Multi-stoichiometric quasi-two-dimensional W n O 3n-1 tungsten oxides.

Quasi-two-dimensional tungsten oxide structures, which nucleate by epitaxial growth on W19O55 nanowires (NW) and grow as thin platelets, were identified. Both the nanowires and the platelets accommodate oxygen deficiency by the formation of crystallographic shear planes. Stoichiometric phases, W18O53 (WO2.944), W17O50 (WO2.941), W16O47 (WO2.938), W15O44 (WO2.933), W14O41 (WO2.929), W10O29 (WO2.9), and W9O26 (WO2.889), syntactically grow inside a single platelet. These layered crystals show a new kind of polycrystallinity, where crystallographic shear planes accommodate oxygen deficiency and at the same time stabilize this multi-stoichiometric structure.