Stability of the polydomain state in epitaxial ferroelectric PbTiO3 films

Phase transitions and domain state transformations in a 250 nm thick PbTiO3/SrTiO3 film with c/a/c/a domain structure were investigated by temperature-dependent x-ray diffraction and Raman spectroscopy. Both techniques provide evidence that the film remains tetragonal up to 650 °C, while the bulk sample becomes cubic at 490 °C. Small anomalies in the width of both Bragg peaks and in Raman modes suggest a subtle structural rearrangement around 500 °C.