Defect thermodynamic properties of pure and doped ceria

2 Defect thermodynamic properties of pure and doped ceria 

The temperature and p02 dependence of x in Ce02 x has been reported in a number of publications. Three comple- 

The partial molar free energy of formation of Ce02 x of a given nonstoichiometry, AGq is  

ASq X show a sigmoidal variation with x in the range -2.8 log X -0.6. Bevan and Kordis concluded that AHq ASq x temperature independent in the temperature range 872-1169°C. The strong X dependence of AHq for x 0.01 indicates that there is strong interaction among defects at these larger departures from stoichiometry. 

Numerous works have attempted to account for the complex thermodynamic dependence of the CeOg.x nonstoichiometry on temperature and oxygen partial pressure. In the late 1960s Kofstad and Hed proposed a model based on singly and doubly ionized Ce interstitials. Blumenthal et al interpreted the defect structure of 

---