In Situ Preparation of VO₂ Films with Controlled Ionized Flux Density in HiPIMS and Their Regulation of Thermal Radiance

Abstract

Vanadium dioxide is a well-known phase-change material on account of its unique changes of optical property, which has seen a great increase in its implementation for the regulation of thermal radiance. However, the fabrication of VO 2 needs strict conditions for its narrow sliver in the phase diagram. In this paper, in situ preparation of VO 2 films by high-power impulse magnetron sputtering is proposed, in which ionized flux density is used to direct the crystal growth. Besides, the surface structure and thermochromic behaviors of the deposited films are studied in detail. Furthermore, simulations are carried out for the sake of optimizing the thickness of VO 2 films with the largest emissivity modulation ability, and the experimental result reveals that their tuning range reaches up to 0.32. It is believed that our work will find wide applications not only in fundamental material science but also in thermal radiance regulation.

Effect of Unit Cell Shape on Switchable Infrared Metamaterial VO 2 Absorbers/Emitters

“…The thermochromic vanadium dioxide (VO 2 ) has been placed on forestage of many reversible materials, due to its discrepant reflection and transmittance of films [ 16 , 33 , 34 ]. The concepts of four switchable infrared metamaterial emitters based on VO 2 are presented in Figures 1(a) –(d).…”

“…However, most of the metamaterial absorbers/emitters are fixed once the structure is fabricated. Of these, the phase-change materials, such as VO 2 and Ge 2 Sb 2 Te 5 (GST) whose permittivity changes dramatically with stimulation [ 16 – 19 ], were introduced to metamaterial absorbers/emitters to obtain the function of manipulating emittance or infrared radiation [ 12 , 20 – 22 ]. Cao et al designed an ultrathin reconfigurable metasurface based on Au / SiO 2 /Ge 2 Sb 2 Te 5 /Au multilayer and realized dynamic control of multispectral thermal emission from 2 to 4 μ m [ 22 ].…”

Smart Materials for Dynamic Thermal Radiation Regulation

“…Contrary to positive differential thermal emissivity, negative differential thermal emissivity of VO 2 means emitting lower radiation at higher temperatures, which can be basically realized by depositing VO 2 film on high emissivity layers like SiO 2 . [ 17,29 ] This property can help maintain the consistency of the MIR signals with the surroundings to realize an infrared dynamic concealment. [ 30 ] Rather than the whole MIR region, emissivity at 3–5 µm and 8–14 µm is the key point in practical application.…”

Size-Controllable M-Phase VO2 Nanocrystals for Flexible Thermochromic Energy-Saving Windows

“…VO 2 -based thermochromic smart windows are mainly divided into rigid and flexible films according to their flexibility. Rigid smart windows are fabricated by depositing VO 2 films on rigid substrates such as glasses. − Flexible smart windows are prepared by casting a mixture of VO 2 nanoparticles with a transparent matrix on a flat surface. Compared with rigid films, flexible films have advantages in cost reduction, versatility, flexibility, and mass preparation. , The T lum and Δ T sol of flexible VO 2 thermochromic films are two key properties determining their practical performance.…”