Two-Phase Solid Electrolytes

Solid electrolytes Zr(R)02 xc possess the maximum ionic conductivity corresponding to the lowest boundary of the solid solution of the fluorite type atx = (0.16 - 

If X 0.16, the solid solution dissociates on two phases with a following sharp decrease of its electroconductivity. It was shown [33] that the correlation between the change in the phase composition and the decrease of electroconductivity in time does exist for the zirconia-based electrolytes. 

In contrast from the single-phase electrolytes, the two-phase electrolytes are characterized by the deeper aging, and the duration of aging is usually much longer. The absence of equilibrium was reported for the zirconia-based electrolytes held at the temperature of 1100°C for 2000-3000 hours [13], for the Z1O2-SC2O3 electrolyte part of the aging curve has the 5-shape form [34], 

FIGURE 1.6 Conductivities of YSZ solid electrolytes at 1000°C versus yttria content ( ) before annealing and ( ) after 30 days of annealing. (Reprinted from Zhuiykov, S., Development of dual sulphur oxides and oxygen solid state sensor for in-situ measurements. Fuel 79 (2000) 1255-1265, with permission from Elsevier Science.) 

4 AN ELECTRON MODEL OF SOLID OXYGEN-IONIC ELECTROLYTES USED IN CAS SENSORS 

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