Zirconium oxide calcium-stabilized

In all of the discussion of this chapter we have used an aqueous solution as the electrolyte, and electrodes suitable to those aqueous solutions. However, cells are not limited to aqueous solutions. Indeed, other solvents have been used for which liquid ammonia would be an example. Molten salts, such as mixtures of lithium chloride and potassium chloride, have been used for the study of cells at high temperatures. Some studies have been made at higher temperatures, in which solid electrolytes were used. Electrodes compatible with such solvents have also been devised. For example, a zirconium-zirconium oxide electrode stabilized with calcium oxide was used to measure the oxygen potential in nonstoichiometric metal oxides. However, no matter what the electrolytes or the electrodes are, the principles discussed in this chapter such as reversibility and proper measurement must be followed. 

The outlook is different for the direct electrochemical determination of oxygen in the copper melt using a zirconium oxide sensor stabilized with calcium oxide (57)(80)(81)(85). This method is used to an ever-increasing extent. 

Single oxide ceramics, e.g. aluminium oxide (AI2O3, alumina) and zirconium dioxide (Zr02, zirconia), are bioceramics of an inert nature. An inert ceramic does not form a bonding to bone similar to those bioceramics of bioactive nature. Alumina bioceramics are in the pure aluminium oxide form, whereas zirconia bioceramics are partially stabilized by additional oxides, e.g. yttrium oxide, calcium oxide or magnesium oxide. 

Zirconium dioxide, zirconia, is the only oxide of zirconium stable chemically at temperatures below 2000 K. At higher temperatures some dissociation into ZrO and oxygen takes place. The phases of ZrOj, their densities, and phase-transition temperatures are listed in Table 7.5. Zirconia stabilized in the high-temperature cubic phase by addition of 3 to S percent calcium oxide is used as a refractory at temperatures up to 2200° C. ZrOj has been used to dilute UOj in fuel elements. 

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