Special Electrical Properties

The special electrical properties of a-AgI inevitably led to a search for other solids exhibiting high ionic conductivity preferably at temperatures lower than 146°C. The partial replacement of Ag by Rb, forms the compound RbAgJs. This compound has an ionic conductivity at room temperature of 25 S m , with an activation energy of only 0.07 eV. The crystal structure is different from that of a-AgI, but similarly the Rb and T ions form a rigid array while the Ag ions are randomly distributed over a network of tetrahedral sites through which they can move. 

A different subclass of unsaturated hydrocarbon type polymers is formed by polyacetylenes. This type of polymer contains conjugated double bonds in a linear structure, and due to their special electrical properties they have been the subjects of numerous studies including some on thermal stability. 

This approach has interesting potentialities as a research tool for studying mixing. Although the assumptions inherent in Forscher s article require a rather idealized system, it may be possible to determine from conductivity measurements whether very fine powders are randomly mixed with one another. This could be done, by calculating at approximately what concentration continuity could be achieved, and then determining whether this were obtained, or whether the concentration needed for continuity was far in excess of that theoretically required. Particularly where the aim of mixing is to achieve some sort of special electrical property, this approach would appear to have potentialities. 

The technology of plasma formation of metal-containing polymers in the form of thin films dates from 1963, when Bradley and Hammes(15) prepared specimens from some forty different materials, and studied their electrical conductivities. Included in the study were organic compounds of iron, tin, titanium, mercury, selenium, and arsenic. The presence of a metal or transition element in the polymer did not lead to special electrical properties compared to the purely organic polymers studied. 

In addition to these four fundamental parameters, special electrical properties are recognised like piezo-, pyro-, ferro- and tribo-electricity and photo voltaic/conducting properties. The contribution in this chapter will be limited to three of the four fundamental parameters AC measurements (1A/1B) and DC measurements (2A). Besides, attention will be given to a kind of combination of AC and DC measurements the thermally stimulated discharge (TSD) analysis technique. An analysis technique used to detect relaxation phenomena in organic and anorganic materials. 

The molecules concerned in the formation of surface films are usually dipolar, so that the interface acquires special electrical properties. These are susceptible of rapid measurement and thus provide... 

Solid-state systems of particular interest in this book are conductive polymers with the ability to occlude dopants entering the bulk of the polymer sample, thus conferring on it its special electrical properties. Some of these properties are a consequence of the mobility of the dopant ions in the host polymer material, and these properties are responsible for such technological applications as battery electrodes,ion gates, and electrochromic devices, which depend on a field-induced oxidation of the polymer specified by its doping level. Various diffraction methods and tunnelling electron microscopy reveal that these... 

Water, hydroxyl, and hydrogen ions have very special electrical properties. Water is strongly polar, but it is also to a small extent an electrolyte in itself. From Table 2.2, we see that the intrinsic conductivity is low, but it is not zero. The small rest conductivity is due to a protonic self-ionizing process. There is a small statistical chance that a water molecule transfers one of its protons to another water molecule in the following way ... 

Metallic, semiconducting and other special electrical properties... 

ASTM F1701-12, Standard Specification for Unused Polypropylene Rope with Special Electrical Properties. 

Barium titanate-sintered ceramics are developed with the objective of producing materials with special electrical properties, particularly a high dielectric constant. Barium titanate-based sintered ceramics are produced with... 

Electriad and dielectric behaviour of polymers reflect macromolecular structure and motion, both in solution and the solid state. Some polymers whidt have special electrical properties may have commaical potential. Mention need ordy be made of polymer electrets, pyro-electrk polymers, photo-conductive polymers as used In ctro-imaging, and conductive poly mas to indicate tR expansion of use over that of insulators. The separation of electrical behaviour into didectric and btdk conductive properties is convenient and has been followed in this review. 

The resin, catalyst, and microhalloons are mixed to form a mortar which is then cast into the desirable shape and cured. Very specialized electrical and mechanical properties may be obtained by this method but at higher cost. This method of producing cellular polymers is quite appHcable to small quantity, specialized appHcations because it requires very tittle special equipment. 

R. Bartnikas, "Engineering Dielectrics Vol. II A—Electrical Properties of SoHd Insulating Materials Molecular Stmcture and Electrical Behavior," ASTM Special Technical Publication 783, 1983, Chapts. 1—5, pp. 3—515. 

Antioxidants are used to retard the reaction of organic materials with atmospheric oxygen. Such reaction can cause degradation of the mechanical, aesthetic, and electrical properties of polymers loss of flavor and development of rancidity ia foods and an iacrease ia the viscosity, acidity, and formation of iasolubles ia lubricants. The need for antioxidants depends upon the chemical composition of the substrate and the conditions of exposure. Relatively high concentrations of antioxidants are used to stabilize polymers such as natural mbber and polyunsaturated oils. Saturated polymers have greater oxidative stabiUty and require relatively low concentrations of stabilizers. Specialized antioxidants which have been commercialized meet the needs of the iadustry by extending the useflil Hves of the many substrates produced under anticipated conditions of exposure. The sales of antioxidants ia the United States were approximately 730 million ia 1990 (1,2). 

The mechanical and electrical properties of selected high strength aUoys in cast and wrought forms are provided in Table 5. A similar compilation for the high conductivity aUoys is given in Table 6. The mechanical properties shown in the tables correspond to standard hardening times and temperatures and therefore are close to peak conditions. Considerable latitude exists for achieving a wide variety of special mechanical and electrical property combinations. 

In the broad range of ceramic materials that are used for electrical and electronic apphcations, each category of material exhibits unique property characteristics which directiy reflect composition, processing, and microstmcture. Detailed treatment is given primarily to those property characteristics relating to insulation behavior and electrical conduction processes. Further details concerning the more specialized electrical behavior in ceramic materials, eg, polarization, dielectric, ferroelectric, piezoelectric, electrooptic, and magnetic phenomena, are covered in References 1—9. 

Because of the increased shedding with these alloys, pure leaf separation is hardly suitable. Separations with supporting glass mats or fleeces as well as microfiber glass mats provide technical advantages, but are expensive and can be justified only in special cases. Also under these conditions of use the microporous polyethylene pocket offers the preferred solution [40]. Lower electrical properties at higher temperatures, especially decreased cold crank duration, are battery-related the choice of suitable alloys and expanders gains increased importance. 

Other areas such as static electricity and its use and control were not discussed since they represent a different type of application (2). As new materials became available and the electrical art continued to develop, the uses for plastics in electrical applications has increase both in the basic application as a dielectric and in special applications using the special intrinsic properties of the plastics. 

These considerations lead to the assumption that the practical aspects of the problem lie in the possibility of obtaining PCS-based thermally resistant materials, catalysts for some chemical reactions, antioxidants, stabilizers, photochromic substances, and materials combining valuable mechanical properties with special electrical (particularly semiconductive) properties. 

Besides these special physical properties, hydrogen-bonded liquid water also has unique solvent and solution properties. One feature is high proton (H ) mobility due to the ability of individual hydrogen nuclei to jump from one water molecule to the next. Recalling that at temperatures of about 300 K, the molar concentration in pure water of H3O ions is ca. 10 M, the "extra" proton can come from either of two water molecules. This freedom of to transfer from one to an adjacent "parent" molecule allows relatively high electrical conductivity. A proton added at one point in an aqueous solution causes a domino effect, because the initiating proton has only a short distance to travel to cause one to pop out somewhere else. 

Schultz H, Lehmann H, Rein M, Hanack M (1991) Phthalocyaninatometal and Related Complexes with Special Electrical and Optical Properties. 74 41-146 Schutte CJH (1971) The Ab-Initio Calculation of Molecular Vibrational Frequencies and Force Constants. 9 213-263... 

---