Membranes, impedance diagram

Fig. 10.16 Impedance diagram for the AsPh4BPh4/PVC/NOPE membrane in contact on one side with 0.01 M AsPh4CI in 0.1 M NaCl and on the other side with 0.1 M CaClj at...

Eontanella and co-workers studied the effect of high pressure variation on the conductivity as well as the H, H, and O NMR spectra of acid form Nafionl 17 membranes that were exposed to various humidities. Variation of pressure allows for a determination of activation volume, A V, presumably associated with ionic and molecular motions. Conductivities (a) were obtained from complex electrical impedance diagrams and sample geometry, and A V was determined from the slope of linear isothermal In a versus p graphs based on the equation A E = —kJ d In a/d/j] t, where p is the applied pressure. At room temperature, A Ewas found to be 2.9 cm mol for a sample conditioned in atmosphere and was 6.9 cm mol for a sample that was conditioned in 25% relative humidity, where the latter contained the lesser amount of water. 

Impedance diagrams measured during a Hj sorption experiment on a 125 pm thick Pd Agjs membrane (a) before and (b) after recrystallization using the same driving force AP= 150 mbar at T= 150°C. 

Figure 14.3 Representative impedance diagram of a 10%Sro,95FeosCoo303 a - 90%Ceo,9 Gdo.i02-5 membrane measured under air at 150°C. (image adapted from Kim et al. (64).)...

FIGURE 10.1 A schematic diagram for a typical electrode system for potentiometric pH measurements. A potential is established on the pH sensitive membrane-solution interface of a pH electrode that responds to the activity or concentration of hydrogen ions in the solution. The reference electrode has a very stable half-cell potential. The cell potential, which is proportional to the pH in the test solution, is measured using a high input impedance voltmeter between the pH electrode and the reference electrode. 

Figure 5.22. Bode diagram of the measured impedance spectra, PEM fuel cell (hot-pressed, as-received E-TEK electrodes) at 80°C, at different cell voltages (o) OCV (984 mV), ( ) 901 mV, (A) 797 mV [22], (Reprinted from Electrochimica Acta, 43, Wagner N, Schnumberger W, Muller B, Lang M. Electrochemical impedance spectra of solid-oxide fuel cells and polymer membrane fuel cells, 3785-93, 1998, with permission from Elsevier and from the authors.)...

The second technique involves using a four probe apparatus, similar to that described by Cahan and Wainright. The membrane sample is placed in an PTFE apparatus which is equipped with two platinum strips in contact with the film, as shown in Fig. 1.115. Two platinum electrodes in a fixed geometry (distance of 1.026 cm) were placed on the surface of the film to measure the membrane potential and capacitance. Conductivity measurements could be obtained by utilizing complex impedance plots, which employ a circuit diagram... 

FigJ.14 Schemai.% diagram of a FI manifold for liquid-liquid extraction flame atomic absorption spectrometry. P, pump RG. reagent S, aqueous sample SG, phase segmentor, D, displacement bottle E, extraction coil PS, membrane phase separator R, restrictor or impedance coil W, waste V, injector valve AAS, flame atomic absorption spectrometer fl4]. 

Figure 2.31 Schematic diagram of the immobilization and hybridization of DMA on Au/ nanoPAN/GCE. (Reprinted with permission from Analytica Chimica Acta, Enhanced Sensitivity for deoxyribonucleic acid electrochemical impedance sensor Gold nanoparticle/polyaniline nanotube membranes by Y. Eeng, T. Yang, W. Zhang, C. Jiang and K. Jiao, 616, 2, 144-151. Copyright (2008) Elsevier Ltd) (See colour Plate 1)...

In the two-point probe configuration, two electrodes serve as both current and voltage sensing probes, as shown in Fig. 5.11 [60] in the diagram, open window A allows the membrane to be exposed to the environment. For this method, the current and voltage are measured from two identical probes. Because the electrode/membrane interfacial impedance is always included in... 

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