Gas‐Sensing Properties of Spinodally Decomposed (Ti,Sn)O ₂ Thin Films

The gas‐sensing properties of spinodally decomposed (Ti,Sn)O ₂ thin films on sapphire substrates were investigated for CO, C ₃ H ₈ , and C ₂ H ₅ OH, and hydrogen gases at a temperature of 500°C. The variation in the d ‐spacing of the (101) plane of (Ti _0.5 Sn _0.5 )O ₂ films showed behavior that was typical of spinodal decomposition during annealing at a temperature of 900°C. Transmission electron micrographs of the spinodally decomposed (Ti,Sn)O ₂ films on sapphire (0112) substrates revealed the characteristic modulated structure. The modulated lamella microstructure consisted of TiO ₂ ‐ and SnO ₂ ‐rich regions at intervals of ∼10 nm. The films were very sensitive to hydrogen gas and revealed anisotropic electrical conduction that was influenced by the modulated microstructure, which is characteristic of spinodal decomposition.