Control of the thermal expansion of strontium-doped lanthanum chromite perovskites by B-site doping for high-temperature solid oxide fuel cell separators

The thermal expansion of La0.9Sr0.1Cr1-xMxO3 (M = Mg, Al, Ti, Mn, Fe, Co, Ni; 0 less than or equal to x less than or equal to 0.1) perovskites has been studied in oxidizing and reducing atmospheres in the temperature range from 50 degrees to 1000 degreesC. Cobalt doping of La0.9Sr0.1CrO3 was an effective way of increasing the average linear thermal expansion coefficient (TEC), whereas titanium doping showed a negative effect, No effect on the TECs was observed for the B-site dopants in perovskites with the remaining dopants, Linear thermal expansion behavior was observed in the La0.9Sr0.1Cr1-xMxO3 perovskites with doping of greater than or equal to1 mol% aluminum or 10 mol% cobalt, TECs of La0.9Sr0.1Cr0.96Co0.02Al0.02O3 were 10.5 x 10(-6)/degreesC in air, 10.7 x 10(-6)/degreesC under He-H-2 atmosphere (oxygen partial pressure of 4 x 10(-15) atm at 1000 degreesC), and 11.8 x 10(-6)/degreesC in H-2 atmosphere.