The ability for oxygen vacancy generation as a function of temperature and oxygen activity can be determined from both global solutions. It is worth noting again that the B site cation can be easily driven to 3+ for the perovskites which possess high values of AOG or KVO··, such as (La,Sr)FeO3–δ. For instance, δ ∼ 0.2 takes place at ∼1500°C for La0.60Sr0.40FeO3–δ in air, which indicates that all of the Fe ions are in the 3+ valence state. If the temperature is lowered to 1000°C, the oxygen activity has to be lowered to ∼ 10−14 atm to observe this state. Activation energy values for AOG or KVO·· of manganites and chromites are larger than those of ferrites, hence, it is expected that Cr and Mn cations can be reduced to 3+ in air only if the temperature is sufficiently high.