Activation energy for conductivity

Fig. 1. Properties of chromia-alumina catalysts O, activity for conversion of heptane to toluene X, activity for conversion of methylcyclohexane to toluene , activation energy for conduction activation energy for heptane conversion.

A number of studies have also shown that the ionic conductivity of stabilized zirconia depends on the size of acceptors the conductivity tends to be highest with a minimization of the conductivity activation energy for those acceptors whose ionic radius closely matches that of host cation... 

Figure 14.20 Concentration dependences of the conductivity (log a) at BOOK and of the conductivity activation energy for Cai RxFz+x solid solutions. R - La(1), Gd(2), Lu(3). (Reprinted with permission from [63] Copyright (2006) Pleiades Publishing Inc.)...

Table 3 summarizes some of the present state-of-the-art parameters obtained for undoped and doped i -SiH(F) material thus produced. The device-quahty material exhibits semiconductivity because In G vs 10 /Texhibits a straight line with a conductivity activation energy of eV, which is... 

The low DOS achieved in i -Si H enables it to be readily doped, a prerequisite for any device appHcation n- and -type doping is achieved by the addition of PH and B2H to SiH in the gas phase, respectively. Figure 3, a plot of and conductivity activation energy, AH, as a function of PH and 2 6 content, shows that the most heavily f -type doping results in (Hem). By manipulating the plasma (using SiF and H2) or heavily diluting... 

Semiconducting Properties. Sihcon carbide is a semiconductor it has a conductivity between that of metals and insulators or dielectrics (4,13,46,47). Because of the thermal stabiUty of its electronic stmcture, sihcon carbide has been studied for uses at high (>500° C) temperature. The Hall mobihty in sihcon carbide is a function of polytype (48,49), temperature (41,42,45—50), impurity, and concentration (49). In n-ty e crystals, activation energy for ioniza tion of nitrogen impurity varies with polytype (50,51). 

Therefore, the temperature dependence of the conductivity of complexes (LiX)o, igy/MEEP (X=CF3C00, SCN, SO3CF3, BF4) were also compared. The highest conductivity was obtained with BF4, and the activation energies for ion transport were found to be similar, suggesting that the mechanism for ion motion is independent on the salt. The lithium transport number, which varies from 0.3 to 0.6, depending on the complexed salt, does not change with concentration. 

As the working temperature of the substrate was increased, the induction period (the delay time) of increased conductivity decreased due to increased rate of lateral diffusion of hydrogen atoms towards the sensor. The activation energy for surface migration of particles along a Si02 substrate estimated from the tilt of the Arrhenius plot was found to be about 20 kj/mol. 

The temperature dependence of the conductivity can be described by the classical Arrhenius equation a = a"cxp(-E7RT), where E is the activation energy for the conduction process. According to the Arrhenius equation the lna versus 1/T plot should be linear. However, in numerous ionic liquids a non-linearity of the Arrhenius plot has been reported in such a case the temperature dependence of the conductivity can be expressed by the Vogel-Tammann-Fuller (VTF) relationship a = a°cxp -B/(T-T0), ... 

The activation energy for ionic conductivity is derived from a plot of ... 

Estimate the activation energy for ionic conductivity in the Lu2Ti207 phase illustrated in Figure 6.5b. 

The values of the conductivity due to Na+ ions in a glass are given in the following table, (a) Estimate the activation energy for conductivity. The conductivity at 700 K is 0.00316 S m-1. (b) Estimate the value of the diffusion coefficient Da at this temperature if the concentration of Na+ ions is 7.2 x 1027 m-3. (c) Using the data in Chapter 5, Question 5, calculate the Haven ratio at this temperature. 

Figure 1.37 and Figure 1.38 show comparisons of conductivity and activation energy for Sm0 2Ce080,9 and Gdo Cc0y() y5 prepared with different processes. 

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