The double-walled nature of TiO2 nanotubes and formation of tube-in-tube structures – a characterization of different tube morphologies - So, Seulgi; Riboni, Francesca; Paul, Dennis; Hammond, John; Tomanec, Ondrej; Zboril, Radek; Sadoway, Donald R.; Schmuki, Patrik (Friedrich-Alexander-Universität Erlangen-Nürnberg, 2017)