Ionic salts glassy

The glassy systems mentioned in Figs. 4.1(h) and 4.2 show that quite complex chemical compositions have been prepared in the glassy state. Up to three basic constituents are present in all ionically conducting glasses network formers, network modifiers and ionic salts, in different proportions. 

From this relationship we may expect to be proportional to the salt thermodynamic characteristics, if u+ and K -,ss have constant values at constant temperature and pressure in a given glassy system. The square root dependency of ionic conductivity on Umy has been experimentally verified over several orders of magnitude. The dissociating species is either a network modifier or a doping salt. Potentiometric (Ravaine and Souquet, 1977) or calorimetric (Reggiani, Malugani and Bernard, 1978)... 

Most work to date has either used soluble anodes or has not considered the anodic reaction. A limited amount of information has been collated on the electrochemical windows of ionic liquids but this tends to be on either platinum or glassy carbon, which is not necessarily suitable for practical plating systems [1], The anodic limits of most liquids are governed by the stability of the anion, although pyridinium and EMIM salts are sometimes limited by the stability of the cation. The widest electrochemical windows are obtained with aliphatic quaternary ammonium salts with fluorous anions. A selection of potential windows is given in Chapter 3. 

Fig. 4 Stability diagram of polyelectrolyte complexes as a function of the ionic strength for systems where (a) t rj Texp and (b) t > texp- On the horizontal axis is the composition of the mixture given. On the vertical axis is the salt concentration (Csan). The L region indicates a liquid state, and the G region the glassy (quenched) state S indicates soluble polyelectrolyte complexes. In the N region, no complexation occurs [1]. (a) is a slight modification of the diagram proposed by Kovacevic et al. [31]...

Electrochemical deposition of Pt or Pt-alloys in an ionomer-coated carbon-based CL is the perfect technique to ensure 100% utilization of the metal nanopartides. Indeed, the deposited metal crystallites are in ionic contact with the ionomer and in electronic contact with the carbon support [57,103,104]. The metallic salt precursorfs) is(are) reduced either at fixed potential or fixed current, with eventually pulses to allow refilling of the Pt/ionomer interface in metallic salt. Similarly to impregnation/chemical reduction, the chemical interactions existing between the carbon support and the metal precursor should be maximized to control the average partide size and the PSD. This technique was applied successfully on basal-plane-oriented graphite [105,106], glassy carbon [107-109], CB particles [103,110-113], and ionomer-coated carbon-based CLs [114]. 

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