Perovskite-type lanthanum chromium-based oxide films prepared by ultrasonic spray pyrolysis

Ultrasonic spray pyrolysis was used to form 2–8 m thick LaCrO₃ films on different substrates from La(CrO₄)(NO₃)·nH₂O precursor films. There was an optimum substrate temperature for the formation of uniform precursor films by the spray pyrolysis. When the substrate temperature was lower than 250 °C, dry precursor films were not formed, while above 250 °C the deposition rate decreased with substrate temperature. The precursor films were converted to perovskite-type oxide films by heat treatment at 800 °C in a nitrogen atmosphere. Both A-site substituted (La_0.8Ca_0.2) CrO₃ and B-site substituted La(Cr_0.5Mn_0.5)O₃ oxide films were formed in a similar manner. Electronic conductivity of the oxide films was improved by repetitions of the spray pyrolysis and heat treatment in nitrogen.