Abstract
A model based on defect chemistry has been developed to describe the creep behavior of La
0.2Sr
0.8Fe
0.8Cr
0.2O
3−
δ
. The model is based on partial clustering of divalent B site cations and oxygen vacancies. According to the model, the increased strain rates at low
p
O
2
are due to increased mobility of B site cations in linked clusters. The cluster concentration is proportional to the oxygen partial pressure,
p
O
2
m
with
m=−1/2 in accordance with the creep data. The model describes the creep behavior in the entire
p
O
2
range used in the measurements. Models based on random non-interacting defects or including ambipolar diffusion, strontium segregation or partial decomposition cannot give the observed
p
O
2
dependence of the creep behavior.