Ohmic conductivity

In this procedure, the derivation of s denoted as "deriv (2) is used in order to obtain narrow and sharp peaks and to eliminate conductivity effects due to the independence of e from ohmic conductivity ... 

Swann (Ref 3) traced the mathematical consequences on the assumption that an electret consists of a) a distribution of polarization which decays with time and b) a distribution of surface volume chge which disappears accdg to ohmic conductivity having no relation to the decay of polarization Refs 1) Hackh s Dict(1944), 296-L 2) F. 

Transient Photoconductivity. A solution of neutral molecules in a polar solvent shows only ohmic conductivity, but if ions are formed by the action of the photolytic flash these charge carriers generate an additional current which is proportional to the ion concentration. The observation of such transient photocurrents is the most direct experimental evidence for the formation of free, solvated ions in electron transfer reactions. The quantum yield of ion formation can be obtained through proper calibration procedures and the kinetics of ion recombination can be determined. Figure 7.37 gives an example of such transient photocurrent rise and decay. 

Eq. (3.32) is similar to Eq. (3.27). The values of 0a and 0d are different but they are both constants independent of injection level. The voltage at which ohmic conduction changes to SCLC conduction is given by,... 

It was supposed, that each of the phases is characterized by two parameters the ohmic conductivity <7o(r) and the Hall factor p(r). However each of properties CTo(r) and p(r) from the conductivity tensor (285) admit of only two values Co = cii and p [5, in the first phase, cto = ct2 and p = p2 in the second phase. The essence of ideas described in [118,119] consists in linear transformations from the old fields (j,E) to new fields (j,E ) such that the macroscopic properties of the new system are equivalent to those of the original system. These transformations can be applied only to a two-dimensional system, since they do not then change the laws governing a direct current ... 

Reference 70 provides the first quantitative test of the random resistor network model. In Ref. 121 the authors employed the random resistor network model to determine the behavior of the low-field Hall effect in a 3D metal-nonmetal composite near the percolation threshold. For the following power laws of effective values of ohmic conductivity a, Hall coefficient R, and Hall conductivity a 12, Bergman et al. 121 have obtained the critical exponents ... 

The probability Y(p) of connecting set formation was calculated as a ratio of connecting set number to the number of all possible configurations. The Probability function Y(p) for a three-dimensional rectangular lattice d = 3, 1 = 2 was calculated by a method similar to that of Ref. 62 and Y(p) of Eq. (243). Each Mi bond from the fractal random set Yl/ifp) possesses Hall properties (a, fik) namely ohmic conductivity and a Hall parameter. 

Since p12 = RH, from Eq.(322) it follows that the ohmic resistivity Prf 2- Hence the existence of a field dependence is manifested by a difference between the Hall coefficients (R — R2) of the respective components. If this difference is not equal to zero (R / R2), in a given composite rotational Hall currents exist. These currents yield the contribution to the ohmic resistivity (and to the ohmic conductivity, respectively), which depends on the magnetic field II. Hence, if there are even small inhomogeneities in the substance, then saturation (pu p,Xj, // > 00) does not appear for ohmic... 

As noted above, Eq. (14.17) is only valid for an ideal dielectric. In reality, the charges are never totally in phase for two reasons (I) the dissipation of energy due to the inertia of the moving species and (2) the long-range hopping of charged species, i.e., ohmic conduction. The total current is thus the vectorial sum of /chg and or... 

The bulk ohmic conductivity a of a sample of thickness L, with parallel electrodes of area A is... 

The conduction of electrons through single molecules is however in all known cases not an Ohmic conductivity, but rather a tunneling process. Molecular wires facilitate an electron transport relative to the vacuum, but they differ from metallic wires in terms of the order of magnitude as well as the mechanism of the conductivity. 

The current at any time is usually linearly related to the applied field ("ohmic conduction") for values of the field that arc low in comparison to that which might be employed in use of the material as electrical insulation. 

In the limit of small fields, sinh[eEd/(2kT)]f eEd/(2kT) and normal ohmic conductivity is observed, with j proportional to E. As the temperature rises the conductivity a =j/E falls rapidly. The exponential factor... 

The exponent n is dose to 0.5 for pure polypropylene and points to diffusive carrier transport. For the composites, n changes from about 0.5 at the low frequencies to 1 at the high frequencies. This fact proves the existence of diffusive as well as hopping carrier transport. In the lowest frequency range the compiosite samples show the frequency-independent behavior pointing to the ohmic conduction. This property makes them to be better antistatic material than pure propylene. 

Fig.l. Non-ohmic conductivity a(E)-CT(E->0)/a(E->0) versus logarithm of electric field (E) at various temperatures for (a) (TMTSF)2N03 and (b) (TMTSF)2PFg. 

Fig.3. Non-ohmic conductivity for two samples of (TMTSF)2N03 at 1.5K with different resistivity ratio (rr). Open and close circles for rr-170 and 60, respectively. 

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