Bulk electrical properties

Sala and Trifiro [274] give evidence that dissolving antimony in Sn02 increases and stabilizes the number of free electrons. 

Morrison [232,233] finds that the free energy of electrons in the bulk phase (Fermi energy) is about the same for different selective and active catalysts. He notes that this value is very near (or just above) the electron exchange level of oxygen and hence makes reduction of oxygen possible. 

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Electrica.1 Properties. The bulk electrical properties of the parylenes make them excellent candidates for use in electronic constmction. The dielectric constants and dielectric losses are low and unaffected by absorption of atmospheric water. The dielectric strength is quoted for specimens of 25 p.m thickness because substantially thicker specimens cannot be prepared by VDP. If the value appears to be high in comparison with other materials, however, it should be noted that the usual thickness for such a measurement is 3.18 mm. Dielectric strength declines with the square root of increasing... 

Gleitzer, C. Nowotny, J. Rekas, M. (1991) Surface and bulk electrical properties of the hematite phase. Appl. Phys. A53 310-316... 

Figures 1 and 2 show the bulk electrical properties of the two cured molding compounds. The dielectric constant and dissipation factor were determined before and after moisture exposure. For moisture exposure, the samples were placed in an autoclave at 100% relative humidity, 15 psig, and 250°F for 500 hours. Measurements...

Nelson et al. [16] have shown that the etching solution attacks only the surface regions of the fluorocarbon polymer. They examined a cut section of etched PTFE and, from optically microscopy, determined that the depth of the coloured surface region was about 1 /xm. However, they reported that the bulk electrical properties of the treated and untreated polymer were virtually identical and that their electron diffraction patterns were indistinguishable, indicating that no changes had been induced in the bulk polymer s crystallinity. These observations may be attributed to the thinness of the treated surface layer and thus the properties of the layer are not measured when analytical techniques are employed which monitor the bulk properties of the material. Indeed, Benderley [17] has since reported that the treated layer does have a substantially lower surface resistivity than the untreated material. 

When the emphasis is put on the bulk electrical properties of the material under investigation in comparison with the predictions of theoretical models, ac conductivity plots, i.e., plots of ac conductivity, cr, against frequency, uj, at constant temperature, are well suited for presenting and discussing the results of the ionic conductivity measurements [16,28]. The data are recorded isothermally with variation of the frequency, to, and cr c( ) is calculated from these data (in fact, the real part, of the complex conductivity), e.g., in the admittance presentation (Eq. (2))... 

To define the thennodynamic state of a system one must specify fhe values of a minimum number of variables, enough to reproduce the system with all its macroscopic properties. If special forces (surface effecls, external fields—electric, magnetic, gravitational, etc) are absent, or if the bulk properties are insensitive to these forces, e.g. the weak terrestrial magnetic field, it ordinarily suffices—for a one-component system—to specify fliree variables, e.g. fhe femperature T, the pressure p and the number of moles n, or an equivalent set. For example, if the volume of a surface layer is negligible in comparison with the total volume, surface effects usually contribute negligibly to bulk thennodynamic properties. 

Electrical Properties. Generally, deposited thin films have an electrical resistivity that is higher than that of the bulk material. This is often the result of the lower density and high surface-to-volume ratio in the film. In semiconductor films, the electron mobiHty and lifetime can be affected by the point defect concentration, which also affects electromigration. These effects are eliminated by depositing the film at low rates, high temperatures, and under very controUed conditions, such as are found in molecular beam epitaxy and vapor-phase epitaxy. 

For static electric properties, the bulk property of interest is the dielectric polarization P. The magnitude of P can be estimated from (for example) the Clausius-Mossotti relation... 

The similarity of the results obtained on systems based on nanogranules made of materials with different bulk properties allows one to conclude that the phenomena at issue are connected only with the decreased size of the granules and not with the bulk properties of the material. In fact, when dealing with such small sizes, it is probably impossible to attribute bulk properties to them, because surface states begin to play a dominant role in the electrical properties of such objects. 

Perhaps of greater interest to us are results derived by the same authors71 that relate surface and bulk electronic properties of jellium. Considering two jellium slabs, one extending from —L to -D and the other from D to L, they calculated the force per unit area exerted by one on the other. According to the Hellmann-Feynman theorem, this is just the sum of the electric fields acting... 

See also Methacrylate monomers polymerization data for, 16 279t Methacrylic ester polymers, 16 271-298. See also Methacrylate monomers Methacrylic esters analytical test methods and specifications for, 16 291-293 bulk polymerization of, 16 281-282 chemical properties of, 16 276-277 electrical properties of, 16 276 emulsion polymerization of, 16 285-288 glass transition temperature of, 16 273-274... 

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