• Title/Summary/Keyword: Dielectric relaxation time

Search Result 86, Processing Time 0.027 seconds

Dielectric Relaxation Phenomena of Arac.acid (Arac.acid의 유전완화현상)

  • Song, Jin-Won;Cho, Su-Young;Lee, Young-Gil;Lee, Kyung-Sup
    • Proceedings of the KIEE Conference
    • /
    • 2003.07c
    • /
    • pp.1583-1585
    • /
    • 2003
  • Maxwell displacement current(MDC) measuring technique has been employed to study the dielectric property of Langmuir-films. A method for determining the dielectric relaxation time ${\tau}$ of floating monolayers on the water surface is presented. MDC flowing across monolayers is analyzed using a rod-like molecular model. It is revealed that the dielectric relaxation time ${\tau}$ of monolayers in the isotropic polar orientational phase is determined using a liner relationship between the monolayer compression speed ${\alpha}$ and the molecular area Am. Compression speed ${\alpha}$ was about 30, 40, 50mm/min.

  • PDF

High-precision THz Dielectric Spectroscopy of Tris-HCl Buffer

  • Lee, Soonsung;Kang, Hyeona;Do, Youngwoong;Lee, Gyuseok;Kim, Jinwoo;Han, Haewook
    • Journal of the Optical Society of Korea
    • /
    • v.20 no.3
    • /
    • pp.431-434
    • /
    • 2016
  • Tris-HCl buffer solution is extensively used in biochemistry and molecular biology to maintain a stable pH for biomolecules such as nucleic acids and proteins. Here we report on the high-precision THz dielectric spectroscopy of a 10 mM Tris-HCl buffer. Using a double Debye model, including conductivity of ionic species, we measured the complex dielectric functions of Tris-HCl buffer. The fast relaxation time of water molecules in Tris-HCl buffer is ~20% longer than that in pure water while the slow relaxation time changes little. This means that the reorientation dynamics of Tris-HCl buffer with such a low Tris concentration is quite different from that of pure water.

A study on the dielectric properties by measurement of relaxation time of dipole polarization in solid dielectrics (고체유전체의 쌍극자분극 완화시간 측정에 의한 유전특성의 연구)

  • 박중순;서장수;김병인;국상훈
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • 1992.05a
    • /
    • pp.125-129
    • /
    • 1992
  • When relaxation time will be distributed, TSC observed in the experimental procedure was analysed by using a potential model having two equilibrium positions and equations of dielectric properties was derived. Calculation of distribution was made by matrix method and compared/confirmed values obtained by TSC and alternating current which have a correspondence with each other. In this measurement, distribution of activation energy and relaxation time was determined by TSC peak at around 147k/364 of which center is 10$\^$-4/ sec/10$\^$5/ sec respectively at room temperature and also obtained dielctric loss factor at the range of 10$\^$-7/-10$\^$5/Hz. It seems that low temperature peak is local dispersion and high temperature peak have a relation to dielectric transition of the material.

  • PDF

Dielectric Properties of Oriental Lacquer Coating Network

  • 홍진후;김현경;허귀석;최종오
    • Bulletin of the Korean Chemical Society
    • /
    • v.18 no.7
    • /
    • pp.715-719
    • /
    • 1997
  • In order to study the dielectric properties of the oriental lacquer films, three different films have been prepared differing purification and curing procedures. Dielectric properties were measured in the frequency range of 1 Hz to 105 Hz at various temperatures between - 50 ℃ and 150 ℃. The DEA using 1 Hz showed that glass transition and secondary relaxation temperatures of oriental lacquer film are very time dependent. In addition, the frequency-independent negative peak between 25 ℃ and 45 ℃ was observed, which could represent the formation of crosslink by laccase enzyme during heating. On the contrary, the high temperature cured film showed a hardly noticeable negative peak at the temperature range. The relationship between thermodynamic properties and chemical structures has been discussed based on the analysis of the dielectric relaxation behavior using the Cole-Cole plot and the dielectric relaxation intensity.

A Study on the Electrical Physical Properties of Organic Thin Films for Manufacture in Power Device (전력용 소자 제작을 위한 유기박막 전기물성에 관한 연구)

  • Cho, Su-Young;Kim, Young-Keun;Choi, Young-Il;Song, Jin-Won;Lee, Kyung-Sup
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • 2004.05c
    • /
    • pp.37-41
    • /
    • 2004
  • In this paper, evaluation of physical properties about dielectric relaxation phenomena by the detection of the surface pressures and displacements current on the monolayer films of phospolipid monomolecular DLPC, DMPC using pressure stimulus. As a result, the changed surface pressure, displacement current and the transition forms of dipole moment of phospolipid monomolecular in area per molecular by pressure stimulus were conformed well. It was known that the monolayers by linear relationship for decision of dielectric relaxation time between compressure speed and molecule area By according to the linear relationship relation get that frictional constant, DLPC was $1.89{\times}10^{-19}$ [Js] and DMPC was $0.722{\times}10^{-19}$[Js]. lt is found that the phospolipid monolayer of dielectric relaxation takes a little time and depend on the molecular area.

  • PDF

Electrical and Dielectric Properties of ZPCCY-Based Varistor Ceramics with Sintering Time (ZPCCY계 바리스터 세라믹스의 소결시간에 따른 전기적, 유전적 특성)

  • 남춘우;김향숙
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
    • /
    • v.15 no.11
    • /
    • pp.946-952
    • /
    • 2002
  • The electrical and dielectric characteristics of ZPCCY-based varistor ceramics were investigated in the sintering time range of 1∼3 h. Increasing sintering time deteriorated the nonlinearity, in which nonlinear exponent is decreased from 51.2 to 23.8 and leakage current is increased from 1.3 to 5.6 $\mu$A. As sintering time increases, the donor concentration was decreased in the range of (1.25∼l.73)$\times$10$\^$18/cm$\^$-3/ and the density of interface states is (3.64∼94.19)$\times$10$\^$12/cm$\^$-2/ with increasing sintering time. The increase in sintering time caused tan $\delta$ to increase in the range of 0.043 to 0.062 and relaxation time to increase in the range of 1.55 to 2.23 ㎲.

Dielectric Characterization of Unsaturated Polyester Curing (불포화 폴리에스터의 경화에 따른 유전특성 연구)

  • 오경성;김홍경;김명덕;남재도
    • Polymer(Korea)
    • /
    • v.26 no.6
    • /
    • pp.728-736
    • /
    • 2002
  • The thermal and dielectric properties of unsaturated polyester resin system during cure were analyzed under Isothermal conditions. Both $varepsilon$′ and $varepsilon$" decreased and dipole relaxation was observed under isothermal conditions during cure. The ionic conductivity decreased linearly with the conversion according to the Kienle-Rate equation (ln($varepsilon$"$_{ionic}$we$_{0}$)=C$_{r}$$alpha$+C$_{0}$) up to $alpha$=0.15, after which it aparted from the relationship due to the entanglement of polymer chains. The effect of ionic conductivity was revealed to be larger than that of dipole motion during the whole cure through the electrical modulus analysis. Although dielectric motion was analyzed with Debye model, it was observed only at a narrow time region of middle stage of cure. In order to estimate the dielectric properties during the whole cure, the Havriliak-Negami model was considered and modified with the strong effect of ionic conductivity. The changes of $varepsilon$′ and $varepsilon$" were well estimated with this modified Havriliak-Negami model.

A Study on the Dielectric Properties of Phospholipid Organic Thin Films (인지질 유기박막의 유전특성에 관한 연구)

  • Song, Jin-Won;Lee, Kyung-Sup
    • Proceedings of the KIEE Conference
    • /
    • 1999.07d
    • /
    • pp.1983-1985
    • /
    • 1999
  • The dielectric constant of a monolayer on a material surface was calculated with consideration of the local field acting on polar molecules with a permanent dipole moment, and the interaction working between the molecules and a material. It is revealed that the dielectric relaxation time r of monolayers in the isotropic polar orientational phase is determined using a linear relationship between the monolayers compression speed a and the molecular area. The dielectric relaxation time of phospholipid monolayers was examined on the basis of analysis developed here.

  • PDF

A Study on the Preparation and Dielectric Characteristic of $\beta$-PVDF Vapor Deposited Thin Films by Applied Electric Field Method (전계인가법을 이용한 $\beta$-PVDF 증착 박막의 제조와 유전특성에 관한 연구)

  • 박수홍;이덕출
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
    • /
    • v.11 no.3
    • /
    • pp.221-228
    • /
    • 1998
  • In this study, the $\beta$-Polyvinylidene fluoride(PVDF) thin films were fabricated by physical vapor deposition method. Also, the properties of dielectric relaxation were studied to understand carrier's behavior of PVDF thin films, to be regarded as the excellent piezo and pyroelectricity. In the process of vapor deposition, the $\beta$-PVDF thin films have been fabricated under the condition of the substrate temperature at 3$0^{\circ}C$, the applied electric field at 142.8kV/cm and the pressure at 2.0${\times}10^{-5}$torr. The dielectric properties of PVDF have been studied in the frequency range 10Hz to 1MHz at temperature from 30 to $100^{\circ}C$. The relative dielectric constant of $\alpha$ and $\beta$-PVDF were 6.8 and 9.8, respectively, under a frequency of 1kHz. Such a phenomenon was caused by the decrease in intermolecular forces originated by the phase-transition from the TGTG' molecular conformation to the TT planar zig-zag conformation. And the relative dielectric constant is increased as a measuring temperature increases, because of the reduction of relaxation time caused by the decrease of intermolecular force.

  • PDF

Dielectric Changes During the Curing of Epoxy Resin Based on the Diglcidyl Ether of Bisphenol A (DGEBA) with Diamine

  • 김홍경;차국헌
    • Bulletin of the Korean Chemical Society
    • /
    • v.20 no.11
    • /
    • pp.1329-1334
    • /
    • 1999
  • The curing characteristics of diglycidyl ether of bisphenol A (DGEBA) with diaminodiphenylmethane (DDM) as a curing agent were studied using differential scanning calorimetry (DSC), rheometrics mechanical spectrometry (RMS), and dielectric analysis (DEA). The isothermal curing kinetics measured by DSC were well represented with the generalized auto-catalytic reaction model. With the temperature sweep, the inverse relationship between complex viscosity measured by RMS and ionic conductivity obtained from DEA was established indicating that the mobility of free ions represented by the ionic conductivity in DEA measurement and the chain segment motion as revealed by the complex viscosity measured from RMS are equivalent. From isothermal curing measurements at several different temperatures, the ionic conductivity contribution was shown to be dominant in the dielectric loss factor at the early stage of cure. The contribution of the dipole relaxation in dielectric loss factor became larger as the curing further proceeded. The critical degrees of cure, at which the dipolar contribution in the dielectric loss factor starts to appear, increases as isothermal curing temperature is increased. The dielectric relaxation time at the same degree of cure was shorter for a sample cured at higher curing temperature.