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 La 0.9 Sr 0.1 Cr 1‐ x M x O 3 (M = Mg, Al, Ti, Mn, Fe, Co, Ni; 0 ≤ x ≤ 0.1) perovskites has been studied in oxidizing and reducing atmospheres in the temperature range from 50° to 1000°C. Cobalt doping of La 0.9 Sr 0.1 CrO 3 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 La 0.9 Sr 0.1 Cr 1‐ x M x O 3 perovskites with doping of ≥1 mol% aluminum or 10 mol% cobalt. TECs of La 0.9 Sr 0.1 Cr 0.96 Co 0.02 Al 0.02 O 3 were 10.5 × 10 − 6 /°C in air, 10.7 × 10 −6 /°C under He–H 2 atmosphere (oxygen partial pressure of 4 × 10 − 15 atm at 1000°C), and 11.8 × 10 − 6 /°C in H 2 atmosphere.