Innovative sintering process for fabrication of thermochromic smooth VO2 ceramics

Non-equilibrium Spark Plasma Reactive Doping Enables Highly Adjustable Metal-to-Insulator Transitions and Improved Mechanical Stability for VO2

“…It can be seen that the as-synthesized polycrystalline doped VO 2 ceramic pellets via the spark plasma-assisted sintering process exhibit relatively densified morphology, despite the presence of a small number of pores, as indicated in Figure S7. The as-observed morphology is in consistency with the previous reports on polycrystalline VO 2 bulk pellets without doping as synthesized by solid-state reaction or spark plasma sintering. , This indicates that the as-proposed SPARS strategy can effectively achieve the reactive sintering process that sinters the precursor powders into densified bulk pellet within a largely shortened reaction period of 10 min. As their ρ– T tendencies shown in Figure a, the T MIT is more broadly adjusted within 240–350 K. In Figure b, the as-achieved T MIT was plotted as a function of the substitution concentration and further compared with the previous reports. ,,− Similar to the previous reports for doped VO 2 samples, herein substituting the vanadium with elements at higher valence states ( e.g.…”

“…S7. The as-observed morphology is in consistency with the previous reports on polycrystalline VO 2 bulk pellets without doping as synthesized by solid-state reaction or spark plasma sintering 34,35 . This indicates that the as-proposed SPARS strategy can effectively achieve the reactive sintering process that sinters the precursor powders into densified bulk pellet within largely shortened reaction period of 10 minutes.…”

“…The as-observed morphology is in consistency with the previous reports on polycrystalline VO 2 bulk pellets without doping as synthesized by solid-state reaction or spark plasma sintering. 34,35 This indicates that the as-proposed SPARS strategy can effectively achieve the reactive sintering process that sinters the precursor powders into densified bulk pellet within a largely shortened reaction period of 10 min. As their ρ−T tendencies shown in Figure 2a, the T MIT is more broadly adjusted within 240−350 K. In Figure 2b, the as-achieved T MIT was plotted as a function of the substitution concentration and further compared with the previous reports.…”

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

“…Their optical simulations show that higher T lum and ΔT sol can be achieved when using thermochromic nanoparticles [18]. In order for the nanoparticles to achieve the increase in both parameters the following key requirements need to be met: particle sizes far below visible light wavelength (≤100 nm) to avoid scattering of visible light, particles randomly dispersed in the film or coating, and high purity and crystallinity of particles to ensure good switching performance [20,23]. Therefore, high quality thermochromic nanoparticles with a switching temperature suited for application in smart windows (15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25) • C [7,24]) are of great interest.…”

“…In order for the nanoparticles to achieve the increase in both parameters the following key requirements need to be met: particle sizes far below visible light wavelength (≤100 nm) to avoid scattering of visible light, particles randomly dispersed in the film or coating, and high purity and crystallinity of particles to ensure good switching performance [20,23]. Therefore, high quality thermochromic nanoparticles with a switching temperature suited for application in smart windows (15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25) • C [7,24]) are of great interest. The suitable temperature can be achieved through oxygen vacancies (point defects), doping with different elements and strain in the crystal lattice [25,26].…”