An easy sol–gel route for deposition of oriented Ln 2Ti 2O 7 (Ln=La, Nd) films on SrTiO 3 substrates

Abstract

The effect of the orientation of SrTiO 3 (STO) substrates, (1 0 0) or (1 1 0), on the growth of La 2Ti 2O 7 (LTO) and Nd 2Ti 2O 7 (NTO) thin films was investigated. The films were deposited via a sol–gel process coupled to the spin-coating technique. Depending on the substrate orientation, a similar effect was observed on the structural properties for both the LTO and NTO thin films. For (1 1 0)-oriented STO substrate, the films are preferentially (0 0 1) oriented while for (1 0 0)-oriented STO substrates, the orientation is mainly (0 1 2). Those matching appear to be in good agreement with the compatibility between the film/substrate crystal lattices, in relation with the existence of perovskite slabs in Ln 2Ti 2O 7 (Ln=rare earth) compounds. In these latter, a slight disorientation of the (0 1 2) planes with respect to the surface of the substrate was measured. This tilting is even more marked in the case of NTO. The surface morphology was studied by atomic force microscopy.