Processing and electrical conductivity of non-stoichiometric lanthanum strontium manganite perovskites prepared from powders synthesized by a polymerizable-complexation route

Abstract

Perovskite ceramics with non-stoichiometric compositions given by (La0.85Sr0.15)0.98MnO3-δ ((LS)0.98M-85) and (La0.80Sr0.20)0.98MnO3-δ ((LS)0.98M-80) were obtained by pressureless sintering (1500 °C for 2 h) from powders synthesized by a polymerizable-complexation route and then calcined (500 °C for 1 h). It was found that the two sintered ceramics contain trigonal (i.e., R3̅c) Sr-doped lanthanum manganite as majority phase, and also hexagonal (i.e., P63/m) La(OH)3 in trace amounts in the case of (LS)0.98M-85 and in abundant amounts in the case of (LS)0.98M-80. The (LS)0.98M-85 ceramic is stable and therefore usable, whereas on the contrary the (LS)0.98M-80 ceramic eventually swelled and turned into a powder due to the abundant La(OH)3 that uptakes water from the atmosphere. Finally, it was found that the (LS)0.98M-85 ceramic has appropriate electrical properties for use as cathode in solid oxide fuel cells, with a total conductivity of ~ 145 S/cm at 1000 °C and an activation energy of 0.067(2) eV.