The impact of bead milling on the thermodynamics and kinetics of the structural phase transition of VO2 particulate materials and their potential for use in thermochromic glazing

Hydrothermal Synthesis of Monoclinic VO2 Microparticles without Use of Hazardous Reagents: A Key Role for the W-Dopant

“…This indicates that multiple species of VO 2 (M) are present in the product with different particle sizes and/ or degree or distribution of doping, which all influence T switch . 9,16 The XRD analyses confirmed that with increasing reaction time, the fraction of VO 2 (M) in the product mixture increases, which corroborates the trend in ΔH switch . At the start of the reaction, VO 2 (A) and VO 2 (B) are formed which can be seen in the diffraction patterns of the product obtained after 2 and 5 h reaction time (Figure 3).…”

“…In addition, multiple peaks, shoulder peaks, tailing, and overlap between the heating and cooling peaks were observed in the DSC analyses of the obtained particles. This indicates that multiple species of VO 2 (M) are present in the product with different particle sizes and/or degree or distribution of doping, which all influence T switch . , …”

“…20 Most hydrothermal reactions to synthesize VO 2 (M) use hydrazine as a reducing agent for the reaction of vanadium pentoxide to a vanadium(IV) complex. 16,21,22 Hydrazine has two benefits: one is its strong reducing character and the other is that it supplies the reaction mixture with ammonia as a side product that can be used for complexation and stabilization of vanadium(IV). Dong et al proposed that the type of vanadium(IV) complex is crucial for the crystallization.…”

“…Hydrothermal synthesis of VO 2 using hydrazine can yield highly crystalline VO 2 (M) nanoparticles with good switching performance and particle size <100 nm, which are suitable for high performance thermochromic coatings and films. 16,21,22 However, the use of hydrazine also presents some disadvantages. Hydrazine leads to oxygen vacancies in the obtained VO 2 nanoparticles.…”

Microwave Hydrothermal Preparation of VO2

“…[ 1 ] It can transform from a monoclinic phase to a tetragonal phase at about 68 °C. [ 2–5 ] The principle of this phase transition is generally reported that outer d electrons can determine the state of VO 2 as the outer d electrons of VO 2 have similar energy with Fermi surface electrons. When the environment changes, such as temperature, pressure, light, or magnetic field, the outer d electrons could be converted to each other under the two states of localization and public ownership.…”