Papers by Keyword: AC Impedance

Abstract: In order to study the corrosion mechanism of corrosion inhibitor on Q235 steel in tank sedimentary water, we prepared the simulation solution of sedimentary water which cintained : C1-10.0 g/L, SO42-1.0 g/L, HCO3- 0.75 g/L, Ca2+ 0.35 g/L, Mg2+ 0.2 g/L, according to the ion concentration under the condition of severe local corrosion. then the corrosion inhibitor was added into the solution, and the ac impedance was studied for different corrosion inhibitor by using the CHI660C electrochemical workstation. The results showed that when the zinc chloride compounds with ATMP (15:10), the high frequency area of ac impedance spectrum diagram is single capacitive reactance arc, and the radius of capacitive reactance arc existed concentration-dependent extreme behavior, which indicated that the adsorption film covering the metallic surface reduces the corrosion rate of metal; the radius was pretty small when only the zinc chloride or ATMP was added into the solution. When the compound ratio was 15:15, the radius reached the maximum, the adsorption resistance became bigger, and the adsorption film had good compactness thus the metal was not easy to be corroded. When Zinc chloride, ATMP and HEDP were compounded with 70 mg/L in total, a capacitive reactance arc appears in the high frequency area and a diffusion tail in the low frequency area, when the ratio was 15:7:3, the radius was the largest, and the performance was best.

Abstract: Aluminum doped Zinc Oxide (AZO) layer has been employed as electron acceptor in hybrid solar cell based on Poly(3-hexylthiophene) with inverted structure. AZO layers used in this work were prepared by sol-gel process using two different solvents, namely methanol and methoxyethanol. From X-ray diffraction measurements, AZO layer prepared using methanol solvent (AZO-me) indicates the formation of crystallines with the same (002) orientation, whereas AZO layer prepared using methoxyethanol (AZO-mx) indicates the formation of crystallines with (100), (002), and (101) orientations. The nanomorphology of those AZO layer surfaces was also remarkably different, which might be related to differences in crystal orientation. For both solvents, the photocurrent density-voltage (J-V) characteristics were also affected by the Al ion concentration in AZO layer. However, solar cell with AZO-mx shows better performances in comparison to that of AZO-me with the same Al ion concentration. The observation of performance variations in those fabricated solar cells are suggested to be strongly related with the crystal orientation and nanomorphology of AZO layer. These experimental results then suggest that charge carrier dissociation by AZO layer are significantly influenced by the crystal orientation and nanomorphology of AZO layer, which are affected by the solvent used for preparing the AZO layer.

Abstract: In order to achieve high cleaning efficiency requirement for post Chemical Mechanical Polish (CMP) cleaning in Through Silicon Via (TSV) application due to the aggressive CMP process. More comprehensive wafer defect evaluation techniques are needed to understand the cleaning mechanisms and assist the formulation design process. In this paper, the CSX-T series chemistry is applied to the post CMP cleaning process of various wafer substrates commonly used in TSV integration schemes. The data collected by several techniques are analyzed in detail and compared to demonstrate how and when it can be used in new formulation screening process to ensure good cleaning performance.

Abstract: This paper studies effect of corrosion inhibitor TG201 on electrochemical corrosion behavior of tubular steel HP13Cr by polarization curve test and exchange impedance spectrum method. It analyzes corrosion morphology by SEM. The results show that the increase of compression stress on HP13Cr lead to its self-corrosion potential shifting negatively, then electrochemical corrosion rate increases. Finally, corrosion resistance performance of HP13Cr steel weakens in acidification environment. Effects of compression stress on electrochemical corrosion become weak by adding TG201 inhibitors. And inhibitor efficiency of TG201 has obvious increase. So controlling compression stress has certain influence on inhibitors efficiency.

Abstract: In this paper, carbon black was activated by grafting and coupling respectively. Then the grafted carbon black, coupled carbon black, together with the unmodified carbon black were filled into polypropylene to prepare three kinds of composites respectively. The measurements of Fourier Transform Infrared Spectroscopy (FTIR), melt flow index, and alternating current (AC) impedance were performed on the composites. From the FTIR spectra, it was shown that different groups are bonded to the surface of carbon black after activating treatment For the corresponding conductive composites，it was found that the variation of fluidity with carbon black content and temperature changed after the carbon black activation. The influence of carbon black activation on the AC impedance and fluidity of the composites was analyzed. The scheme describing the interaction between carbon black and polypropylene in composites was given according to the results mentioned above.

Abstract: Abstract: Alloy 600 was studied in different acidic environments with three approaches including Tafel curve method, linear polarization method and AC impedance curve. Experimental results showed that there was greatest corrosion velocity when pH was 4 for preventing film factor; and it was possibly caused by elements corrosion dissolving with different proportional compared with Alloy 600 metallurgical contents.

Abstract: A low-cost organic compound mainly comprising of polyarylate was selected as precursor and a chemical activation method was used to prepare an activated carbon material of large surface area, with which the activated carbon electrodes of high specific capacitance were fabricated for supercapacitor. Impact of activating temperature on the specific capacitance of activated carbon electrode was studied, the relationship between the pore structure, surface area and specific capacitance of activated carbon electrode were discussed. The specific capacitance and ESR (equivalent series resistance ) of the electrode fabricated with the activated carbon prepared at 700°C is 211F.g-1 and 0.2Ω/cm2 in hydrous electrolyte and the 122F/g and 1Ω/cm2 in orgnic electrolyte respectively. Because of the different ion diameter in orgnic and hydrous electrolyte, activated electrode show different electrochemical behavior in cyclic voltammetry examinations.

Abstract: Ceramic solid solutions Bi4MnxV2–xO11–(x/2)–δ in the composition range 0.07 ≤ x ≤ 0.30 were obtained by solid state synthesis. Structural investigations were carried out by using a combination of FT-IR and powder X-ray diffraction technique. Polymorphic transitions (β↔γ and γ′↔γ) were detected by DTA and variation in the Arrhenius plots of conductivity. The solid solutions with composition 0.07 ≤ x ≤ 0.17 are isostructural with the orthorhombic β-phase, and those with x ≤ 0.30 represent tetragonal γ-phase. With increasing Mn concentration, the conductivity of solid solutions increases from 3.684×10-6 (x = 0.07) to 2.467×10-5 (x = 0.17). AC impedance plots show that the conductivity is mainly due to the grain contribution which is evident in the enhanced short range diffusion of oxide ion vacancy in the grains with increasing temperature.

Abstract: The diffusion of charged species in solids is a very important part of the study of the electrical properties of materials. Electrical measurements using alternating current (ac) impedance is a powerful technique to study diffusing species in metal oxides as well as polymers. Three case studies are being presented here whereby the electrical properties of LiTaO3, Poly[2-methoxy-5-(2’-ethylhexyloxy)-(p-phenylenevinylene)] (MEH-PPV) and its composite are being studied using the same ac impedance technique. LiTaO3 is a metal oxide while MEH-PPV is a polymer. They are very different and therefore present very good examples for the versatility and power of ac impedance method. Electrical parameters such as conductivity and conduction behaviours of the conducting species can be extracted from the studies. The kinetics of the diffusing species can be elucidated by using proper analytical techniques.

Abstract: ZnO is a wide band gap semiconductor with many applications such as in solar cells, varistors, and other electrical components. The ZnO material was synthesized using a sol-gel method. The material was characterized using X-Ray diffraction (XRD) and scanning electron microscopy (SEM). The material is pure and single phase. Electron conduction in ZnO nanomaterials was done using alternating current (ac) impedance. The frequency ranges of the measurements used were 1x 10-3 Hz to 1x 106 Hz and the ac impedance measurements were done within a temperature range of 60oC to 100oC. Nyquist plots were drawn and bulk resistances were obtained. Subsequently, conductivity values were calculated and the diffusion characteristics were obtained. From further analysis of the conductivities with temperature, the diffusion of electrons in the material was studied. It was found that the conductivity increased with the increase of temperature which meant that the rate of diffusion of the electrons through the materials also increased. An Arrhenius relation was concluded for the electron diffusion in the ZnO nanomaterials.