TiO₂-SnO₂ deposits prepared by CVD

Deposits in the system of TiO₂-SnO₂ were prepared at 625°C on fused-quartz or NaCl substrates by CVD using TiCl₄, SnCl₄ and H₂O as sources. The deposits obtained at Sn/(Sn+Ti) of 0-30 at% in the sources, were single phases of TiO₂-SnO₂ solid solutions. Two-phase mixtures of anatase-type and rutile-type phases, were prepared at Sn/ (Sn+Ti) of 40-70 at% in the sources. Rutile-type single phases deposited at 80-100 at% in the sources. Dendritic structure was observed for the deposits of the anatase-type single phases. The deposits of the two phases of anatase-type and rutile-type structures, were dense films. Faceted columnar textures were observed for the deposits of the rutile-type single phase. The transmission electron microscope observation of a two-phase mixture showed that the grains of the rutile-type structure, about 500 nm in size, were contained in the matrix of an anatase-type solid solution. Lattice parameters of the anatase-type solid solutions increased linearly with increasing SnO₂ in the solid solutions. The maximum Sn/ (Sn+Ti) found in the anatase-type solid solutions was 41 at%. In the rutile-type phases, Sn/ (Sn+Ti) was over 96 at%.