Ionic conductivity defined

Different from the critical radius, Mori et al. [89] proposed a concept of effective crystallographic index to maximize the oxide ionic conductivity of doped ceria. The index, I, is defined as... 

All solid state ionic conduction proceeds by means of hops between well-defined lattice sites. Ions spend most of their time on specific sites where their only movement is that of small oscillations at lattice vibrational frequencies (10 Hz). Occasionally, ions can hop into adjacent... 

There are two times to consider, therefore, in order to characterise ionic conduction. One is the actual time, tj, taken to jump between sites this is of the order of 10 -10 s and is largely independent of the material. The other time is the site residence time, which is the time (on average) between successful hops. The site residence times can vary enormously, from nanoseconds in the good solid electrolytes to geological times in the ionic insulators. Ion hopping rates, cOp, are defined as the inverse of the site residence times, i.e. 

Ionic conductivity, a, is defined in the same way as electronic conductivity a=nZep... 

For the sake of completeness, Figure 4-5 illustrates the more general situation of isothermal, isobaric matter transport in a multiphase system (e.g., Fe/Fe0/Fe304 / 02). A sequence of phases a, (3, y,... is bounded by two reservoirs which contain both neutral components (i) and electronic carriers (el). The boundary conditions imply that the buffered chemical potentials (u,(R)) and the electrochemical potentials (//el(R)) are predetermined in R] and Rr. Depending on the concentrations and mobilities (c/, b), c, 6 ) in the various phases v, metallic conduction, semiconduction, or ionic conduction will prevail. As long as the various phases are thermodynamically stable and no decomposition occurs, the transport equations (including the boundary conditions) are well defined and there is normally a unique solution to the transport problem. 

Ions in a food oscillate transversely under the influence of the microwave electric field, colliding with their neighboring atoms or molecules. These collisions impart molecular motion which is defined as heat. Materials with mobile ions are conductive. The more available ions in a food, the higher the electrical conductivity. Microwave absorption in a food thus increases with its ionic content. The portion of microwave absorption due to ionic conduction can be described as a portion of the dielectric loss factor, ec. Geyer (1990) recently discussed this concept in his publication. 

The oxidation rate depends not only on the gas composition and the temperature parameter, but also on the electric potential difference between the electronically conductive part of the anode electrode and the ionically conductive electrolyte. Defining the electric potential of the solid part of the anode electrode as zero potential, the reaction rate depends on the electric potential in the electrolyte, other hand, the reduction reaction rate depends on the electric potential difference at the cathode electrode, which is the difference between the given cell voltage, Uceii, and the electrolyte potential, equilibrium constants are determined by the... 

Hittorf transport method — Only at infinite dilution can the molar conductivity of a solution be split into the two limiting molar conductivities associated with the individual ions, which are independent of each other. This is because only at infinite dilution can we completely neglect interionic interactions. However, in order to determine the values of the individual ionic conductivities, an additional measurement is necessary in order to partition Ao into AJ and Ag we must determine the so-called -> transport numbers of the individual ions. The total current i, can be written as the sum of partial currents i+ and i, corresponding to the currents carried by the cations and anions. We define the transport number of the cations, t+, as t+ = -fi— = and simi-... 

Ionic mobility — Quantity defined by the velocity of an ion moving in a unit electric field (SI unit m2 V-1 s-1). The ionic mobility of ion i (uf) is related to its molar ionic conductivity (A ) by A = zfFui, where Z is the charge number of the ion. The ionic mobility is also related to the -> diffusion coefficient (A) by the Nernst-Einstein... 

Molar ionic conductivity — This quantity, first introduced by -> Kohlrausch, is defined by A = Zi Fui (SI unit Sm2 mol-1), where Zj and 14 are the charge number and -> ionic mobility of an ion, respectively. The molar -> conductivity of an electrolyte M +X (denoted by A) is given by A = u+X+ + i/ A, where A+ and A are the molar ionic conductivities of the cation and anion. The A value of an ion at infinite dilution (denoted by A°°) is specific to the ion. For alkali metal ions and halide ions, their A values in water decrease in the orders K+ > Na+ > Li+ and Br- > Cl- > F-. These orders are in conflict with those expected from the crystal ionic radii, because the smaller ions are more highly hydrated, so that the -> hydrated ions become larger and thus less mobile. Based on Stokes law, the radius of a hydrated ion... 

Ionic conductivity is defined as the reciprocal of proper resistance ( Rb). It is obtained by calculating... 

---