Thin-Film Bulk Reaction

Soiid-state reactions leading to useful energy storage or conditioning processes have been intensively investigated during the last two decades from a battery development point of view (19-21). 

The amount of charge stored in an electrode is a function of the potential, and is related to the amount of stored energy  

We can therefore define an equivalent integral capacitance per electrode Eq. (11) C = 2U/AE2 

When E vs. Q is as shown in Fig. 4a, then clearly the differential capacitance can be very large. If operation over a narrow potential range is required, then very high capacitances can be obtained. 

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Compounds in groups IIA-IVB may be prepared in bulk form by direct reaction and grown by gradient freeze or Bridgman techniques. Thin-film direct reaction is capable of making MgaSi in epitaxial form on silicon. ... 

Reaction-diffusion systems can readily be modeled in thin layers using CA. Since the transition rules are simple, increases in computational power allow one to add another dimension and run simulations at a speed that should permit the simulation of meaningful behavior in three dimensions. The Zaikin-Zhabotinsky reaction is normally followed in the laboratory by studying thin films. It is difficult to determine experimentally the processes occurring in all regions of a three-dimensional segment of excitable media, but three-dimensional simulations will offer an interesting window into the behavior of such systems in the bulk. 

Feast, W. J. et al J. Chem. Soc., Chem. Comm., 1985, 202-203 The second stage of an improved synthesis of poly(acetylene), which involves disproportionation of a soluble polymer by heating a thin film at 75°C to give 1,2-bis(trifluoromethyl)benzene and poly(acetylene), must not be done in bulk because the reaction then becomes explosive. The earlier synthesis by direct polymerisation of acetylene was considerably more dangerous... 

Water is involved in most of the photodecomposition reactions. Hence, nonaqueous electrolytes such as methanol, ethanol, N,N-d i methyl forma mide, acetonitrile, propylene carbonate, ethylene glycol, tetrahydrofuran, nitromethane, benzonitrile, and molten salts such as A1C13-butyl pyridium chloride are chosen. The efficiency of early cells prepared with nonaqueous solvents such as methanol and acetonitrile were low because of the high resistivity of the electrolyte, limited solubility of the redox species, and poor bulk and surface properties of the semiconductor. Recently, reasonably efficient and fairly stable cells have been prepared with nonaqueous electrolytes with a proper design of the electrolyte redox couple and by careful control of the material and surface properties [7], Results with single-crystal semiconductor electrodes can be obtained from table 2 in Ref. 15. Unfortunately, the efficiencies and stabilities achieved cannot justify the use of singlecrystal materials. Table 2 in Ref. 15 summarizes the results of liquid junction solar cells prepared with polycrystalline and thin-film semiconductors [15]. As can be seen the efficiencies are fair. Thin films provide several advantages over bulk materials. Despite these possibilities, the actual efficiencies of solid-state polycrystalline thin-film PV solar cells exceed those obtained with electrochemical PV cells [22,23]. 

Solid-state NMR spectroscopy was also used to examine the post reaction behavior of pTrMPTrA samples prepared in bulk as thin films, as described in the experimental. All of the spectra in this aging study required a minimum of 720 scans on approximately 50 mg of sample with a 100 s pulse delay to achieve adequate signal/noise. Under these conditions, reliable peak areas could be obtained from the curve fits of the carbonyl region. Figure 3 depicts the evolution of the solid state spectrum of the sample stored under N2 over time and upon heating. The area of the peak at 174 ppm for the carbonyl adjacent to the reacted double bond increases as the peak at 166 ppm for pendant unsaturation decreases. The results of the aging study are given in Table I. 

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