Structure and microstructure of epitaxial Sr_nFe_nO_3n−1 films

Abstract

Thin films of SrFeO_{3 −  x} (0 ≤ x ≤ 0.5) (SFO) grown on a (LaAlO₃)_0.3 (SrAl_0.5Ta_0.5O₃)_0.7 (LSAT) substrate by pulsed laser deposition have been structurally investigated by electron diffraction and high resolution transmission electron microscopy for different post-deposition oxygen treatments. During the deposition and post-growth oxidation, the oxygen-reduced SFO films accept extra oxygen along the tetrahedral layers to minimize the elastic strain energy. The oxidation process stops at a concentration SFO_2.875 and/or SFO_2.75 because a zero misfit with the LSAT substrate is reached. A possible growth mechanism and phase transition mechanism are suggested. The non-oxidized films exhibit twin boundaries having a local perovskite-type structure with a nominal composition close to SFO₃.

Acknowledgements

This work has been performed within the framework of IUAP V-1 of the Belgian government.