Atomic structure of defects and interfaces in TiO2-B and Ca:TiO2-B (CaTi5O11) films grown on SrTiO3

The bronze polymorph of titanium dioxide, TiO2-B, characterized by a crystal structure with a relatively open layered geometry, is a material of interest for various energy applications, including photovoltaics, catalysts, and high-rate energy storage devices. The related phase, CaTi5O11, which serves as an effective template layer, when deposited on (100) SrTiO3, for the growth of high quality single crystalline films of TiO2-B, is also of interest for such applications. For both materials, a detailed understanding of the film growth and defect structure is deemed critical to the successful realization of these applications in thin film devices. Thus, using results obtained with aberration-corrected transmission electron microscopy, we present an analysis of the defects and interfacial structure in CaTi5O11 films grown on (100) and (110) SrTiO3 substrates, as well as in the TiO2-B film grown on (001) CaTi5O11.