Synthesis, characterization, and thermodynamic parameters of vanadium dioxide

A novel process was developed for synthesizing pure thermochromic vanadium dioxide (VO2) by thermal reduction of vanadium pentoxide (V2O5) in ammonia gas. The process of thermal reduction of V2O5 was optimized by both experiments and modeling of thermodynamic parameters. The product VO2 was characterized by means of X-ray diffraction (XRD), X-ray photoelectron spectrometry (XPS), scanning electron microscopy (SEM), thermogravimetric analysis (TG), and differential scanning calorimetry (DSC). The experimental results indicated that pure thermochromic VO2 crystal particles were successfully synthesized. The phase transition temperature of the VO2 is approximately 342.6 K and the enthalpy of phase transition is 44.90 J/g.