Orientation-Controlled 400 nm Thick Ferroelectric PbTiO3Films with Low Strain Directly Grown below the Curie Temperature by the Hydrothermal Method

High Resolution Image Download MS PowerPoint Slide Lead titanate (PbTiO 3 ) is a well-known perovskite-type ferroelectric with a large tetragonal distortion. Previous preparation methods of PbTiO 3 films such as the sputtering method and the sol–gel method typically require a temperature higher than the Curie temperature, T C, (490 °C). In this work, 400 nm thick epitaxial PbTiO 3 films are successfully grown on (100), (110), and (111) SrTiO 3 substrates coated with SrRuO 3 layers by the hydrothermal method at 150 °C, which is below T C . X-ray diffraction analysis showed that only (001)-, (101)-, and (111)-oriented domains with small residual strain are obtained even for 400 nm thick films grown on (100) c -, (110) c -, and (111) c -oriented SrRuO 3 //SrTiO 3 substrates, respectively, without 90° domains (i.e., combinations of (100)/(001) and (110)/(101) orientations do not exist). These results suggest that only the domain with a smaller lattice mismatch between the underlying layer and substrate is selectively grown in films up to 400 nm thick to minimize the impact of the elastic energy due to lattice mismatch. This can be understood by the direct growth of the ferroelectric phase on the underlying layers below T C without a phase change together with the low thermal strain due to the low deposition temperature.