Phase Formation of Titanium Oxide in Vacuum Condensates Produced by Laser Evaporation

Abstract

Vacuum condensates of titanium oxide are obtained by laser evaporation in vacuum involving vapor condensation onto polycrystalline molybdenum substrates heated between 200 and 1500 ºC. The phase formation in titanium oxide vacuum condensates and their microstructure are studied with x-ray and electron diffraction and transmission electron microscopy. It is established that the formation of titanium oxide vacuum condensates is determined by substrate temperature (Ts): amorphous TiO₂ forms at Ts < 400 ºC, anatase crystallizes at higher Ts and coexists with rutile at Ts = 700–900 ºC, and only rutile is observed at Ts > > 900 ºC. Laser evaporation at Ts < 1400 ºC promotes oxygen-rich TiO₂ phases and that at Ts ≥ 1400 ºC leads to Magnelli phases in titanium oxide vacuum condensates. Higher Ts results in phases in which the titanium–oxygen atomic ratio does not correspond to the TiO₂ formula. It is shown that variations in the substrate temperature and size of crystallites in titanium oxide vacuum condensates are symbate.