Solid Oxygen-Ionic Electrolytes

The vast majority of the zirconia-based solid electrolytes can be represented by two types of oxide solid solutions Zr02 + MiO or Zr02 + R2O3 (R rare-earth element). These solutions have a centered cubic lattice (fluorite type), and they can appear when the dimensions of the base cation and the substitutive cations R ) are close enough. In general terms, the zirconia-based solid solutions can be expressed as follows  

EIGURE 1.1 Partial phase diagram for ZrOj-YjOj. (From Nowotny, J. et al., Charge transfer at oxygen/zirconia interface at elevated temperatures. Part 1 Basic properties and terms, Adv. Appl. Ceramics 104 (2005) 147-153. With permission.) 

---

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

FIGURE 1.9 Nanoscaled SEM images of (a) YSZ electrolyte and (b) E t electrode. (From Zhuiykov, S., Electron model of solid oxygen-ionic electrolytes used in gas sensors, Int. J. Applied Ceramic Techn. 3 (2006) 401-411. With permission.)... 

Therefore, even small traces of technological admixtures in the solid oxygen-ionic electrolytes (for example, iron, vanadium, and titanium), which usually accumulate on the grain boundaries, can substantially influence the limits of the practical applicabiUty of electrolytes by temperature and by the level of partial pressure. 

Zhuiykov, S., Electron model of solid oxygen-ionic electrolytes used in gas sensors, Int. J. Applied Ceramic Techn. 3 (2006) 401 11. 

Figure 23. Proton conductivities of Y-doped BaZrtV65 and BaCeCV66 in comparison with the ion conductivity of the relevant solid oxygen ion electrolytes. Reprinted from K.D. Kreuer, St. Adams, W. Munch, A. Fuchs, U. Klock, and J. Maier, Solid State Ionics, 155 (2001) 295-306. Copyright 2001 with permission from Elsevier.

E.C. Subbarao, and H.S. Maiti, Solid electrolytes with oxygen ion conduction, Solid State Ionics 11, 317-338 (1984). 

FIGURE 1.1 Oxygen ionic conductivity of various solid-state electrolytes. (Data from Kharton, V.V. et al., Solid State Ionics, 174, 135, 2004.)... 

Over a large range partial pressures of oxygen ionic conductivity dominates and the material behaves as a solid electrolyte. Under these conditions there is an equilibrium established between oxygen ion vacancies, interstitial oxygen ions and lattice oxygen. 

BIMEVOX — Figure. Oxygen ionic conductivity of solid oxide electrolytes at atmospheric oxygen pressure. See Ref. [ii] for details... 

Choi, S.M., et ah, Oxygen ion conductivity and cell performance of Lao9BaoiGa jMgj03 5 electrolyte, Solid State Ionics, 131, 221-228 (2000). 

Priovano, C. et al., Characterisation of the electrode-electrolyte BIMEVOX system for oxygen separation. Part 1. In situ synchrotron study, Solid State Ionics, 159, 167-179 (2003). 

J.W. Suitor, D.J. Clark and R.W. Losey, Development of alternative oxygen production source using a zirconia solid electrolyte membrane, in Technical progress report for fiscal years 1987,1988 and 1990. Jet Propulsion Laboratory Internal Document D7790,1990. T.J. Mazanec, T.L. Cable and J.G. Frye, Jr., Electrocatalytic cells for chemical reaction. Solid State Ionics, 53-56 (1992) 111-118. 

B.A. Boukamp, I.C. Vinke, K.J. de Vries and A.J. Burggraaf, Surface oxygen exchange properties of bismuth oxide-based solid electrolytes and electrode materials. Solid State Ionics, 32/33 (1989) 918-923. 

A. Manthiram, J.F. Kuo and J.B. Goodenough, Characterization of oxygen-deficient perovskites as oxide-ion electrolytes. Solid State Ionics, 62 (1992) 225-234. 

This is because the apparent activation energies for the interfacial processes are, in general, higher than those for oxygen ionic transport in solid electrolytes (Yamamoto, 2000). The reduction of the working temperature results in a lower oxygen vacancy concentration with concomitant increase of the role of ionic conductivity of electrode material. 

Figure 9.4 Total conductivity of stabilized zirconia (a) and doped ceria (b) solid electrolytes [34—40], compared to the oxygen ionic conductivity of pyrochlore-type Cd2Zr2O7 5 [41], (Cd,Ca)2Ti2O7 5 [42], (Cd,Ca)2Sn2O7 s [43], and 241707 a [44].

Figure 9.5 Comparison of the oxygen ionic (a) and electronic (p- and n-type) (b) conductivity of selected solid electrolytes and mixed conductors under oxidizing conditions. The partial ionic conductivity of perovskite-type...

Li, F., Tang, Y. and Li, L. (1996) Distribution of oxygen potential in ZrO2-based solid electrolyte and selection of reference electrode of oxygen sensor. Solid State Ionics, 86—88, 1027-31. 

---