AC Impedance (ac + impedance)

Distribution by Scientific Domains
Polymers and Materials Science50%
Chemistry50%

Terms modified by AC Impedance

  • ac impedance measurement
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  • ac impedance spectroscopy
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    Selected Abstracts

    Corrosion control of phenylthiourea polymers on aluminium in alkaline medium

    MATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 1 2008
    B. J. Vasanthi
    Simple phenylthiourea compounds are known for their high solubility in alkaline medium and for good corrosion control. The monomer N -(4-hydroxy-3-methoxybenzal)- N,-(4,-hydroxyphenyl) thiourea was condensed with pimeloylchloride and azeloylchloride through inter-facial polycondensation method to synthesize the polymers. The polymers were dissolved in 2 N sodium hydroxide and their corrosion controlling efficiency on aluminium was studied through AC impedance and potentiodynamic polarization methods. [source]

    Synergistic or additive corrosion inhibition of mild steel by a mixture of HEDP and metasilicate at pH 7 and 11

    MATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 11 2004
    D. Mohammedi
    Abstract Electrochemical measurements (steady-state current-voltage curves and AC impedance) were coupled with mass-loss measurements, SEM examinations, and EDSX analyses to investigate the inhibition of corrosion of a carbon steel by a mixture of phosphonic acid HEDP (acid 1, hydroxyethylene, 1-1 diphosphonic) and sodium metasilicate pentahydrate Na2SiO3. 5H2O in an industrial hard water containing 3.10,3 M Ca2+ ions. At pH 7, HEDP and Ca2+ act in a synergistic manner, by formation of a HEDP and calcium containing layer. Addition of silicate at this pH value, allows to reach an efficiency of 94% due to an additive inhibition effect. At pH 11, metasilicate, HEDP, and Ca2+ ions reinforce the passive layer in a synergistic way. The mixture (1.7 · 10,5 M HEDP + 2.6 · 10 -3 M SiO2,3) in the Ca2+ containing electrolyte is shown to be able to inhibit efficaciously the corrosion of iron at room temperature, considering uniform corrosion at pH 7 or pitting corrosion at pH 11. [source]

    AC impedance analysis and EMI shielding effectiveness of conductive SBR composites

    POLYMER ENGINEERING & SCIENCE, Issue 10 2006
    G.T. Mohanraj
    Flexible conductive polymer composites were prepared using styrene,butadiene rubber (SBR) as a matrix and conductive carbon black as filler. The filler loading was varied from 10 to 60 phr. The complex AC impedance and electromagnetic interference shielding effectiveness (EMI SE) of the composites were measured at the microwave frequencies of 7.8,12.4 GHz. The effect of variation in filler concentration and measurement frequency on the AC impedance and EMI SE of the composites were investigated. Equivalent circuits describing the conduction behavior of the composites were determined by means of Nyquist plots. The complex electric modulus of the composites was also determined. Increase in the filler loading increased the capacitive nature of the materials. The composites were better defined by a parallel resistor,capacitor circuit in series with a resistor. The EMI SE was found to pass through a maximum with increase in frequency. However, with the increase in filler loading and sample thickness of the material, the EMI SE was found to increase continuously. POLYM. ENG. SCI., 46:1342,1349, 2006. © 2006 Society of Plastics Engineers. [source]

    ChemInform Abstract: Lithium Storage Capability of Lithium Ion Conductor Li1.5Al0.5Ge1.5 (PO4)3.

    CHEMINFORM, Issue 34 2010
    J. K. Feng
    Abstract The title compound with a NASICON structure is prepared by solid state reaction of stoichiometric amounts of Li2CO3, Al2O3, Ge, and NH4H2PO4 (Pt crucible, 700 and 950 °C, 2 h each) and characterized by XRD, cyclic voltammetry, AC impedance, DC conductivity measurements, and battery tests. [source]

    ChemInform Abstract: Determination of the Sodium Ion Transference Number of the Dion,Jacobson-Type Layered Perovskite NaCa2Nb3O10 Using ac Impedance and dc Methods.

    CHEMINFORM, Issue 24 2002
    V. Thangadurai
    Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

    Synthesis and Characterization of Nanostructured Manganese Dioxide Used as Positive Electrode Material for Electrochemical Capacitor with Lithium Hydroxide Electrolyte

    CHINESE JOURNAL OF CHEMISTRY, Issue 1 2008
    An-Bao YUAN
    Abstract A nanostructured manganese dioxide electrode material was prepared using a solid-reaction route starting with MnCl2·4H2O and NH4HCO3, and its electrochemical performance as a positive electrode for MnO2/activated carbon hybrid supercapacitor with 1 mol·L,1 LiOH electrolyte was reported. The material was proved to be a mixture of nanostructured , -MnO2 and , -MnO2 containing some bound water in the structure, which was characterized by X-ray diffraction analysis, infrared spectrum analysis, and transmission electron microscope observation. Electrochemical properties of the MnO2 electrode and the MnO2/AC capacitor were investigated by cyclic voltammetry, ac impedance and galvanostatic charge/discharge methods. Experimental results showed that the MnO2 electrode exhibited faradaic pseudocapacitance behavior and higher specific capacitance in 1 mol·L,1 LiOH electrolyte. The MnO2/AC hybrid capacitor with 1 mol·L,1 LiOH electrolyte presented excellent rate charge/discharge ability and cyclic stability. [source]