Activation energies of conduction

TABLE 8.2 Conductivities, o, Cationic Transport Numbers, Molar Conductivities of the Electrolyte (A) and Cation (X+), and Activation Energies of Conduction, A, for a Number of Melts and Aqueous KCl Solution... 

Table 2. Thermal activation energy of conductivity Ed, edge energy of the electronic absorption spectra Eopl, and optical activation energy of photoconductivity Ea/2 for some polyheterocycle polymers [222]...

There is as yet no satisfactory explanation for the observed dark conductivity. Although attempts have been made to relate the observed activation energy of conductivity given by the equation... 

Activation energies of conduction fall into three groups (86). 

The electrical properties of the pyrolyzed polymer differ in a number of ways from those of polyacrylonitrile. The overall conductivity increases, while the activation energy of conductivity decreases. A rough correlation is found between a0 and E of equation 15 in that a high a0 was associated with a low E (57). Increasing the degree of orientation causes an increase in conductivity but the activation energy remains unaffected. This is typical of electronic conductivity. 

The use of conductivity measurements for structural and polymerization studies has been suggested. Warfield and Petrie (130) found that the magnitude and activation energy of conductivity increased as a function of the degree of polymerization. Conversely, this could be used to determine the degree of polymerization. 

Figure 2. Conductivity data on KTP and KTA, along z, as a function of temperature for determination of the activation energies of conduction. Key KTP Philips flux KTP Airtron high temperature hydrothermal A KTA DuPont flux.

Nickel oxides prepared at 250 and 300° are alsop-type semiconductors (40). This means that, although the oxide surface has been reduced, the oxide phase still contains an excess of oxygen. Electrical conductivities and activation energies of conductivity are identical for NiO(200°) and NiO(250°) (ff2oo° X 10-1 ohm-i cm-i = 24kcal/mole) (41),... 

Catalyst Concentration of foreign ions (at.%) Surface area (m2/gm) Stoichiometric composition (at.%) Concentration of nickel" (at.% Ni) Electrical conductivity at 250° (ohm i cm ) Activation energy of conductivity (kcal/mole)... 

Figure 6.13. Variation of glass transition temperature Tg, conductivity, ojc, at room temperature and activation energy of conductivity, for 0.5[xNa2S - (1-x) Li2S] -0.5 SiS2 (After Pradel and Ribes, 1994).

It would be attractive to correlate the energies of the charge-transfer bands with the electrical conductivities and the activation energies of conduction. A rather close connection of these properties has been demonstrated for Tl3Fe(CN)6 (77), but no obvious correlation could be... 

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