Electric orientation

Finally, ferroelectricity is manifest in asymmetrical crystals producing domains of spontaneous polarization whose polar axis direction can be reversed in an electric field directed opposite the total dipole moment of the lattice. The two (or more) directions can coexist in a crystal as domain structures comprising millions of unit cells which contain the same electric orientation. The symmetry elements are temperature sensitive in ferroelectric materials [27]. At a particular temperature called the Curie Point the values of the piezoelectric coefficients reach particularly high values. Above the Curie Point the crystal transformation is to a less polar form and the ferroelectric nature disappears. 

The dichroic ratio at 3300 cm, which is the center of the NH stretching vibration mode of the polypeptide, increases with time, indicating a good orientation of the solution in a field which is by far lower than those required 30) for the usual electrical orientation of this polypeptide in isotropic state 28). When the external field direction is reversed after the equilibrium of the orientation is reached, the dichroic ratio first decreases almost to unity and then recovers with time (Fig. 2). This implies the presence of large particles having huge dipole moments. 

Electrochemistry is the core science upon which many of these electrically oriented advances of the next few decades will depend for their practical execution (see Fig. 1.15). It underlies electrically powered synthesis, extractions (including fresh from brackish water), machining, stabilization of materials, storage of energy in the form of electricity, efficient conversion to electricity of the remaining fossil fuels, and... 

Calculate the effective moment that a gas dipole of water exhibits in the direction of an external field of 10 V cm when subject to electrical orienting and thermal randomizing forces at 25 °C. The dipole moment of water (Contractor)... 

Fig. 15. The polarizing micrograph (left) and the electron micrograph (right) of electrically oriented films of poly(-y-benzylglutamate)s. Left PBLG cast and dried from a CH2Br2 solution (84 V/cm). Right an equimolar mixture of PBLG and PBDG cast and dried from a CHCI3 solution (180 V/cm), O replica...

Thermally Stimulated Current (TSC) A technique useful in studying the transitions of amorphous, polar polymers with rising temperature. A preheated sample is electrically oriented by applying a strong electric field. 

With the exception of the early work by Kapustin [14], who concentrated on the combined acousto-electric orientational effect in polycrystalline nematics, all basic studies of this phenomena have been done in recent years and have considered mainly ho-meotropically aligned nematics. The subject has been summarized in some reviews [14-18], which also outline potential applications. 

A flow of water towards the cathode is anticipated under electric field application. This flow may be related to electrical orientation of spontaneous ballistic protons that induce AS. 

Tinoco, I. The optical rotation of oriented helices. I Electrical orientation of poly-Tr-benzyFL glutamate in ethylene dichloride. J. Amet. Chem. Soc. 81,1540-1544 (1959). 

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