Mixed-alkali effect

Mix bridging, 15 545 Mixed-alkali effect (MAE), 12 586-587 Mixed bauxites, 2 347 Mixed-bed columns, 14 405, 407 in ion exchange, 14 404 Mixed-bed resins, 14 412 Mixed chalcogenides, 12 359 Mixed formulation fertilizers, 11 123 Mixed-integer linear programming (MILP), 20 748 26 1023... 

Fig. 4.2 Typical variations in ionic conductivity with composition. In all cases, variations in alkali or silver content are very low compared to the observed variation in log a (a) influence of the network modifier (LijS) (b) influence of a doping salt (c) mixed alkali effect (d) mixed anion effect. References for data are indicated in Souquet and Perera (1990).

No simple thermodynamic model is yet able to explain the large decrease in conductivity when partially substituting one alkali metal for another, i.e. the so-called mixed alkali effect. Systematic analysis of the pre-... 

Another widely studied phenomenon in alkali borate glasses is the mixed alkali effect, the nonlinear change in glass properties when a second kind of alkali oxide is added into the single-alkali glass. Models have been suggested to explain the mixed alkali effect (144), but a universally accepted model has not been developed as of this writing. 

Figure 15-7. Mixed alkali effect tracer diffusion coefficients ), and D(a) from electrical conductivity (D(a ) = (R T/c -ia zfF1)) for (Cs Na, N)20 5 Si02, as a function of N, see [R. Tferai (1971)]. T = 480 °C.

R. Kirchheim. Interstitial diffusion in glasses and the mixed alkali effect. In H. Jain and D. Gupta, editors, Diffusion in Amorphous Materials, pages 43-54, Warrendale, PA, 1994. The Minerals, Metals and Materials Society. 

Significant non-idealities can occur in the solids with two kinds of mobile cations (or anions). The so-called mixed alkali effect refers to the partly extremely strong depression of the alkali ion conductivity in crystals or glasses if substituted by another alkali ion. This is explained by the individually preferred environments and their interactions.221"228... 

Figure 6.14. Variation of self-diffusion coefficient of LF (x) and (o) ions with mole fraction of potassium. Inset variation of electrical conductivity with mole fraction of potassium. Lines are only indicative of trends. Note the occurrence of the mixed alkali effect in a. (After Balasubramanian and Rao, 1993).

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