Conductivity, of solid electrolytes

This relationship makes it possible to calculate the maximum ionic conductivity of solid electrolytes. Assuming that the mobile ions are moving with thermal velocity v without resting and oscillating at any lattice site, this results in a jump frequency... 

Another way of looking at high ionic conductivities of solid electrolytes is to consider the activation enthalpy as illustrated in Fig. 8. Generally, the activation enthalpy is strongly correlated with the room-temperature ionic conductivity the higher the room-temperature ionic conductivity, the lower the activation enthalpy. The straight lines in the Arrhenius... 

Detailed information about the conductivity of solid electrolytes can be found elsewhere.2,3,6 8,10,11 As shown in Fig. 3.1, the temperature dependence of the ionic conductivity o can, in general, be described by the semiempirical equation ... 

Figure 15-8. Electrical conductivity of solid electrolytes (and concentrated H2S04 (aq)) as a function of temperature.

The Agl-type superionic solids are important inorganic materials. Several generalizations on the relationship between the conductivity of solid electrolytes and their structures can be made ... 

The correlation (1.15) plays an important role in the analysis of processes stipulated by the small electron conductivity of solid electrolytes, such as the electrolytic permeability of the solid state or the establishment of the chemical potential profile of the elements of solid electrolytes. 

Apparently, the admixture atoms of the metals with alternative valence, local levels of which are adjacent to the valent zone of electrolytes, bring the greatest contribution into the electron conductivity of solid electrolytes. This fact, in one s turn, increases the density of electrons on these levels simply becanse the eqnilibrium between electrons within the conductivity zone and on the local levels can be expressed by the following law in force ... 

Having discussed in Sections II and III concentration and mobility, which influence the conductivity of solid electrolytes, a compilation of solid ionic conductors will be given in this section. This compilation does not presume to be complete because new solid electrolytes are discovered and developed continuously. In Fig. 4, the conductivities of some of the most important ones are shown as a function of temperaure and reciprocal temperature. The conductivity of liquid sulfuric acid is included for comparison. In the following, several important solid electrolytes will be treated according to the type of mobile ions that cause the ionic conductivity. 

Solid Electrolytes, Fig. 2 Temperature dependence of the conductivity of solid electrolyte with chemical disorder [4]... 

As the ionic conductivity of solid electrolytes is generally much lower than the electronic conductivity of electrode materials, the ionic conductivity of the solid electrolytes may determine the lowest possible operational temperature of SOFCs. Apart from high ionic conductivity, the following properties are required ... 

Early on, the limited conductivity of solid electrolytes required cell operation at around 1000 °C, but more recently thin-electrolyte cells with improved cathodes have allowed a reduction in operating temperature to 650 - 850 °C. Some developers are attempting to push SOFC operating temperatures even lower. Over the past decade, this has allowed the development of compact and high-performance SOFC which utilized relatively low-cost construction materials. 

The first solid electrolyte electrochemical oxygen sensors of the USSR were developed in the institute. Also, for the first time in the USSR, the oxygen permeability of the solid electrolytes with dominant ionic conductivity and negligible electronic conductivity as well as of electronic conductors with small ionic conductivity was investigated (see, for instance, [8,19]). The method for measuring the oxygen permeability was later patented under the name Arzhannikov s method for determination of partial conductivities of solid electrolytes (SU patent 1208501,30.01.86). 

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