Multi-stoichiometric quasi-two-dimensional WnO3n−1 tungsten oxides

Abstract

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 (WO_2.944), W₁₇O₅₀ (WO_2.941), W₁₆O₄₇ (WO_2.938), W₁₅O₄₄ (WO_2.933), W₁₄O₄₁ (WO_2.929), W₁₀O₂₉ (WO_2.9), and W₉O₂₆ (WO_2.889), 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.