Nanostructure and Impedance Spectroscopy of Pr0.7Sr0.3Mn1-xMxO3 (M = Fe, Co, Ni; x = 0 and 0.2) Thin Films Grown by Pulsed Laser Deposition

Abstract

Polycrystalline samples of Pr0.7Sr0.3MnO3 and Pr0.7Sr0.3Mn0.8M0.2O3 (M = Fe, Co, Ni), prepared by the citrate- gel process at 950 ºC, have been deposited on yttria-stabilized zirconia (YSZ) single crystal substrates at 700 ºC by pulsed laser deposition (PLD) for application to thin film solid oxide fuel cell cathodes. The structure of the polycrystalline pow- ders prior to deposition was analyzed by X-ray powder diffraction (XRD) data. The XRD patterns were indexed having a single phase orthorhombic perovskite structure (Pbnm). The structure and composition of the films deposited by PLD were analyzed by X-ray Diffraction (XRD), X-ray fluores- cence (XRF) and Scanning Electron Microscopy (SEM). All films are polycrystalline, maintaining the initial orthorhom- bic perovskite structure with a marked texture. The surfaces present pyramidal grains with different size distribution, showing a mean particle size of 80 nm. Electrochemical Impedance Spectroscopy (EIS) measurements were carried out on test cells of these materials. The Pr0.7Sr0.3MnO3 thin film presents an Area Specific Resistance (ASR) value of 25.63 ·cm2 at 850 ºC while Fe, Co and Ni doped materials show resistances of 6.49, 2.42 and 5.12 ·cm2, respectively.