| 1. |
- Sathirachinda, Namurata, et al.
(författare)
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SKPFM Study of Chromium Nitrides in 2507 Super Duplex Stainless Steel : Implications and Limitations
- 2011
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Ingår i: Electrochimica Acta. - Oxford : Elsevier BV. - 0013-4686. ; 56:4, s. 1792-1798
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Tidskriftsartikel (refereegranskat)abstract
- The effect of chromium nitrides on localized corrosion resistance of 2507super duplex stainless steel was investigated in this study. The Voltapotential difference measured with scanning Kelvin probe force microscopy(SKPFM) indicates that chromium nitrides with the size range of 80‐230 nmprecipitated isothermally at the ferrite/austenite phase boundaries maydetrimentally affect the corrosion resistance due to the observed local Voltapotential drop at the phase boundaries. Small quenched‐in nitrides with thesize range of 50‐100 nm formed in the centre of the ferrite phase, on theother hand, may have small or no adverse effect on the corrosion resistancesince they showed no difference in Volta potential relative to the matrix.
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| 2. |
- Adebahr, Josefina, 1973, et al.
(författare)
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Ab initio calculations, Raman and NMR investigation of the plastic crystal di-methyl pyrrolidinium iodide
- 2003
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Ingår i: Electrochimica Acta. - 0013-4686. ; 48:14-16, s. 2283-2289
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Tidskriftsartikel (refereegranskat)abstract
- Above 110 °C the symmetric di-methyl-pyrrolidinium iodide salt forms a plastic crystal phase of interest in the area of new electrolyte materials. In this study ab initio calculations of this material has been conducted in order to assign the vibrational spectra. Raman spectroscopy measurements on the solid salt as well as on the salt dissolved in different solvents has been performed and these have been compared to the theoretical spectra. Furthermore, Raman spectra as a function of temperature have been recorded to investigate possible changes in inter-ionic interaction and/or structure through the phase transition. 1 H NMR linewidth measurements as a function of temperature showed a large decrease in linewidth above 100 °C, attributed here to an increase in mobility in agreement with a previously reported phase transition at ∼ 110 °C. © 2003 Elsevier Science Ltd. All rights reserved.
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| 3. |
- Adebahr, Josefina, 1973, et al.
(författare)
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Enhancement of ion dynamics in PMMA-based gels with addition of TiO2 nano-particles
- 2003
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Ingår i: Electrochimica Acta. - 0013-4686. ; 48:14-16, s. 2099-2103
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Tidskriftsartikel (refereegranskat)abstract
- Solvent and ion dynamics in PMMA based gels have been investigated as a function of the loading of nanosized TiO 2 particles. The gels have a molar ratio of 46.5:19:4.5:30 of ethylene carbonate (EC), propylene carbonate (PC), lithium perchlorate and PMMA, respectively. A series of samples with 0, 4, 6 and 8 wt.% TiO 2 filler were investigated. The diffusion coefficients for the lithium ions and for the two solvents (EC and PC) were investigated by pfg-NMR. It was shown that the addition of filler to the gel electrolytes enhances the diffusion of the cations, while the diffusion of the solvents remains constant. Raman measurements show no significant changes in ion-ion interactions with the addition of fillers, while the ionic conductivity is seen to decrease. However, the sample with 8 wt.% TiO 2 had a conductivity close to that of the unfilled sample. © 2003 Elsevier Science Ltd. All rights reserved.
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| 4. |
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| 5. |
- de Santos, A, et al.
(författare)
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Nile blue adsorbed onto silica gel modified with niobium oxide for electrocatalytic oxidation of NADH
- 2002
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Ingår i: Electrochimica Acta. - 0013-4686. ; 47:20, s. 3351-3360
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Tidskriftsartikel (refereegranskat)abstract
- A study of modified carbon paste electrode employing Nile blue (NB) adsorbed on silica gel modified with niobium oxide (SN) for electrocatalytic oxidation of reduced nicotinamide adenine dinucleotide (NADH) is described. The adsorbed organic dye on SN was used to prepare a modified carbon paste electrode to investigate its electrochemical properties. The formal potential (E-o') of the adsorbed NB (-230 mV vs. saturated calomel electrode, SCE) showed a shift of 70 mV towards a more positive potential value, compared to NB dissolved in aqueous solution. In solutions with pH between 6.0 and 8.0 did stability and E-o' remained almost constant. However, for a solution pH lower than 6.0 the E-o' was affected by the acidity of the contacting solution, shifting the E-o' towards more positive values. For the solution pHs between 6.0 and 8.0 the electrocatalytic activity remained almost constant. A linear response range for NADH between 1.0 x 10(-5) and 5.2 x 10(-4) mol 1-1, at pH 7.0, was observed for the electrode, with an applied potential of -200 mV versus SCE. The formation of an intermediate charge transfer (CT) complex was proposed to the CT reaction between NADH and adsorbed NB. The heterogeneous electron transfer rate, k(obs), was 1400 M-1 s(-1) and the apparent Michaelis-Menten constant, was 0.21 mM at pH 7.0 evaluated from rotating disk electrode (RDE) experiments with an electrode coverage of about 5.2 x 10(-9) mol cm(-2). The increase in the reaction rate between NADH and the immobilized NB compared to those obtained with dissolved NB was assigned to the shift of the E-o' towards more positive values. (C) 2002 Elsevier Science Ltd. All rights reserved.
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| 6. |
- Dérand, Helene, et al.
(författare)
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Anionic Graft Copolymers Containing Poly(ethylene oxide)
- 1995
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Ingår i: Electrochimica Acta. - 0013-4686. ; 40:13-14, s. 2413-2416
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Tidskriftsartikel (refereegranskat)abstract
- Anionic graft copolymers were prepared through ring-opening anhydride reactions between poly(ethylene oxide) monomethyl ethers (MPEG) and copolymers of maleic anhydride and styrene (SMA), methyl vinyl ether (MEMA) and ethylene (EMA), respectively. The carboxylic acid groups in the graft copolymers were neutralized with KOH, and films were prepared by solution casting. The materials were characterized by FTIR, NMR and DSC. Ionic conductivity and electrical relaxation have been studied as well. The EMA-MPEG 2000 graft copolymer showed the highest conductivity, sigma = 3 x 10(-5) S cm(-1) at 80 degrees C.
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| 7. |
- Gavelin, Patrik, et al.
(författare)
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Amphiphilic polymer gel electrolytes. 3. Influence of the ionophobic-ionophilic balance on the ion conductive properties
- 2001
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Ingår i: Electrochimica Acta. - 0013-4686. ; 46:10-11, s. 1439-1446
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Tidskriftsartikel (refereegranskat)abstract
- Gel electrolytes based on amphiphilic copolymethacrylates containing ethylene oxide (EO)(n) side chains as ionophilic units and fluorocarbon (CF,), side chains as ionophobic units showed a substantial increase in ion conductivity, as compared to corresponding gels based on homopolymers of (EO),, methacrylate. The highest ion conductivity was found for a gel based on a copolymer composed of 24 wt% of (EO)(9) methacrylate and 76 wt% of fluorocarbon methacrylate. This gel contained 70 wt% of 1 M LIPF6 gamma -butyrolactone, and had an ion conductivity of 4.0 mS/cm at 20 degreesC, and 1.0 mS/cm at - 20 degreesC. It was found that gels based on fluorocarbon-containing copolymers having (EO), side chains had higher ion conductivities than gels based on copolymers containing (EO), side chains. The study showed that it is important to control the ionophobic-ionophilic balance of the amphiphilic copolymer in order to achieve high ion conductivities in the gel electrolyte. It is very likely that the ionophobic side chains of the copolymer associated to form microdomains in the electrolyte. It is also likely that longer EO chains increased the stability of these microdomains in the electrolyte. However, strong lithium ion coordination to EO chains above a critical chain length may have suppressed the ion conductivity of the gels.
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| 8. |
- Jannasch, Patric
(författare)
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Phase behavior and ion conductivity of electrolytes based on aggregating combshaped polyethers
- 2001
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Ingår i: Electrochimica Acta. - 0013-4686. ; 46:10-11, s. 1641-1649
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Tidskriftsartikel (refereegranskat)abstract
- The influence of temperature and salt concentration on the properties of solid polymer electrolytes based on lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) complexed by combshaped polyethers has been studied. The combshaped polyethers consisted of styrenic backbone polymers carrying pendant poly(ethylene oxide) (PEO) or poly(ethylene oxide-co-propylene oxide) (PEOPO) side chains terminated by hydrocarbon (C-16) chain ends. Analysis by DSC and polarized light microscopy showed that the structure and composition of the side chains had a large effect on the crystallization behavior of the electrolytes. For example, a slow crystallization process was noted in electrolytes containing PEO side chains after storage at ambient temperature. This transition was not observed in corresponding electrolytes containing PEOPO side chains. Polymer aggregation by phase separation of the hydrocarbon chain ends was indicated in all electrolytes by narrow melt endotherms. A maximum conductivity of 10(-4.6) S/cm at 20 degreesC, and 10(-3.2) S/cm at 80 degreesC, was found at [Li]/[O] = 0.050 for an electrolyte based on a polyether having side chains containing 20 wt% propylene oxide. The temperature dependence of the ionic conductivities was well described by Vogel-Tamman-Fulcher equations in the absence of crystallinity.
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| 9. |
- Johansson, Patrik, 1969, et al.
(författare)
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An ab initio approach to the single ion transport in crystalline LiIPF6PEO6
- 2003
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Ingår i: Electrochimica Acta. - 0013-4686. ; 48:14-16, s. 2279-2281
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Tidskriftsartikel (refereegranskat)abstract
- The lithium ion transport in crystalline LiPF 6 PEO 6 has been modeled by ab initio electronic structure calculations. The activation energy values obtained using a molecular model correspond excellently to experimental values from conductivity measurements. Based on the present results structural modifications in order to further enhance the single ion conductivity are suggested. © 2003 Elsevier Science Ltd. All rights reserved.
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| 10. |
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