Surfaces, electrical behavior

The orientational structure of water near a metal surface has obvious consequences for the electrostatic potential across an interface, since any orientational anisotropy creates an electric field that interacts with the metal electrons. Hydrogen bonds are formed mainly within the adsorbate layer but also between the adsorbate and the second layer. Fig. 3 already shows quite clearly that the requirements of hydrogen bond maximization and minimization of interfacial dipoles lead to preferentially planar orientations. On the metal surface, this behavior is modified because of the anisotropy of the water/metal interactions which favors adsorption with the oxygen end towards the metal phase. 

In the photolithographic process, the geometrical pattern that produces the desired electrical behavior is transferred to the surface of the wafer. 

Additions of BN powder to epoxies, urethanes, silicones, and other polymers are ideal for potting compounds. BN increases the thermal conductivity and reduces thermal expansion and makes the composites electrically insulating while not abrading delicate electronic parts and interconnections. BN additions reduce surface and dynamic friction of rubber parts. In epoxy resins, or generally resins, it is used to adjust the electrical conductivity, dielectric loss behavior, and thermal conductivity, to create ideal thermal and electrical behavior of the materials [146]. 

The initial scan shows indeed a very poor contact (Figure 17.8). At a voltage of 1V the current is below 1 nA and the conductivity is dependent on voltage and also on the location of the contact within the scanned area. After a thermal treatment of 5 min at 200°C the conductivity scan showed excellent conductivity on the whole scan area and at 0.01 V the current amplitude rises to more than 300 nA, so the conductivity increases by more than five orders of magnitude, see Figure 17.9. The reason for this behavior can be described by surface contamination. But the analytical description of the electrical behavior of this surface layer, which is mostly related to water and carbon, is hardly possible. An analytical description of the electri-... 

Equation 3.7 points out that the variation in the electric field strength (-dy/dx) is related to the second power of the inverse of the thickness of the double layer times /, while Equation 3.8 shows that / decays exponentially with respect to distance (jc) from the surface (Fig. 3.23). A plot of ln( // (/0) versus x produces a straight line with slope k, which is the inverse of the double layer thickness. The assumption ij/0 < 25 mV is not applicable to all soil minerals or all soils. Commonly, clay minerals possess more than 25 mV in surface electrical potential, depending on ionic strength. The purpose of the assumption was to demonstrate the generally expected behavior of charged surfaces. 

Colloid behavior in natural soil-water systems is controlled by dispersion-flocculation processes, which are multifaceted phenomena. They include surface electrical potential (El-Swaify, 1976 Stumm and Morgan, 1981), solution composition (Quirk and Schofield, 1955 Arora and Coleman, 1979 Oster et al., 1980), shape of particles, initial particle concentration in suspension (Oster et al., 1980), and type and relative proportion of clay minerals (Arora and Coleman, 1979). When suspended in water, soil colloids are classified according to their settling characteristics into settleable and nonsettleable solids. 

The over-all effect of the methylchlorosilane treatment of steatite is to stabilize the electrical behavior of the surface under widely different conditions of humidity or condensation. The same surface stability is desired in certain types of fluorescent lamps in order to insure dependable starting of the discharge, regardless of the ambient humidity. Such lamps therefore are treated with the methylchlorosilane vapor in order to make the surface water-repellent, in which condition it has a more constant resistivity and a predictable charge distribution. The starting characteristics then are no longer affected seriously by the moisture content of the air. 

Hydroxyl groups ( 3.3). H2O is almost ubiquitous and easily reacts with low-coordinated sites to form OH groups at the surface of MgO. These centers can act as nucleation centers in the growth of metal particles, induce asymmetries in the surface electric field, or exhibit a classical Broensted acid behavior. 

The success in the development of CNT-based elements for nanoelectronics can be achieved when one is able to produce CNT with controllable properties, deposit them on different surfaces and manipulate along the substrate towards the desirable electrode pair with the proper control of the electric contact between CNT and electrodes. We have fabricated samples of nanovaristors and nanotransistors [4] based on CNT and carbon stripes. Their electric behavior has been studied at high temperatures (up to 125°C) and radiation fields up to 1.1610 rad. CNT based transistors can be applied in high sensitive miniaturized... 

The Influence of Different Stresses on the Hydrophobicity and the Electrical Behavior of Silicone Rubber Surfaces... 

Keywords silicone rubber, surface, hydrophobicity, electrical behavior, PDMS... 

Actually there are defined no minimum requirements for the stability or the dynamics of the hydrophobicity of silicone elastomers. The presently existing knowledge has been achieved from long-time field and laboratory tests. Because of the complexity of the stress factors, the results are not always comparable. Thus, systematic laboratory experiments have to be performed to be able to validate the influence of different material parameters. This paper deals with experiments on the influence of single stress parameters on the hydrophobicity. The results are compared with the electrical behavior of droplet layers on the silicone mbber surfaces. 

To obtain a sufficiently high sheet resistance for strain gauges, the thickness of the NiCr layers have to be in the range of 50-100 nm. If the thickness is significantly below 100 nm, surface effects become important for the electrical behavior. In consequence, the electrical properties deviate from the bulk properties [31]. Typically, the resistivity increases with decreasing thickness while the temperature coefficient of the resistance decreases. Another consequence is that the surface... 

The element of indeterminateness in this definition is to a certain extent advantageous, as the borderline between surface interactions which can be regarded as tribological and those which cannot is not firmly established. For example, the interaction between two charged surfaces as they approach each other is ordinarily thought of as electrical behavior. However, as we shall find when we come to the examination of contacting... 

In their classic series of papers, Hodgkin and Huxley gave a quantitative description of the unique electrical behavior of the giant nerve fibers (axons) of squid. This behavior is described in terms of permeability of the surface membrane (measured as conductance per unit area of membrane) to different ion species, particularly Na+ and K+. The current carried by an ion species through the membrane is then calculated from the product of conductance and driving force on them (transmembrane voltage, V, minus ion equilibrium potential). The specific ionic conductances have several unique properties which challenge explanation at the molecular level ... 

A biomembrane surface-biological fluid interface may be regarded as a solid-liquid interface exhibiting electrical behavior similar to that at an electrode-electrolyte solution interface (Pilla, 1974). Similarities between electrode interfaces and biomembranes in contact with aqueous solutions have recently been noted (Berry et al., 1985 Bowden et al., 1985). 

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