VO2 and V2O5 nano- and micro-materials and processes of making and uses of same

A method for making VO2 nano-material or micro-material having an M1 phase structure and oxygen stoichiometry that deviates 2% or less from theoretical stoichiometry,

• wherein the VO2 nano-material or micro-material exhibits a metal-insulator transition and 80% or more of the total change in resistivity resulting from the metal-insulator transition occurs over a range of 5° C. or less, comprising:
• a) providing a solid V3O7.H2O nano-material or micro-material and hydrothermally reducing the solid V3O7.H2O nano-material or micro-material with water and, optionally, one or more agents selected from the group consisting of:
• i) a C1-C8 linear or branched, substituted or unsubstituted, mono- or di-alcohol;
• ii) a C1-C8 linear or branched, substituted or unsubstituted mono- or di-carboxylic acid;
• and
• iii) a C1-C4 linear or branched, substituted or unsubstituted dialkyl-CO to produce a mixture of VO2 (A) and VO2 (B) nano- or micro-material;
• b) filtering and washing the product from a) to isolate the mixture of VO2 (A) and VO2 (B) nano-material or micro-material;
• c) annealing the isolated mixture of VO2 (A) and VO2 (B) nano-material or micro-material under an inert atmosphere at a temperature of at least 450° C.;
• and
• d) cooling the product of c) to produce VO2 nano-material or micro-material in the M1 phase.