Electrical behaviour

Just as the electrical behaviour of a real diatomic molecule is not accurately harmonic, neither is its mechanical behaviour. The potential function, vibrational energy levels and wave functions shown in Figure f.i3 were derived by assuming that vibrational motion obeys Hooke s law, as expressed by Equation (1.63), but this assumption is reasonable only... 

The calomel electrode Hg/HgjClj, KCl approximates to an ideal non-polarisable electrode, whilst the Hg/aqueous electrolyte solution electrode approximates to an ideal polarisable electrode. The electrical behaviour of a metal/solution interface may be regarded as a capacitor and resistor in parallel (Fig. 20.23), and on the basis of this analogy it is possible to distinguish between a completely polarisable and completely non-polarisable... 

To date, the most common tool for clinical assessment of cardiac electrical function is the electro-cardiogram (ECG). It is a dynamic representation, usually obtained from the body surface, of the changes in cardiac electrical behaviour. 

In addition and importantly, even in non-active junctions, when the electrode Fermi level matches the molecular bridge energy levels, resonance phenomena can generate electrical behaviours similar to those of conventional electronic devices, such as rectification [86-89] and negative differential resistance (NDR) [90, 91]. 

By using Hg-electrode-based junctions, the electrical properties of the highly conjugated units of hexa-pen-hexabenzocoronene (HBC) have been characterized [171]. The HBC unit was anchored to the Au metal surface in an Hg-based junction by a decanonanethiol tether (C19), as depicted in Fig. 9. Comparison of the electrical behaviour of three different junctions, whose interfaces are schematized... 

It would therefore be of obvious importance to study the electrical behaviour of a surface liquid-air, since in that case we can determine changes in surface tension directly. Such experiments were already carried out by Quincke, who examined under the microscope the travel of a small air bubble in capillary filled with liquid, in an electric field. The method is therefore substantially cataphoresis, but has the drawback that there is only a minute thickness of liquid between the air surface and the glass wall, and that the portion of liquid film adjacent to the latter also travels in the electric field. Quincke found that air bubbles in water were negatively... 

The motivation for studies to measure the electrical properties of individual DNA molecules is generated by the necessity to map these properties and the electrical behaviour of DNA molecules for the design of future molecular electronic devices, for which DNA would be a promising material. 

The influence of small quantities of arsenic on copper has already been described (p. 55). The thermal conductivity of Cu-As alloys has been investigated,5 as also has the electrical behaviour at temperatures as low as 1-26° Abs., obtained by means of liquid helium 6 whether or not the alloys are supraconduetive at these temperatures has not been definitely determined. The structure of various Cu-As alloys has been investigated by means of the X-rays.7... 

Spark plugs are checked on their dimensions and on the density, porosity and breaking strength of the insulator. Their electrical behaviour is tested in a test engine. 

To understand the electrical behaviour of the LAPS-based measurement, the LAPS set-up can be represented by an electrical equivalent circuit (see Fig. 5.2). Vbias represents the voltage source to apply the dc voltage to the LAPS structure. Re is a simple presentation of the reference electrode and the electrolyte resistance followed by a interface capacitance Cinterface (this complex capacitance can be further simulated by different proposed models as they are described, e.g., in Refs. [2,21,22]). In series to the interface capacitance, the insulator capacitance Cj will summarise the capacitances of all insulating layers of the LAPS device. The electrical current due to the photogeneration of electron-hole pairs can be modelled as current source Ip in parallel to the... 

At low frequencies, the external field induces an alternating voltage which is superposed on the resting (dc) transmembrane potential. As frequencies rise and the membrane capacitance dominates its electrical behaviour, this induced voltage drops to a very low level. 

The relevance of the model is a matter of controversal discussions. Though the chemical reaction is a rather speculative one, one should realize that the special type of nonlinear reaction can be replaced by an other one. The important step is the combined existence of both, a special chemical kinetics and a related electric behaviour. Both terms can be modified, but they must be based on physical laws and the extraordinary dielectric properties of the material. 

Mao, H.-K. Bell, P. M. (1972a) Optical and electrical behaviour of olivine and spinel (Fe2Si04) at high pressure. Interpretation of the pressure effect on the olivine absorption bands of natural fayalite to 20 kb. Crystal field stabilization of the olivine-spinel transition. Ann. Rept. Geophys. Lab., Yearb. 71, 520-8... 

No reference has been made to the type of charge carrier and the equations developed so far in no way depend upon this. However, the electrical behaviour of solids depends very much on whether the charge carriers are electrons, ions or a combination of both. 

In practice ceramics are usually multiphase, consisting of crystalline phases, glasses and porosity. The overall behaviour depends on the distribution as well as the properties of these constituents. A minor phase that forms a layer round each crystallite of the major phases, and therefore results in a 3-0 connectivity system (see Section 2.7.4), can have a major effect. If the minor phase is conductive it can greatly reduce the resistivity of the composite or, if insulating, it can reduce its conductivity. Also, an abrupt change in the mode of conduction at the main phase-intercrystalline phase boundary may introduce barriers to conduction that dominate the overall electrical behaviour. In contrast, minor phases present as small discrete particles, or porosity present as empty cavities, can only modify properties to a minor extent as indicated by one of the mixture relations such as Lichtenecker s rule (see Section 2.7.4). 

A number of trivalent ions with ru radii between 110 and 133 pm, e.g. Bi and La, can substitute on the A site. La3+ confers a low resistivity at low concentrations (<0.5mo.%), and the electrical behaviour is discussed in Section 2.6.2, and Section 4.4.2. It has been studied more widely as a substituent for lead in PbTi03-based compositions. 

The electrical behaviour of some oxides of transition metals (belonging to fourth period) is given in following table. It may be noted that these oxides show wide variation in their electrical behaviour. 

It is often instructive to plot resistivity p versus 1/T in order to get a qualitative picture of electrical behaviour. In FIGURE 1, we compare p versus 1/T data for layers grown by MBE, MOCVD and HVPE. 

Electrical excellent electrical behaviour that remains stable over a wide range of temperatures and frequencies. 

A close connection has been found to exist between passivity and photo-electric behaviour. Thus dry, active iron is found to exhibit a considerably higher photo-electric activity than the metal rendered passive by immersion in concentrated nitric acid or by anodic polarisation in dilute sulphuric acid and this is regarded as supporting the gaseous film theory.6... 

Negative colloidal ferric hydroxide may be converted into the positive colloid by adding it to a very dilute solution of sodium hydroxide (0 005-normal) with constant shaking. In order to account for this amphi-electrical behaviour, it is suggested that the potential difference at the surface of colloidal particles is due to adsorption of ions from the solution. Hence the sign depends upon whether cations or anions are in excess in the layers nearest the particles.5... 

In the remainder of this chapter we outline the main features of polymer structure and its relation to electrical properties, as a basis for the subsequent more detailed explanation and discussion of electrical behaviour. 

Interdiffusion of saturated solutions (as opposed to electrocrystallization) is another method for obtaining crystals of the potentially conducting salts. In most of the preparations of TTF[Pd(dmit)2]2 (dmit 3-Xn, X, Y, Z = S) by diffusion of (TTF)3(BF4)2 and (n-Bu2N)[Pd(dmit)2] mainly black shiny needles of the a phase were obtained. However, some experiments yielded, in addition, the so-called a phase (due to its structural similarity to the a phase, but different electrical behaviour), and occasionally a third 5 phase of plate-shaped crystals could also be physically separated from the batch (Legros and Valade 1988 Cassoux et al. 1991). ... 

Effects of porous solid structures on the electrical behaviour prediction key of transport properties in sedimentary reservoir rock... 

This paper reports an investigation of the effects of porous solid structures on their electrical behaviour at different frequencies (from 100 Hz to 100 kHz). For that, we study different parameters such as formation resistivity factor, cementation factor, chargeability, resistivity index and saturation exponent. Different porous solid structures are quantified from the petrographic image analysis and Hg-injection technique. Then, by using different models we obtain the permeability prediction from the electrical behaviour and structure parameters. 

The complex electrical behaviour of porous solids can be characterized by the dependance of the complex resistivity and conductivity on frequency as well as the water content, the pore... 

Fig. 1 Different primary and secondary textures used in this study, their pore network structures and electrical behaviour. Hg-injection curves give the ditribution of Hg-saturation versus pore-throat diameter. Z the complex electrical impedance vector 9 phase angle by which current and voltage are shifted M-W mudstone-wackestone textures P-G packstone-grainstone texture G grainstone C crystal carbonate.

Two models were tested to predict the permeability from the electrical behaviour and microstructure parameters of porous solids. 

The electrical behaviour versus frequency for different porous solids textures is given in Figure 1. The complex impedance Z and phase angle 6 decrease with a frequency ranging from 100 Hz to 100 kHz for any porous solids texture at full water saturation. However, the... 

A particularly important question involves the understanding of the role of crystal defects in the peculiar electrical behaviour of ice 4. Upon the application of an electric field, the solid becomes polarized by the thermally activated reorientation of the molecular dipoles. Niels Bjerrum postulated the existence of orientational defects, which represent local disruptions of the hydrogen-bond network of ice 4, to explain the microscopic origin of this phenomenon. 

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