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

Abstract

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.