Strontium-doped lanthanum manganite coatings crystallised after air annealing of amorphous co-sputtered films

Strontium-doped lanthanum manganite films were deposited on steel, silicon and yttria stabilised zirconia substrates by reactive co-sputtering of La0.85Sr0.15 and Mn targets in a Ar–O2 gas mixture. In this study, the discharge current applied to the manganese target was varied to adjust the film composition whereas that of the La–Sr target was maintained at a constant value of 1 A. The use of 0.4 A dissipated on the Mn target allowed the formation of a film with the La0.85Sr0.15MnO3 stoichiometric composition. As-deposited films were amorphous and exhibited a dense brittle fracture cross-section. Air annealing for 1 h at 700 °C induced the crystallisation in the expected perovskite structure of the coatings with a (La + Sr)/Mn atomic ratio ranging between 0.87 and 1. This crystallisation came with a strong improvement of the film electrical conductivity at room temperature.