Control of the Thermal Expansion of Strontium‐Doped Lanthanum Chromite Perovskites by B‐site Doping for High‐Temperature Solid Oxide Fuel Cell Separators

Abstract

The thermal expansion of La0.9Sr0.1Cr1‐xMxO3(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 La0.9Sr0.1CrO3was 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 ≥1 mol% aluminum or 10 mol% cobalt. TECs of La0.9Sr0.1Cr0.96Co0.02Al0.02O3 were 10.5 × 10−6/°C in air, 10.7 × 10−6/°C under He–H2 atmosphere (oxygen partial pressure of 4 × 10−15 atm at 1000°C), and 11.8 × 10−6/°C in H2 atmosphere.