the rating values. In the test of PZT ceramic sample, the typical D-E hysteresis loops were obtained by applying a single frequency voltage to the sample, and $\varepsilon-E$ and D-E hysteresis loops could be measured at the same time by applying a double frequency voltage to the sample.sample.

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Study on the Shift in the P-E Hysteresis Curve and the Fatigue Behavior of the PZT Capacitors Fabricated by Reactive Sputtering (반응성 스퍼터링법으로 형성시킨 PZT 커패시티의 P-E 이력곡선의 이동현상 및 피로 특성 연구)

  • Kim, Hyun-Ho;Lee, Won-Jong
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.18 no.11
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    • pp.983-989
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    • 2005
  • [ $PZT(Pb(Zr,Ti)O_3)$ ] thin films were deposited by multi-target reactive sputtering method on $RuO_2$ substrates. Pure perovskite phase PZT films could be obtained by introducing Ti-oxide seed layer on the $RuO_2$ substrates prior to PZT film deposition. The PZT films deposited on the $RuO_2$ substrates showed highly voltage-shifted hysteresis loop compared with the films deposited on the Pt substrates. The surface of $RuO_2$ substrate was found to be reduced to metallic Ru in vacuum at elevated temperature, which caused the formation of oxygen vacancies at the initial stage of PZT film deposition and gave rise to the voltage shift in the P-E hysteresis loop of the PZT capacitor. The fatigue characteristics of the PZT capacitors under unipolar wane electric field were different from those under bipolar wane. The fatigue test under unipolar wane showed the increase of polarization. It was thought that the ferroelectric domains which had been pinned by charged defects such as oxygen vacancies and the charged defects were reduced in number by combining with the electrons injected from the electrode under unipolar wave, resulting in the relaxation of the ferroelectric domains and the increase of polarization.

Ferroelectric Properties of Ti-Doped and W-Doped SBT Ceramics (Ti와 W이 첨가된 SBT 세라믹스의 강유전 특성)

  • 천채일;김정석
    • Journal of the Korean Ceramic Society
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    • v.41 no.5
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    • pp.401-405
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    • 2004
  • Undoped SrB $i_2$T $a_2$O$_{9}$, donor-doped Sr$_{0.99}$B $i_2$(Ta$_{0.99}$W$_{0.01}$)$_2$O$_{9}$ and acceptor-doped SrB $i_2$(Ta$_{0.99}$Ti$_{0.01}$)$_2$O$_{8.99$ ceramics were prepared and their microstructure, ferroelectric P-E hysteresis and Curie temperature were investigated. Grain size did not influence P-E hysteresis curve in undoped SrB $i_2$T $a_2$O$_{9}$ ceramics. Donor-Doped Sr$_{0.99}$B $i_2$(Ta$_{0.99}$W$_{0.01}$)$_2$O$_{9}$ ceramics showed more saturated P-E hysteresis curve with larger remanent polarization (P$_{r}$) than undoped SrB $i_2$T $a_2$O$_{9}$ ceramics while acceptor-doped SrB $i_2$(Ta$_{0.99}$Ti$_{0.01}$)$_2$O$_{8.99}$ ceramics led to a pinched P-E hysteresis loop. Larger polarization in donor-doped Sr$_{0.99}$B $i_2$(Ta$_{0.99}$W$_{0.01}$)$_2$O$_{9}$ ceramics resulted from easier domain wall motion by Sr-vacancies.

Dielectric Dispersion and Ferroelectric P-E Hysteresis Loop of Lead-Free Ta-Substituted (Na0.53K0.47)(Nb0.55Ta0.45)O3 Ceramics (Ta이 치환된 (Na0.53K0.47)(Nb0.55Ta0.45)O3 무연세라믹의 저주파수 유전분산과 강유전 P-E 이력특성)

  • Kim, Jin Soo;Kim, Hyo-Eun;Lee, Ho Sueb;Lee, Kwang-Sei
    • New Physics: Sae Mulli
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    • v.67 no.11
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    • pp.1284-1290
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    • 2017
  • Ta-substituted $(Na_{0.53}K_{0.47})(Nb_{0.55}Ta_{0.45})O_3$ (NKNT) ceramics were prepared by using a solid-state reaction method. We studied the dielectric response and the ferroelectric P-E hysteresis loop. The $T_{O-T}$ (orthorhombic-tetragonal) and $T_c$ (tetragonal-cubic) phase transitional temperatures decreased, and the piezoelectric properties of NKNT were enhanced. In addition, the low-frequency dispersion decreased, and the ferroelectric P-E hysteresis loops became saturated. We discuss the low-frequency dielectric response and the ferroelectric properties related to the formation of defects, as well as the contribution of charge carriers.

Core Loss Analysis of Non-oriented Electrical Steel Under Magnetic Induction Including Higher Harmonics

  • Cho, Chuhyun;Son, Derac;Cho, Youk
    • Journal of Magnetics
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    • v.6 no.2
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    • pp.66-69
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    • 2001
  • The actual magnetic induction waveform of cores in electrical machines is not sinusoidal i.e. higher harmonics are always included. Thus the core loss in actual electrical machines is different from the core loss which is measured by the standard method, because the waveform of magnetic induction should be sinusoidal in the standard testing method. Core loss analysis under higher harmonic induction is always important in electric machine design. In this works we measured the core loss when a hysteresis loop has only one period of an ac minor loop of higher harmonic frequency, depending on the position of the ac minor loop of relative to the fundamental harmonic frequency. From this experiment, the core loss P(B/sub 0/f/sub 0/, B/sub h/, nf/sub 0/)) under a higher harmonic magnetic induction B/sub h/ could be expressed by the linear combination the core loss at fundamental harmonic frequency P/sub c/(B/sub 0/, f/sub 0/), the core loss of ac minor loop at zero induction region of the major hysteresis loop P/sub cL/ (B/sub h/, nf/sub 0/), and the core loss of an ac minor loop in the high induction region of the major hysteresis loop P/sub cH/ (B/sub h/, nf/sub 0/) i.e., P/sub c/, (B/sub 0/, f/sub 0/, B/sub h/, nf/sub 0/)=P/sub c/ (B/sub 0/, f/sub 0/,)+(n-1)[k₁(B/sub 0/) P/sub cL/ (B/sub h/, nf/sub 0/)+(1-k₁(B/sub 0/)) P/sub cH/ (B/sub h/, nf/sub 0/)]. This will be useful formula for electrical machine designers and one of effective methods to predict core loss including higher harmonic induction.

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A New Technique for Partial Discharge Signal Detection in Oil using Op (광학적 방법을 이용한 유중 부분방전 신호 검출을 위한 신기술 개발)

  • Choi, S.S.;Kang, W.J.;Chang, Y.M.;Lee, J.H.;Kim, J.T.;Koo, J.Y.
    • Proceedings of the KIEE Conference
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    • pp.1705-1707
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    • 1997
  • In this work, a possible new PD de technique, based on the electro-optic effect(P effect), has been proposed. The refractive index ellipsoid of EO crystal, as $LiNbO_3$, is changed by both the externally a electric field and its hysteresis loop of which effect on this hysteresis loop gives rise t discrepancy of index variation. Therefore, an eq regarding the phase variation of modulated beam through $LiNbO_3$ crystal under applied e field, is newly proposed considering the influen hysteresis characteristics. For this purpose generated from needle-plane electrode in oil has detected by use of $LiNbO_3$ cell and analyzed b equation. As a result, it is observed that PD measu phase intervals are limited by the cr characteristics such as asymmertrical P-E hyst and half-wave voltage.

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Dielectric Properties and Electrocaloric Effects of PLZT Ferroelectric Ceramics by Applying Electric Fields (전계 인가에 따른 PLZT 강유전체의 유전특성 및 전기열량 효과)

  • Kim, You-Seok;Yoo, Ju-Hyun;Jeong, Yeong-Ho
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.29 no.3
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    • pp.164-167
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    • 2016
  • In this study, in order to develop relaxor ferroelectric ceramics for refrigeration device application with large electrocaloric effect, PLZT(8/65/35) composition was fabricated using conventional solid-state method. The Curi temperature of this composition PLZT ceramics was $230^{\circ}C$, and the P-E hysteresis loops of the PLZT ceramics as a fuction of temperature became slim by degrees with higher temperatures. The maximum value of ${\Delta}T$ of $0.243^{\circ}C$ in ambient temperature of $215^{\circ}C$ with 30 kV/cm was appeared. It is considered that PLZT ceramics possess the possibility of refrigeration device application.

Effects of Remanent Polarization State and Internal Field in Ferroelctric Film on the Hydrogen-induced Degradation Characteristics in Pt/Pb(Zr, Ti)O3/Pt Capacitor (강유전막의 잔류 분극 상태와 내부 전계가 Pt/Pb(Zr,Ti)O3/Pt 커패시터의 수소 열화 특성에 미치는 영향)

  • Kim, Dong-Cheon;Lee, Gang-Un;Lee, Won-Jong
    • Korean Journal of Materials Research
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    • v.12 no.1
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    • pp.75-81
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    • 2002
  • The ferroelectric properties of Pb(Zr,Ti)O$_3$[PZT] films degrade when the films with Pt top electrodes are annealed in hydrogen containing environment. This is due to the reduction activity of atomic hydrogen that is generated by the catalytic activity of the Pt top electrode. At the initial stage of hydrogen annealing, oxygen vacancies are formed by the reduction activity of hydrogen mainly at the vicinity of top Pt/PZT interface, resulting in a shift of P-E (polarization-electric field) hysteresis curve toward the negative electric field direction. As the hydrogen annealing time increases, oxygen vacancies are formed inside the PZT film by the inward diffusion of hydrogen ions, as a result, the polarization degrades significantly and the degree of P-E curve shift decreases gradually. The direction and the magnitude of the remnant polarization in the PZT film affect the motion of hydrogen ions which determines the degradation of polarization characteristics and the shift in the P-E hysteresis curve of the PZT capacitor during hydrogen annealing. When the remnant polarization is formed in the PZT film by applying a pre-poling voltage prior to hydrogen annealing, the direction of the P-E curve shift induced by hydrogen annealing is opposite to the polarity of the pre-poling voltage. The hydrogen-induced degradation behavior of the PZT capacitor is also affected by the internal field that has been generated in the PZT film by the charges located at the top interface prior to hydrogen annealing.

The Structural and electrical Properties of $BaTiO_3$ Thin Films Deposited on Si/MgO Substrates (Si/MgO 기판에 증착된 BaTiO$_3$ 박막의 구조 및 전기적 특성)

  • 홍경진;김태성
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.11 no.12
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    • pp.1108-1114
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    • 1998
  • $BaTiO_3$ thin films preferred c-axis orientation for the potential application of ferroelectric memory devices were deposited on silicon substrates(100) by RF sputtering and annealed at 800 and 900[$^{\circ}C$] in air. The BT(100)/BT(110) peak ratio of the sputtered sample was decreased with post-annealing in air. According to increasing with annealing temperature and time, the peak ratio of BT(100)/BT(110) was decreased and the surface density of thin film was high. Dielectric characteristics of $BaTiO_3$ thin film was measured as a function of annealing temperature and frequency. The dielectric constants were increased with annealing and decreased with frequency by space charge polarization and dipole polarization below 600[kHz]. The remanent polarization and coercive field in P-E hysteresis loop of $BaTiO_3$thin film were increased with the annealing temperature in air. The remanent polarization and coercive filed annealed at 800[$^{\circ}C$] for 1hr were 1.2[$\mu$C/$cm^2$] and 200[kV/cm]

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Electrooptic Characteristics of PLZT Ceramics (PLZT 세라믹의 전기광학 특성)

  • 박창엽;박태곤;정익채
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.34 no.10
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    • pp.399-406
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    • 1985
  • In this paper transparent PLZT ceramics for the composition of 9/65/35 (La/Zr/Ti ) are fabricated using hotpress and the possibility of application to optical shutter is examined by obtaining the On-Off characteristics of specimens. The ferroelectric E-P hysteresis loop exhibits slim loop suitable for the quadratic electrooptic effect. Measurements of the electrooptic effect show that specimens have the quadratic electrooptic effect but the light intensities as functions of electric field exhibit butterfly type hysteresis curves because of its slightly large saturation remanent polarization and coercive field. On-Off characteristics are obtained by electric fields of-6 kv/cm and +2kv/cm. As a result of experiments, 9/65/35 PLZT ceramics can be applied to optical shutter but construction with other composition which has more slim hysteresis loop is desired for obtaining the Off state by zero electric field.

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