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.