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

Abstract

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 N 3P 3[OC 6H 4CH 2CN·Mo(CO) 5] 6 and N 3P 3[OC 6H 4CH 2CN·Mo(CO) 4 py] 6, results in stand-alone and surface-deposited lamellar MoO 3 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 MoO 3 directly on an oxidized (400 nm SiO 2) 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 MoO 3 in its layered form, this provides a new route to an important intercalation material for high energy density battery materials.