Origin of Ionic Conductivity

In this consideration, the main characteristic of the solvent is viscosity, q. The ions can move while under the inhuence of an electric held, EU (in V m ), and a steady velocity of the ion, O , is established due to the balance between the electric held force (lz l eE) and the frictional force (6nj rp). If the forces are balanced, then [1] 

George Gabriel Stokes (1819-1903) was a scientist and politician bom in Ireland. He made seminal contributions to fluid dynamics and mathematical physics including the well-known Navier-Stokes equation describing the motion of fluid substances. 

The ion s velocity divided by the electric field represents an important characteristic of the ion that is named mobility, M , and can easily be derived from Equation 3.1 as follows  

Note that the electric field and the ion velocity are vectors while the ion mobility is a scalar quantity with unit m (V s) . However, traditionally in most of the studies, the mobility is reported with the unit of cm (V s). Note that Equation 3.2 is not a fundamental law but represents an idealized model where a sphere with a fixed radius moving in a medium with macroscopic viscosity and, therefore, the applicability of Equation 3.2 for real solutions is quite limited. 

The electrolyte conductivity, k, is the ability of an ion conductive material, liquid or solid, to sustain the passage of electric current. Conductivity depends on the mobility, M , of the electrolyte ions, their charges, Z , and their number densities n (in m 2). If an electrolyte consists of a cation and an anion and their mobilities, charges, and number densities are, respectively, u+ and u, z+ and z, and n+ and n, then k can be given as follows  

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While certain preliminary ideas about the origin of ionic conduction in crystalline solids were derived from the crystal structure investigations of a-AgI by Stiock, and relate to a molten sublattice, i.e., no distinction can be made between a regular Ag lattice site and an Ag on an interstitial site, our knowledge of point defects is based maiidy on the woik of Frenkel, Wagner and Schotlky, Schotlky, and lost, and was developed primarily by studying electrical and optical properties. 

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