Strain relaxation and spinodal decomposition in composition adjusted TiO2-VO2 films on TiO2(100) substrates

In this study, we investigate the process of strain relaxation and spinodal decomposition in TiO2-VO2 films on TiO2(100) substrates. Herein, the film composition was adjusted to Ti0.2V0.8O2 for the relaxation of the in-plane tensile c-axis strain in the films. A 115 nm thick Ti0.2V0.8O2 solid-solution film is epitaxially grown on a rutile -type TiO2(100) substrate using a pulsed laser deposition technique, and is annealed inside the spinodal region. Reciprocal space mapping measurements show that the in-plane tensile c-axis strain is almost fully relaxed in the solid-solution film. Scanning transmission electron microscopy (STEM) observation results reveal that the annealed film causes spinodal decomposition along the c-axis direction, forming vertically aligned multilayer structures. The STEM observations also suggest the presence of interfacial misfit dislocations along the c-axis, indicating the generation of plastic strain relaxation along the c-axis in the film. Composition analysis reveals that the Ti-V interdiffusion between the film and substrate is considerably suppressed. The overall results of this study show that the composition adjustment to Ti0.2V0.8O2 is effective for strain relaxation along the in-plane c -axis and occurrence of spinodal decomposition with reduced Ti-V interdiffusion in the TiO2-VO2 films on TiO2(100). Our study helps establish a method for the formation of nanostructures via spinodal decomposition in the TiO2-VO2 films.

Automated summary

In this study, the process of strain relaxation and spinodal decomposition in TiO2-VO2 films on TiO2 substrates was investigated. It was found that adjusting the film composition can achieve strain relaxation and the formation of multilayer structures after annealing. The film shows plastic strain relaxation along the c-axis with suppressed Ti-V interdiffusion.