Titanium fullerenoid oxides

Nanostructured titanium oxide films synthesized by supersonic cluster beam deposition were analyzed by high-resolution transmission electron microscopy. Nanoparticles were produced in a pulsed microplasma cluster source in the presence of He or helium-oxygen mixture as carrier gas. While films grown using He consist only of rutile and anatase TiO2 nanocrystals formed upon exposure to air, films grown with a He/O mixture also contain isolated TiOx cages that closely resemble carbon fullerenes. The diameter of the cages ranges from about 0.9 to 2.7 nm. A fraction of the cages have irregular shapes, possibly induced by oxygen vacancies. The TiOx fullerenoids grow in the gas phase, in a narrow temperature/pressure range within the cluster source, and are preserved through low-energy deposition.