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dielectric Behavior of Middle Phase Microemulsion

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Chinese Chemical Letters 2000年第8期11卷 739-742页

作者： Lei, JP Li, Y Zhao, KS S China Normal Univ Dept Chem Guangzhou 510631 Peoples R China

dielectric measurements were performed on middle phase microemulsions composed of sodium dodecylsulfate(SDS), cetyltrimethylammonium bromide(CTAB), n-butanol, n-heptane and brine. Distinct and unique dielectric behavior, with characteristic frequency dependence regularity on the salinity of the microemulsions, was observed in the low-frequency range from 10-10(3)Hz. It can be considered to be an interfacial polarization mechanism.

关键词： middle phase microemulsions dielectric spectroscopy relaxation time

dielectric and ferroelectric properties of CoCr_(2)O_(4)nanoceramics

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Journal of Advanced dielectrics 2019年第3期9卷 1-7页

作者： Pankaj Choudhar P.Saxena A.Yadav V.N.Rai A.Mishra Materials Science Laboratory School of Physics Vigyan BhawanDevi Ahilya University Khandwa Road CampusIndore 452001India Department of Physics Medi-Caps University PigdamberIndore 453331India

CoCr_(2)O_(4)nanoceramics are prepared by sol-gel auto combustion *** X-ray diffraction analysis affirms the singlephasepristine cubic structure with space group ***-Scherrer method estimates the crystallite size of main intense peak tobe~27:15 *** bands obtained in infrared spectra at 448 and 599 cm^(-1)are due to metal-oxygen stretching bond presentat tetrahedral and octahedral *** parameters decrease as frequency increases from 103 to 106 Hz that can be interpretedby Maxwell-Wagner-type interfacial *** impedance spectra(Nyquist plot)reveal arc like behavior,which ismainly due to intergrain(grain boundary)resistance that also exhibits conducting nature of the *** ferroelectricityis mainly associated with the partial reversal of the *** current behavior follows the Ohmic and Child square *** conduction process was interpreted by space-charge limited current(SCLC)*** current behaviorobserved in cobalt chromite nanoceramics is mainly attributed to the oxygen vacancies.

关键词： CoCr_(2)O_(4)nanoceramics synchrotron X-ray diffraction dielectric spectroscopy electric polarization leakage currentbehavior

Change in dielectric relaxation with the presence of water in highly filled composites

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Journal of Advanced dielectrics 2017年第5期7卷 36-46页

作者： Enis Tuncer Texas Instruments Incorporated Dallas Texas 75243USA

It is important to determine the dielectric characteristics of semiconductor encapsulation materials based on epoxy *** employed the dielectric spectroscopy technique to investigate the dielectric relaxation in the presence of water and how it changes the *** was observed that the dielectric relaxation of the material was significantly influenced by absorbed water,the local segmental motion(also known as Johari-Goldstein(β)relaxation)was influenced most by the presence of the water,it was modified by the wet sample compared to dry one,and required high activation *** relaxation related to the glass transition was contributed by the cooperative motion(the a-relaxation)of the epoxy resin *** a-relaxation was shifted to a low temperature in the wet sample compared to dry *** relaxation was modeled with a clear Vogel-Fulcher-Tammann-Hesse(VFTH)behavior;the Vogel temperature of the wet sample was 8 K lower than the dry *** presence of water acts as a plasticizer for the molecular relaxation,and speed-up the cooperative *** measured data were also used to estimate the electrical properties of the resin system by employing an effective-medium model together with a porous media continuum model by taking into account the physical properties of the *** is already known that the influence of water in semiconductor packaging is important in sensitive *** presented measurements and the analysis method would be appreciated within the semiconductor packaging community to improve material selection and performance evaluation efforts.

关键词： Composite materials semiconductor packaging dielectric spectroscopy

Investigation of structural phase evolution and dielectric response of Co-doped BaTiO_(3)

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Journal of Advanced dielectrics 2018年第4期8卷 14-19页

作者： Amantulla Mansuri Ilyas Noor Bhatti Imtiaz Noor Bhatti Ashutosh Mishra School of Physics Devi Ahilya University Indore 452001India Department of Physics Jamia Millia Islamia New Delhi 110025India School of Physical Sciences Jawaharlal Nehru University New Delhi 110067India

In the present study,we have synthesized polycrystalline samples of BaTi_(1-x)Co_(x)O_(3)(BTCO)(x=0,0.01,0.03,0.05,0.07 and 0.10)with standard solid state reaction *** obtained samples are characterized by X-ray diffraction(XRD)and Raman spectroscopy for structural *** detailed structural analysis has been performed by Rietveld refinement using Fullprof *** observed an increase in lattice parameters,which results due to substitution of Co2t with large ionic radii(0.9Å)for smaller ionic radii(0.6Å)***,peak at 45.5°shifts to 45°on Co doping,which is due to structure phase transition from tetragonal to *** study infers that the intensity of characteristic peaks decreases and line width increases with Co *** bands linked with the tetragonal structure(305 cm1)decreased due to the tetragonal-to-cubic phase transition with Co *** structural study reveals the expansion of BTCO unit cell and tetragonal-to-cubic phase transformation takes *** results from different characterization techniques are conclusive and show structural evolution with Co *** samples are further characterized by dielectric spectroscopy,dielectric measurement reveals the increase of dielectric constant and transition T_(c)-125° is observed for Barium titanate(BaTiO3),whereas transition disappears with Co *** temperature and frequency-dependent tangent loss is also studied.

关键词： Oxides dielectric spectroscopy Raman spectroscopy structural characterization.

Stable dielectric response of low-loss aromatic polythiourea thin films on Pt/SiO_(2) substrate

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Journal of Advanced dielectrics 2016年第1期6卷 46-49页

作者： A.Eršte L.Fulanović L.Čoga M.Lin Y.Thakur Q.M.Zhang V.Bobnar Jožef Stefan Institute Jamova cesta 39 SI-1000 LjubljanaSlovenia Faculty of Mathematics and Physics University of Ljubljana Jadranska ulica 19SI-1000 LjubljanaSlovenia Department of Electrical Engineering and Materials Research Institute The Pennsylvania State University University ParkPennsylvania 16802USA

We have investigated dielectric properties of aromatic polythiourea(ArPTU,a polar polymer containing high dipolar moments with very low defect levels)thin films that were developed on Pt/SiO_(2) *** detected response is compared to the response of commercially available polymers,such as high density polyethylene(HDPE)and polypropylene(PP),which are at present used in foil *** values of the dielectric constantε'≈5(being twice higher than in HDPE and PP)over broad temperature and frequency ranges and dielectric losses as low as in commercial systems suggest ArPTU as a promising candidate for future use in a variety of applications.

关键词： Aromatic polythiourea dielectric polymer film capacitor dielectric spectroscopy ellipsometry

CH ARACTERIZATION OF LA YERED Na_(2-x-y)LixKyTi_(3)O_(7) CERAMICS BY dielectric-SPECTROSCOPIC INV ESTIG ATIONS

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Journal of Advanced dielectrics 2011年第4期1卷 429-437页

作者： SHRIPAL RAKESH SINGH GEETIKA RAVI K.SHUKLA K.K.RAINA Department of Physics P.P.N.College Kanpur 208001India School of Physics&Materials Science Thapar University Patiala 147004India

In this paper,we present detailed investigations on the dielectric properties of Lithium(x=0.10)and Potassium(y=0.01,0.02,0.04,0.05)mixed Sodium trititanate,Na_(2-x-y)LixKyTi_(3)O_(7) poly-crystalline ma terials synthesized by solid-state *** characteristics of the pelletized samples have been studied in the temperature range from 350 to 725 K and on the frequency in the range from 10kHz to 1 *** studies reveal that the chain structured Na_(2-x-y)LixKyTi_(3)O_(7) layered compound posses electronic,ionic,dipolar,and space charge polarization mechanisms over the respective temperature regions in the entire temperature range of study.

关键词： Layered titanates dielectric spectroscopy dielectric loss permittivity polarization

dielectric RELAXATION IN RELAXOR FERROELECTRICS

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Journal of Advanced dielectrics 2012年第2期2卷 10-33页

作者： ALEXEI A.BOKOV ZUO-GUANG YE Department of Chemistry and 4D LABS Simon Fraser University 8888 University Drive BurnabyBritish ColumbiaV5A 1S6Canada Electronic Materials Research Lab.Key Lab.of the Ministry of Education and International Center for dielectric Research Xi'an Jiaotong University Xi'an 710049P.R.China

In this review the dielectric properties of relaxor ferroelectrics are discussed and compared withthe properties of normal dielectrics and ferroelectrics. We try to draw a general picture ofdielectric relaxation starting from a textbook review of the underlying concepts and pay attentionto common behavior of relaxors rather than to the features observed in specific materials. We hopethat this general approach is beneficial to those physicists, chemists, material scientists and deviceengineers who deal with relaxors. Based on the analysis of dielectric properties, a comprehensivedefinition of relaxors is proposed: relaxors are defined as ferroelectrics in which the maximum inthe temperature dependence of static susceptibility occurs within the temperature range ofdielectric relaxation, but does not coincide with the temperature of singularity of relaxation timeor soft mode frequency.

关键词： Relaxor ferroelectrics dielectric spectroscopy stretched exponential relaxation Vogel-Fulcher law

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复介电系数谱的测量

微波 1986年第3期 44-53页

作者：倪尔瑚浙江大学

本文对电介质波谱技术进行极扼要的综述。提出介电谱技术的分类方法,简述复介电系数频率谱(?)(ω)测量方法的基本概念和原理,实验方法和技术目前状态的轮廊,并指出各类方法的优缺点和适用范围。

关键词： dielectric spectroscopy dielectric measurēment Microwave measurement