Single-crystal micro/nanostructures and thin films of lamellar molybdenum oxide by solid-state pyrolysis of organometallic derivatives of a cyclotriphosphazene

The solid-state pyrolysis of organometallic derivatives of a cyclotriphosphazene is demonstrated to be a new, simple and versatile solid-state templating method for obtaining single-crystal micro- and nanocrystals of transition and valve metal oxides. The technique, when applied to Mo-containing organometallics N₃P₃[OC₆H₄CH₂CN·Mo(CO)₅]₆ and N₃P₃[OC₆H₄CH₂CN·Mo(CO)₄ py]₆, results in stand-alone and surface-deposited lamellar MoO₃ single crystals, as determined by electron and atomic force microscopies and X-ray diffraction. The size and morphology of the resulting crystals can be tuned by the composition of the precursor. X-ray photoelectron and infrared spectroscopies indicate that the deposition of highly lamellar MoO₃ directly on an oxidized (400 nm SiO₂) surface or (100) single-crystal silicon surfaces yields a layered uniphasic single-crystal film formed by cluster diffusion on the surface during pyrolysis of the metal-carbonyl derivatives. For MoO₃ in its layered form, this provides a new route to an important intercalation material for high energy density battery materials.