Complex impedance analysis on orientation effect of LaMn0.6Al0.4O3 thin films

Preferred (100)-oriented and complete (100)-oriented LaMn 0.6 Al 0.4 O 3 thin films were deposited on (100)-LaNiO 3 -coated silicon substrates by spin-coating method. Complex impedance spectroscopy was used to provide a convincing evidence for the existence of grain and grain boundary that were separated in the frequency domain in impedance spectrum. It suggests that the better grain orientation is effective in lowering the resistivity and activation energy but with little influenced on grain boundary. The analysis of impedance dependent on frequency, reveals that the relaxation is a thermally activation process. The grain and grain boundary conduction obey the Arrhenius behavior with activation energy 1.2294–1.3273 eV. The mechanism associated with the change of the electrical properties of the thin films is discussed.