文摘
Li1.18Nb0.82Ti0.18O3 thin film, which has LiNbO3-based subcell and resultant superstructure along its c-axis, was prepared on Al2O3 (0001) single-crystal substrate from alkoxide solutions by a sol–gel and a spin-coating process. The high-temperature X-ray diffraction measurement indicated that the coated gel film was crystallized at 500 °C, and the superstructure was formed at 800 °C. Thickness of the prepared film was typically 100 nm, and was synthesized by a one-step coating process. In order to achieve coexistence of preferred orientation with superstructure in a thin film, a two-step heat treatment was found to be an appropriate method. The layer of the superstructure was parallel to Al2O3 (0001) substrate. Some distribution of layer distance was observed by XRD and TEM. However, the degree of preferred orientation for two-step heat-treated film was estimated to be 1.0 by XRD, showing the advantage of the present processing to fabricate preferred-oriented superstructure thin film.