• 제목/요약/키워드: Electrical conductivity and resistivity

검색결과 313건 처리시간 0.026초

Y-type hexagonal Ferrite의 전기적 특성 (Electrical Properties of Y-type Hexagonal Ferrite)

  • 박영민;최경만
    • 한국세라믹학회지
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    • 제30권11호
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    • pp.962-966
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    • 1993
  • Effect of Fe content on the electrical properties of Zn2Y (Ba2Zn2Fe12O22) was studied by investigating X-ray diffraction patterns, microstructure and resistivity of samples. When x(Ba2Zn2Fe12+xO$\delta$) is between +1 and -1, Zn2Y single phase was obtained and electrical resistivity was inversely proportional to Fe content. The possible defect model of Zn2Y was proposed based on the observation. When x<-1 or x>1, second phase(ZnFe2O4 for x<-1, ZnFe2O4 and Ba3Zn3Fe24O41 for x>1) were observed and the electrical resistivity was inversely proportional to the sample density. The activation energy of electrical conductivity of the stoichiometric Zn2Y was 0.49eV below 20$0^{\circ}C$ and 0.07eV above 50$0^{\circ}C$.

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시추공 전기비저항 토모그래피를 이용한 비저항 영상화: 과잉취수에 의한 석회암 지반침하 지역 사례 (Resistivity Imaging Using Borehole Electrical Resistivity Tomography: A Case of Land Subsidence in Karst Area Due to the Excessive Groundwater Withdrawal)

  • 송성호;이규상;엄재연;서정진
    • 한국지구과학회지
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    • 제32권6호
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    • pp.537-547
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    • 2011
  • 석회암 공동이 발달한 도심지역에서 지하수위 하강에 수반되어 발생한 함몰형 지반침하의 원인 규명 및 공동의 분포 특성 파악을 위하여 시추공을 이용한 전기비저항 토모그래피탐사를 실시하였다. 이때 지하수 수리지질 특성을 파악하기 위하여 시추코아의 비저항 측정, 지하수위 측정 및 수리전도도 해석을 병행하였다. 연구 지역에서의 완만한 지하수위 분포 특성과 0.8-$9.3{\times}10^{-4}\;cm/s$ 범위의 수리전도도 분포로 부터 연구지역의 수리지질 특성은 불균질성이 크지 않은 것으로 나타났다. 시추코아를 이용한 전기비저항 측정 결과 연구지역의 석회암은 파쇄가 많은 경우, 변질이 심한 경우 및 신선한 경우로 나눠지며, 전기비저항은 각각 103-161, 218-277 및 597-662 ohm-m의 범위로 나타났다. 시추결과 점토로 충전된 석회암 공동 지점은 토모그래피 탐사자료의 역산 결과 50 ohm-m 이하의 낮은 비저항으로 나타났으며, 각 시추공 간 비저항 영상 단면으로부터 연구지역 전체적으로 지표 하부 심도 약 10-20 m 구간까지 파쇄대 또는 석회암 공동 구간이 분포하는 것으로 나타났다. 또한 석회암 공동의 직경은 약 4-6 m 규모로, 대부분 점토질로 충전된 것으로 판단된다.

Optical and Electrical Properties of Indium Doped PEDOT:PSS

  • Kim, Byoung-Ju;Kang, Kwang-Sun
    • Current Photovoltaic Research
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    • 제5권4호
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    • pp.109-112
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    • 2017
  • Various wt. ratios of indium were doped to the poly(3,4-ethylenedioxythiophene)-poly(styreneswulfonate) (PEDOT:PSS) to enhance the conductivity and transmittance. The transmittance of the films increased with increasing the amount of indium. The field emission scanning electron microscope (FESEM) image of 2.54 wt. % of indium doped PEDOT:PSS film shows large number of aggregated indium particles. However, more than 2.54 wt. % of indium doped PEDOT:PSS films showed reduced aggregated indium particles. Moreover, 4.47 wt. % of indium doped PEDOT:PSS film showed no aggregated particles. The resistivity of pure PEDOT:PSS film showed $880k{\Omega}{\cdot}cm$. The resistivity of 1.03 wt. % indium doped film reduced approximately 26 times compared with pure PEDOT:PSS film. The resistivity of indium doped film further reduced with increasing the amount of indium, which showed approximately $0.55k{\Omega}{\cdot}cm$ for the PEDOT:PSS film doped 4.47 wt. % of indium.

Experimental evaluation of electrical conductivity of carbon fiber reinforced fly-ash based geopolymer

  • Vaidya, Saiprasad;Allouche, Erez N.
    • Smart Structures and Systems
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    • 제7권1호
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    • pp.27-40
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    • 2011
  • Geopolymer concrete is finding a growing number of niche applications in the field of civil engineering due to its high compressive strength and strength gain rate, retainage of structural properties in elevated temperature environments, chemical stability in highly acidic conditions and environmental benefits. Combining the above mentioned characteristics with induced electrical conductivity, could enable geopolymer cement to serve as a smart and sustainable cementitious material suitable for health monitoring of civil structures. Carbon fibers were added to fresh geopolymer and OPC (ordinary Portland cement) mixes to enhance their electrical conductivities. AC-impedance spectroscopy analysis was performed on the specimens with fiber fraction ranging from 0.008 to 0.8 with respect to the weight of cementitious binder, to measure their electrical resistivity values and to determine the maximum beneficial fiber content required to attain electrical percolation. Experimental observations suggest that CFR-geopolymer cement exhibits superior performance to CFR-OPC in terms of conducting electrical current.

P형 열전분말의 수소환원처리가 상온열전특성에 미치는 영향 (Effect of Hydrogen Reduction Treatment on Room-Temperature Thermoelectric Performance of p-type Thermoelectric Powders)

  • 김경태;장경미;하국현
    • 한국분말재료학회지
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    • 제17권2호
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    • pp.136-141
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    • 2010
  • Bismuth-telluride based $(Bi_{0.2}Sb_{0.8})_2Te_3$ thermoelectric powders were fabricated by two-step planetary milling process which produces bimodal size distribution ranging $400\;nm\;{\sim}\;2\;{\mu}m$. The powders were reduced in hydrogen atmosphere to minimize oxygen contents which cause degradation of thermoelectric performance by decreasing electrical conductivity. Oxygen contents were decreased from 0.48% to 0.25% by the reduction process. In this study, both the as-synthesized and the reduced powders were consolidated by the spark plasma sintering process at $350^{\circ}C$ for 10 min at the heating rate of $100^{\circ}C/min$ and then their thermoelectric properties were investigated. The sintered samples using the reduced p-type thermoelectric powders show 15% lower specific electrical resistivity ($0.8\;m{\Omega}{\cdot}cm$) than those of the as-synthesized powders while Seebeck coefficient and thermal conductivity do not change a lot. The results confirmed that ZT value of thermoelectric performance at room temperature was improved by 15% due to high electric conductivity caused by the controlled oxygen contents present at bismuth telluride materials.

Investigations of Temperature Effect on the Conduction Mechanism of Electrical Conductivity of Copolymer/Carbon Black Composite

  • El Hasnaoui, M.;Kreit, L.;Costa, L.C.;Achour, M.E.
    • Applied Microscopy
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    • 제47권3호
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    • pp.121-125
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    • 2017
  • This study deals the prediction of temperature effect on low-frequency dispersion of alternating current (AC) conductivity spectra of composite materials based on copolymer reinforced with carbon black (CB) particles. A sample of ethylene butylacrylate loaded with 13% of CB particles were prepared and investigated using the impedance spectroscopy representation in the frequency range from 40 Hz to 0.1 MHz and temperature range from $20^{\circ}C$ to $125^{\circ}C$. The dielectric constant, ${\varepsilon}^{\prime}$, and dielectric losses, ${\varepsilon}^{{\prime}{\prime}}$, were found to decrease with increasing frequency. The frequency dependence of the AC conductivity follows the universal power law with a large deviation in the high frequency region, the positive temperature coefficient in resistivity effect has been observed below the melting temperature which makes this composite potentially remarkable for industrial applications.

태양전지 CIGS용 Mo 후면전극의 전기 저항에 관한 연구 (The Study on the Electrical Resistivity for Mo Back Contacts Film of CIGS Solar Cell)

  • 김강삼;조용기
    • 한국표면공학회지
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    • 제44권6호
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    • pp.264-268
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    • 2011
  • The Molybedenium thin film is generally used on back contact material of CIGS solar cell due to low electrical resistivity and stable thermal expansion coefficient. The Mo thin films deposited on si wafer by the magnetron sputtering method. The research focused on the variation of electrical resistivity of films which deposited with various working pressure at the target power of 2.0 kW(8.4 W/). The lowest resistivity of Mo thin film showed $9.0{\mu}O$-cm at pressure of 1.5 mTorr. However, working pressure increasing up to 50 mTorr, resistivities were highly increased. The results showed that the conductivity of Mo films depended on growing structures and defects in deposition process. Surface morphology, porosity, grain size, oxidation, and bonding structures were analysed by SEM, AFM, spectroscopic ellipsometry (SE), XRD, and XPS.

에코콘 관입시스템을 이용한 지반의 현장원위치 수리전도도 측정

  • 정하익;김상근;송봉준;강동우;이경국
    • 한국지하수토양환경학회:학술대회논문집
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    • 한국지하수토양환경학회 2004년도 임시총회 및 추계학술발표회
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    • pp.262-265
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    • 2004
  • The purpose of this study is to investigate environmental characteristics and in-situ hydraulic conductivity by eco cone penetration system. The underground environments and permeability of site was investigated and analyzed by this eco cone system. The electrical resistivity, pH, ORP, temperature and hydraulic conductivity were measured by eco cone penetration system. This eco cone penetration system provides a continuous environment and permeability profiles in underground, and provides reliable results for investigation of normal and contaminated ground.

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The Electrical Property of Polymer Matrix Composites Added Carbon Powder

  • Shin, Soon-Gi
    • 한국재료학회지
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    • 제25권12호
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    • pp.678-682
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    • 2015
  • The electrical property of polymer matrix composites with added carbon powder is studied based on the temperature dependency of the conduction mechanism. The temperature coefficient of the resistance of the polymer matrix composites below the percolation threshold (x) changed from negative to positive at 0.20 < x < 0.21; this trend decreased with increasing of the percolation threshold. The temperature dependence of the electrical property(resistivity) of the polymer matrix composites below the percolation threshold can be explained by using a tunneling conduction model that incorporates the effect of the thermal expansion of the polymer matrix composites into the tunneling gap. The temperature coefficient of the resistance of the polymer matrix composites above the percolation threshold has a positive value; its absolute value increased with increasing volume fraction of carbon powder. By assuming that the electrical conduction through the percolating paths is a thermally activated process and by incorporating the effect of thermal expansion into the volume fraction of the carbon power, the temperature dependency of the resistivity above the percolation threshold can be well explained without violating the universal law of conductivity.

플라즈마 강화 원자층 증착법에 의한 TaNx 박막의 전기 전도도 조절 (Electrical Conductivity Modulation in TaNx Films Grown by Plasma Enhanced Atomic Layer Deposition)

  • 류성연;최병준
    • 한국재료학회지
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    • 제28권4호
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    • pp.241-246
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    • 2018
  • $TaN_x$ film is grown by plasma enhanced atomic layer deposition (PEALD) using t-butylimido tris(dimethylamido) tantalum as a metalorganic source with various reactive gas species, such as $N_2+H_2$ mixed gas, $NH_3$, and $H_2$. Although the pulse sequence and duration are the same, aspects of the film growth rate, microstructure, crystallinity, and electrical resistivity are quite different according to the reactive gas. Crystallized and relatively conductive film with a higher growth rate is acquired using $NH_3$ as a reactive gas while amorphous and resistive film with a lower growth rate is achieved using $N_2+H_2$ mixed gas. To examine the relationship between the chemical properties and resistivity of the film, X-ray photoelectron spectroscopy (XPS) is conducted on the ALD-grown $TaN_x$ film with $N_2+H_2$ mixed gas, $NH_3$, and $H_2$. For a comparison, reactive sputter-grown $TaN_x$ film with $N_2$ is also studied. The results reveal that ALD-grown $TaN_x$ films with $NH_3$ and $H_2$ include a metallic Ta-N bond, which results in the film's higher conductivity. Meanwhile, ALD-grown $TaN_x$ film with a $N_2+H_2$ mixed gas or sputtergrown $TaN_x$ film with $N_2$ gas mainly contains a semiconducting $Ta_3N_5$ bond. Such a different portion of Ta-N and $Ta_3N_5$ bond determins the resistivity of the film. Reaction mechanisms are considered by means of the chemistry of the Ta precursor and reactive gas species.