Belt-like VO2(M) with a rectangular cross section: A new route to prepare, the phase transition and the optical switching properties

Belt-like VO₂(M) with a rectangular cross section was first synthesized by the irreversible transformation of VO₂(A) at the elevated temperatures under the inert atmosphere to the best of our knowledge. The as-obtained samples were characterized by a combination of techniques including XRD, SEM and TEM. The processes of converting VO₂(A) to VO₂(M) were briefly discussed. The as-obtained VO₂(M) has belt-like morphology with a rectangular cross section with typical lengths up to several tens of micrometers, widths ranging from tens of nanometers to several micrometers, and thicknesses about 60-150 nm. The morphology and size of the VO₂(M) were dependent on that of the precursor VO₂(A). The phase transition properties of VO₂(M) were investigated by DSC, indicating that it exhibited a strong phase transition at 67.9 °C in the heating cycle and 61.1 °C in the cooling cycle. Furthermore, the optical switching property of VO₂(M) was studied by the variable-temperature infrared spectra, and it was found that the as-obtained VO₂(M) could be used as the optical switch.