Electrical polarization, morphological

The dependence of the drift mobility p on the electric field is represented by formula p (p-E1/2/kTcf) which corresponds to the Pool-Frenkel effect. The good correspondence between experimental and theoretical quantity for Pool-Frenkel coefficient 3 was obtained. But in spite of this the interpretation of the drift mobility in the frame of the Coulombic traps may be wrong. The origin of the equal density of the positive and negative traps is not clear. The relative contribution of the intrinsic traps defined by the sample morphology is also not clear [17,18]. This is very important in the case of dispersive transport. A detailed analysis of the polymer polarity morphology and nature of the dopant molecules on mobility was made by many authors [55-58]. 

The aim of these studies is to understand and control the electrical properties of surfaces on a micrometric scale, that might be extremely useful for the application of these materials in the field of liquid crystal display (LCD) technology. In fact, it is well known that the LC anchoring properties depend not only on the substrate morphology but also on its electrical properties [68]. The electric polarization in nematic and other non-polar liquid crystals has essentially three origins flexoelectricity [65], orderelectricity [66,67] (related to the gradient in the order parameter) and the polarization of the substrate... 

If the combination of X-ray and morphological evidence does not determine the space-group uniquely, additional information may be sought by tests for piezo-electric and pyro-electric properties, and by an optical examination for any evidence of rotation of the plane of polarization. (See Chapter VIII.) The results of such tests may settle the matter, since only certain crystal classes have these properties. Only positive results are decisive the apparent absence of piezo-electric or pyro-electric effects may be due to feeble phenomena. 

Typical values of electrical properties of the homopolymer without additives and treatments are in the Table 3.8. The values can be substantially changed by the type of cooling and post-treatments, which determine the morphological state of the polymer. Dielectric constants as high as 17 have been measured on oriented samples that have been subjected to high electrical fields (poled) under various conditions to orient polar crystalline form.74... 

Besides crystal orientation and surface morphology, the termination of the ZnO crystallites is another important parameter for the optimization of ZnO films High piezo-electric coupling coefficients can only be achieved if the ZnO crystallites have a uniform polarity. There are only a few processes that allow the polarity of the ZnO films to be assessed. 

In conclusion, in most polar aprotic Li salt solutions, the morphology of Li electrodes upon charge-discharge cycling is very rough. The electrodes become covered with reactive dendrites that can be readily disconnected electrically from the bulk. Nonuniform Li dissolution further enhances the fractal structure of the electrode surface. These situations were recently rationalized and well explained by theoretical approaches and calculations [259,260],... 

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