• Title/Summary/Keyword: dielectric polarization

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Recent Progress in Dielectric-Based Ultrafast Charging/Discharging Devices (유전체를 활용한 초고속 에너지 충/방전 소자 기술)

  • Choi, Hyunsu;Ryu, Jungho;Yoon, Woon-Ha;Hwang, Geon-Tae
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.35 no.4
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    • pp.322-332
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    • 2022
  • Energy storage capacitors based on dielectric ceramics with superior polarization properties and dielectric constant can provide much higher output power density due to their very fast energy charging/discharging rates, which are particularly suitable for operating pulsed-power devices. For an outstanding energy storage performance of dielectric capacitor, a large recoverable energy density could be derived by introducing a slim polarization-electric field hysteresis loop into dielectric materials by various technical approaches. Many research teams have explored various dielectric capacitor technologies to demonstrate high output power density and ultrafast charging/discharging behavior. This article reviews the recent research progress in high-performance dielectric capacitors for pulsed-power electronic applications.

Electrode Polarization and Interfacial Polarization in Composite of Ion conductive Polymer and PZT particles (이온전도성 고분자와 PZT미립자의 복합체에 있어서 전극분극과 계면분극 현상)

  • Park, Sang-Ho;Kang, Dae-Ha
    • Proceedings of the KIEE Conference
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    • 2005.07c
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    • pp.1838-1840
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    • 2005
  • Dielectric and conductive spect frequency spectra in a $1Hz{\sim}13MHz$ range have been measured for the composite consisting of PZT inclusions dispersed in a $LiClO_4$ doped polyethylene oxide(Li_PEO) matrix with various volume fractions. The dielectric and conductive spectra of the composites revealed the relaxations related with electrode polarization and interfacial polarization The observed spectra were reproduced using the empirical function and we could obtain vairous parameters related to electrode polarization and interfacial polarization.

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Microstructure and Pyrochlore Phase Dependence on the Dielectric Properties of Lead Magnesium Niobate Ceramics (Lead Magnessium Niobate 세라믹의 유전성에 대한 미세구조와 Pyrochlore상 의존성)

  • 강동현;윤기현
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1989.06a
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    • pp.105-106
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    • 1989
  • The effects of pyrochlore phase and micostructure on the dielectric properties. such as dielectric constant, dissipation factor, diffusensess coefficient and dielectric hysteresis characteristics, of Lead magnesium niobate(PMN) ceramics have been studied as a function of the amount of excess MgO. The pyrochlore phase in PMN was completely eliminated with the addition of 5 m/o excess MgO. Also, the dielectric constant and remanent polarization increased with increase in grain size, density and then decreased with grain growth inhibitation for further addition of excess MgO. The diffuseness coefficient showed a tendency nearly reverse to that for the dielectric constant and remanent polarization change.

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Dielectric Properties depending on Bias Voltage in Organic Light-emitting Diodes (유기 발광 소자의 바이어스 전압에 따른 유전 특성)

  • Oh, Yong-Cheul;Lee, Joon-Ung
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.18 no.11
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    • pp.1038-1042
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    • 2005
  • We have investigated dielectric properties depending on bias voltage in organic light-emitting diodes using 8-hydroxyquinoline aluminum $(Alq_3)$ as an electron transport and emissive material. We analyzed the dielectric properties of organic light-emitting diodes using impedance of characteristics. Impedance characteristics was measured complex impedance Z and phase $\theta$ in the frequency range of 40 Hz to $10^8$ Hz. We obtained complex electrical conductivity, dielectric constant, and loss tangent $(tan\delta)$ of the device at room temperature. From these analyses, we are able to interpret a conduction mechanism and dielectric properties contributed by an interfacial and orientational polarization.

A study on the dielectric dispersion of vulcanized natural rubber (가황에 의한 천연고무의 유전분산에 관한연구)

  • Lee, Joon-Ung;Kim, Hak-Ju
    • Elastomers and Composites
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    • v.18 no.2
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    • pp.51-59
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    • 1983
  • The dielectric properties of polymers are very important when investigating the molecular structure of polymers. The characteristics of the dielectric absorption in vulcanized natural rubber were studied in frequency ranging from 10[KHz] to 32[MHz] at the temperature of 25[$^{\circ}C$]. As a result of the study, it has been confirmed that natural rubber vulcanized below 4phr leads to two kinds of dielectric losses due to the interfacial polarization and the dipole polarization by sulfur, and of above 7[%] was only a loss due to the dipole polarization by sulfur. Futhermore, the dielectric loss maximum $tan{\delta}$ spectrum, removed to the low frequency in accordance with increasing sulfur, depends greatly on sulfur. The volume resistivity of $10^{7}{\sim}10^{11}[{\Omega}{\cdot}cm}]$, regardless of whether the crosslinking of rubber is weakened by sulfur, was observed.

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Complex Dielectric Constant of Soil Contaminated by Landfill Leachate with Measured Frequency (매립지 침출수로 오염된 토양의 측정주파수에 따른 유전특성 변화)

  • Oh Myoung-Hak;Bang Sun-Young;Park Jun-Boum;Lee Ju-Hyung;Lee Seock-Heon;Ahn Kyu-Hong
    • Journal of Soil and Groundwater Environment
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    • v.9 no.3
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    • pp.1-11
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    • 2004
  • To evaluate the applicability of dielectric constant measurement method on the geoenvironmental investigation of subsurface contaminated by landfill leachate, the analysis on dielectric characteristics of sand containing contaminated pore water by landfill leachate was performed. The separate real and imaginary parts of dielectric constant were investigated in the frequency range of 75kHz to 12MHz. The real part of dielectric constant increased at the lower frequency wherea the real part of dielectric constant decreased at the higher frequency as the concentration of leachate increased. These results can be explained by the frequency dependence of space charge polarization and orientation polarization. The imaginary part of dielectric constant on the contaminated sand with leachate increased with their concentration for whole frequency range. These results are caused by the increase of energy loss due to the enhancement of conduction in soil with leachate concentration. The results in this study indicate that the dielectric constant measurement method has potential in evaluating the contaminated soil and pore water by landfill leachate.

The Dielectric Properties of BaTi $O_3$ by Additive Material (첨가제에 의한 BaTi $O_3$의 유전특성)

  • 홍경진;정우성;민용기;김태성
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1996.11a
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    • pp.413-416
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    • 1996
  • The ceramic dielectrics were fabricated by mixing of Mn $O_2$ and ZnO at (B $a_{0.85}$ $Ca_{0.15}$)Ti $O_3$ and studied for dielectric relaxation characteristics. The dielectric relaxation time was increased by space charge polarization of palaelectric layer at the low temperature and frequency but it was decreased by Interface polarization at the high temperature and frequency. The remnant polarization and coercive field of ceramic dielectrics was decreased by rising temperature.ure.

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The Electrorheological and Dielectric Behaviors of Conducting Polymer-coated Poly(ethyl methacrylate) Suspensions

  • Kim, Young-Dae;Park, Dong-Hyup;Nam, Suk-Woo;Park, Tae-Jin
    • Macromolecular Research
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    • v.10 no.4
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    • pp.215-220
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    • 2002
  • The electrorheological (ER) and dielectric behaviors of the polypyrrole(PPy)-coated poly(ethyl methacrylate)(PEMA) suspensions in mineral oil were investigated. PPy was coated on PEMA particles to enhance the particle polarization, which would lead to the enhanced ER response. Various PPy-coated PEMA particles were synthesized by controlling the oxidant amount during the pyrrole polymerization, and the ER responses of their suspensions were investigated. The ER response initially increases with the oxidant amount, passes through a maximum, and then decreases with the oxidant amount. The initial increase in the ER response with oxidant amounts is due to the enhanced particle polarization with the increased particle surface conductivity. The dielectric properties of the corresponding suspensions support that the ER enhancement arises from the enhanced particle polarization. The decrease in the ER response at large oxidant amounts seems to arise from the increased conduction between the PPy-coated PEMA particles.

Properties of Electric Sofety for Dielectric Loss of Aging Natural Rubber. (노화된 천연고무의 유전손실에 관한 전기안전특성)

  • 이성일;권호영
    • Journal of the Korean Society of Safety
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    • v.6 no.4
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    • pp.5-12
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    • 1991
  • The dielectric properties of natural rubbers for electric safety are very important to investigate the molecular structure. The electric safety characteristics of the dielectric absorption in aging vulcanized natural rubber were studied in the range of frequency from 1$\times$10$^3$[Hz]to 3.2$\times$10$^3$[Hz]l at the temperature of 23[$^{\circ}C$]. As the results, it has been confirmed that in the case of aging natural rubber of above 2 phr the specimens exhibit two kinds of dielectric losses due to the dipole polarization by impurities and sulfurs, and of raw rubber exhibit the kind of losses due to the dipole polarization. Rurthermore, dielectric loss maximum tansspectrum in high freguency region for electric safety, which removed to the low freguency according to increasing sulfur, depends greatly on sulfur.

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Dielectric properties of Eu-doped PZT thin films (Eu 첨가에 따른 PZT 박막의 유전 특성)

  • Son, Young-Hoon;Kim, Kyeong-Tae;Kim, Chang-Il;Chang, Eui-Goo;Lee, Byoung-Ki
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2002.11a
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    • pp.155-158
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    • 2002
  • Eu-doped lead zirconium titanate $Pb_{1.1}(Zr_{0.3}Ti_{0.7})O_{3}$ thin films on the Pt/Ti/$SiO_2$/Si substrates prepared by a metalorganic decomposition (MOD) method. The effect on the structural and electrical properties of the films measured according to Eu content. Eu-doping altered significantly the dielectric and ferroelectric properties. The remanent polarization and coercive field decreased with increasing the concentration of Eu content. The dielectric constant and dielectric loss of the film decreased with increasing Eu contents. The 3 mol% of Eu-doped PZT thin film showed large remanent polarization and the fatigue characteristic of the film did not change up to $10^9$ switching cycles.

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