Abstract
In this study, the compressive creep behavior of La
0.2Sr
0.8Fe
0.8Cr
0.2O
3−
δ
(LSFCO) in oxygen-controlled atmosphere is investigated in order to understand the underlying stress-induced cation diffusion and defect chemistry in this compound. The creep behavior is investigated in the stress, temperature and grain size ranges of 10–80 MPa, 1100–1175 °C and 3.2–28.5 μm, respectively. The oxygen atmosphere is controlled in the oxygen partial pressure range of
P
O
2
=0.21–10
−14 atm. The material exhibits two markedly different behaviors at high and low
P
O
2
. At high
P
O
2
, the behavior is characterized by the oxygen partial pressure exponent of
m=0.04, followed by a drastic increase in strain rates at low
P
O
2
, characterized by
m=−0.5. In the
m=−0.5 regime, the effect of oxygen partial pressure on the grain size exponent, as well as the transition to power-law creep is investigated. It is concluded that the mechanism responsible for the rapid increase in strain rates increases the contribution of bulk diffusion from predominant (
p=2.3) to nearly pure bulk diffusion (
m=2.07). The same mechanism also increases the stress range for predominant diffusion creep relative to power-law creep.