Electron microscope study of the Ti 4 O 7 phase in an annealed titanium oxide evaporated film

Abstract

Interpretable images of the structure of Ti₄O₇ have been obtained with a high-voltage electron microscope at a resolution of approximately 4·5 Å. The Ti₄O₇ phase including defects was observed to grow quickly in an evaporated film made from TiO_17middot;0 during in situ annealing and oxidation in the electron microscope. The basis for interpretation of the images is first investigated using a computer-simulation technique. Then, it is possible to analyse three different types of defect which occur within the Ti₄O₇ phase, i.e. coherent twin boundaries having (104) composition planes, coherent intergrowth of Ti _n O_2n−1 (n = 5, 6) parallel to the (002) plane of Ti₄O₇ and a new, possibly metastable, type of Ti₅O₉ structure which forms coherent boundaries parallel to the (102) plane of Ti₄O₇.