Nonstoichiometry of Ce0.8Gd0.2 O 1.9 − x

Abstract

Oxygen nonstoichiometry of was gravimetrically measured at temperatures from 700 to 1000°C and oxygen partial pressures between 10−24 and 1 atm. Based on the experimental data, the relationship between log x and log , (where x is the oxygen deficiency and the oxygen partial pressure) is discussed and partial molar enthalpy, ΔH¯O, and entropy, ΔS¯O, of oxygen are calculated. In the region of x ≦ 0.04, x is proportional to the −1/4 power of and ΔH¯O, and ΔS¯O, behave as in an ideal solution, showing that oxygen vacancies are doubly charged and defects in are randomly distributed. Thus, the mass action law is satisfied in the area x ≦ 0.04.