The permeation of O in Sr4Fe6-xCoxO13 was studied for x-values ranging from 0 to 1.8 (tables 2 and 3). Samples with x greater than 1.5 consisted of the perovskite phase, SrFe1-xCoxO3, plus the spinel phase, Co3-xFexO4; in addition to the Sr4Fe6O13-type intergrowth phase. The total conductivity and the O-flux increased with increasing x-value. Although the O flux in undoped Sr4Fe6O13 remained constant, that in samples with x greater than 1.5 decreased upon cycling the permeation measurements. The decrease in O flux upon cycling was attributed to O loss and to changes in phase composition at low O partial pressures; as indicated by thermogravimetric analysis.

Oxygen Permeation Studies of Sr4(Fe,Co)6O13. T.Armstrong, S.Guggilla, A.Manthiram: Materials Research Bulletin, 1999, 34[6], 837-44

 

Table 2

Conductivity of Sr4Fe6-xCoxO13 at 900C

 

x

Conductivity (S/cm)

0

0.65

0.6

2

1.2

8

1.5

10

1.8

17

 

 

Table 3

Permeation of O in Sr4Fe6-xCoxO13 at 900C

 

x

O Flux (mol/cm2s)

0

4.0 x 10-10

1.2

1.0 x 10-9

1.5

1.4 x 10-9

1.8

6.0 x 10-9