Dielectric characteristics

The composition of an optoelectronic memory card (eg. Laser Card of Drexler Technology Corp.) (162) is outlined in Figure 21 (163). Primary elements are polycarbonate foils with thicknesses of 250 to 400 )Tm, respectively, that are employed because of their high operating temperature and their good mechanical, optical, and dielectric characteristics. The OMC can be used as a ROM or a WORM media. Both possibiUties of information deposition can be used separately or in combination. 

Electrical Properties. AH polyolefins have low dielectric constants and can be used as insulators in particular, PMP has the lowest dielectric constant among all synthetic resins. As a result, PMP has excellent dielectric properties and alow dielectric loss factor, surpassing those of other polyolefin resins and polytetrafluoroethylene (Teflon). These properties remain nearly constant over a wide temperature range. The dielectric characteristics of poly(vinylcyclohexane) are especially attractive its dielectric loss remains constant between —180 and 160°C, which makes it a prospective high frequency dielectric material of high thermal stabiUty. 

However, fluorocarbon compounds might be of considerable interest for LB-layer fabrication. Their dielectric and mechanical characteristics and thermal and chemical stability are not inferior to those of polyimides, and highly developed synthesis technology makes it possible to create systems with various predictable properties. Such films have been found to demonstrate a high degree of perfection and excellent dielectric characteristics.69,70... 

Fig. 4.8 Temperature dependence of the dielectric characteristic times obtained for PB for the a-relaxation (empty triangle) for the r -relaxation (empty diamond), and for the contribution of the -relaxation modified by the presence of the a-relaxation (filled diamond). They have been obtained assuming the a- and -processes as statistically independent. The Arrhenius law shows the extrapolation of the temperature behaviour of the -relaxation. The solid line through points shows the temperature behaviour of the time-scale associated to the viscosity. The dotted line corresponds to the temperature dependence of the characteristic timescale for the main peak. (Reprinted with permission from [133]. Copyright 1996 The American Physical Society)...

Amines were one of the first hardeners of epoxy resins 1 12), and at present they retain their leading position among all known hardeners of this type. The amine hardeners will most likely also be used in the future because they are fairly accessible, highly reactive, and their properties can be readily modified. The mechanical properties of the cured resins obtained are far better than those of the known polymer binders 2 -4), they have high dielectric characteristics, chemical resistance, etc. 

Dielectric Characteristics. Fig. 30 reveals that at low frequency (10 kHz-100 Hz) the permittivities obey the trend PVC < PVC-DMG-Cu(II) < PVC-DMG-Ni(II) < PVC-DMG-Co(II). The permittivities fall monotonously with the applied frequency. The dielectric loss (tan 8) parameter also falls steadily with the applied frequency. However, PVC-DMG-Co(II) exhibits a comparatively large fall in tan 8 from 2.5 to 0.2 in the frequency range (100 KHz-10 MHz), while... 

Dielectric Characteristics. The dielectric constant frequency data [49, 50] for PMDA-BP, PMDA-BPA and their metal-complexes are presented in Figs. 31 and 32 respectively and suggest the following typical features (1) The dielectric values for PMDA-BP and PMDA-BPA complexes fall between 7-8, which is in... 

Excellent dielectric characteristics at all frequencies and high electrical resistivity have made polyethylene one of the most important insulating materials for wire and cable. 

For the measurement of impedance or capacitance of the MIP material in sensing applications, this material is treated as a capacitor dielectric, which is placed between the electrode and electrolyte pseudo-plates. Any sorption or binding of the analyte disturbs the dielectric characteristics of the interface, which is... 

The chemical and thermal stabilities of PCBs, their nonflammabilities and excellent dielectric characteristics led to their wide use as capacitor and transfer fluids. 

Chapter 10 deals with composite films synthesized by the physical vapor deposition method. These films consist of dielectric matrix containing metal or semiconductor (M/SC) nanoparticles. The film structure is considered and discussed in relation to the mechanism of their formation. Some models of nucleation and growth of M/SC nanoparticles in dielectric matrix are presented. The properties of films including dark and photo-induced conductivity, conductometric sensor properties, dielectric characteristics, and catalytic activity as well as their dependence on film structure are discussed. There is special focus on the physical and chemical effects caused by the interaction of M/SC nanoparticles with the environment and charge transfer between nanoparticles in the matrix. 

The electron transfer in polar media is described by the general theory where the reorganization energy is expressed via dielectric characteristics of the medium. The strong interaction between the terms results in the transition of the adiabatic one over the activation barrier. 

Physical and chemical properties of PVD-produced composite films with M/SC nanoparticles including dark- and photo-induced conductivity, conductometric sensoring properties, dielectric characteristics, and catalytic activity. 

Elucidation of the mechanism of new low-frequency dielectric effects in PVD-prepared films with M nanoparticles by widespread investigations of these effects depending on the nature and concentration of nanoparticles embedded in matrices with different dielectric characteristics. 

The dielectric properties of oligodimethylsiloxanes and their dependence on temperature point to good dielectric characteristics of PMS liquids. Taking into consideration that PMS do not form conductive carbon particles in case of electric breakdown or sparking, it is obvious why they are used as liquid dielectrics in transformers and other electric devices. There is a law in Japan and the USA which forbids the use of nonflammable yet toxic pentachlorodiphenyl and leaves room for oligodimethylsiloxanes. This has stimulated a much more active production of PMS liquids in Japan, Germany and other countries. 

SKTN- C SKTN- D SKTN- E 800-1600 7.0 6.0 other materials with good dielectric characteristics operating in the -60 - 250-300°C temperature range. 

SKTN Ph 90-600 2.5-6 To produce monolithic filling and enveloping compounds with good dielectric characteristics operating in the -70 -250°C temperature range in high humidity. 

Below we give the dielectric characteristics of polymethyldimethylsi-lazane film dried for 24 hours at room temperature (the measurements... 

Dielectrics and sealants. Fligh dielectric characteristics of silicone liquids allow them to be widely used in condensers and other electric and radio equipment, in airplanes and radars. High arc resistance of organosilox-anes is due to the formation of carbon dioxide, a good dielectric, when they disintegrate. 

Silicone rubbers have one more very significant advantage in comparison with rubbers based on organic elastomers, and that is high dielectric characteristics. E.g., rubbers based on silicone elastomers do not conduct electric current even at 250-300 °C, whereas rubbers based on organic elastomers become conductive already at 120-150 °C. Insulating properties of silicone rubbers are preserved even at contact with water. 

These high dielectric characteristics in combination with high heat resistance account for the wide application of silicone elastomers in the production of rubberised wires and cables. At present there are several types of cables manufactured from these materials ... 

The dielectric characteristics of barium titanate ceramics with respect to temperature, electric field strength, frequency and time (ageing) are very dependent on the substitution of minor amounts of other ions for Ba or Ti. 

In Section 2 we showed that the properties of amorphous carbon vary over a wide range. Graphite-like thin films are similar to thoroughly studied carbonaceous materials (glassy carbon and alike) in their electrode behavior. Redox reactions proceed in a quasi-reversible mode on these films [75], On the contrary, no oxidation or reduction current peaks were observed on diamondlike carbon electrodes in Ce3+/ 41, Fe(CN)63 4. and quinone/hydroquinone redox systems the measured current did not exceed the background current (see below, Section 6.5). We conventionally took the rather wide-gap DLC as a model material of the intercrystallite boundaries in the polycrystalline diamond. Note that the intercrystallite boundaries cannot consist of the conducting graphite-like carbon because undoped polycrystalline diamond films possess excellent dielectric characteristics. 

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