Epitaxial growth of (SrBa)Nb2O6 thin films on SrTiO3 single crystal substrate

(SrBa)Nb2O6 (SBN) thin films with tetragonal tungsten bronze structure were deposited on strontium titanate single crystals by pulsed laser deposition. Epitaxial relations were studied as a function of substrate termination and orientation. On STO(100) surface, SrO termination leads to (001) SBN orientation, whereas TiO2 termination to (310) orientation. A growth model is proposed, explaining the epitaxial relation with the substrate on the basis of the perovskite kernel contained in the unit cell of the tetragonal tungsten bronze structure. The perovskite kernel grows in cube-on-cube relation on the perovskite substrate. The high growth temperature of at least 720 degrees C assures the necessary mobility for the arriving atoms to organize in the SBN structure around the perovskite nuclei. Piezoelectric measurements carried out by atomic force microscopy on individual grains show that it is possible to switch the polarization, thus proving ferroelectric properties. The geometry of the piezoelectric response is compatible with grain orientation as known from diffraction experiments. (c) 2006 American Institute of Physics.