Hydrothermal treatment with VO2(B) nanobelts for synthesis of VO2(A) and W doped VO2(M) nanobelts.

In this paper, the conversion of VO₂(B) nanobelts under the hydrothermal condition in the absence/presence of dopant was studied. The synthetic conditions, such as the reaction temperature, reaction time, quantity of the dopants and kinds of dopants, were briefly discussed to prepare VO₂(A) and W doped VO₂(M) solid solution. It was found that the dopant played a crucial role in controlling VO₂ polymorph, and the results showed that VO₂(A) was obtained in the absence of dopant, whereas W doped VO₂(M) was obtained in the presence of tungstenic acid. The transformation mechanism from VO₂(B) to VO₂(A) and W doped VO₂(M) was discussed in detail. The phase transition temperature ( T_c) of VO₂(A) and W doped VO₂(M) was evaluated by differential scanning calorimetry. It is found that doped atoms can be successfully doped into the crystal lattice of VO₂(M) matrix, and the T_c of W doped VO₂(M) can be reduced by W doping. The optical switching properties were studied by the variable temperature infrared spectra, and it was found that the as obtained VO₂(A) and W doped VO₂(M) had outstanding thermochromic characters and optical switching properties. [ABSTRACT FROM AUTHOR]