A Novel Route for the Easy Production of Thermochromic VO₂ Nanoparticles

Abstract

In this work, a simple, fast and dry method for the fabrication of a thermochromic product with a high load of VO 2 (M1) consisting of the controlled heat treatment of pure vanadium nanoparticles in air is presented. After a complete design of experiments, it is concluded that the most direct way to attain the maximum transformation of V into VO 2 (M1) consists of one cycle with a fast heating ramp of 42 °C s À 1 , followed by keeping 700 °C for 530-600 seconds, and a subsequent cooling at 0.05 °C s À 1 . Careful examination of these results lead to a second optimum, even more suitable for industrial production (quicker and less energy-intensive because of its lower temperatures and shorter times), consisting of subjecting V to two consecutive cycles of temperatures and times (625 °C for 5 minutes) with similar preheating (42 °C s À 1 ) but a much faster postcooling ( 8°C s À 1 ). These green reactions only use the power for heating a tube open to atmosphere and a vanadium precursor; without assistance of reactive gases or catalysts, and no special vacuum or pressure requirements. The best products present similar thermochromic properties but higher thermal stability than commercial VO 2 particles. These methods can be combined with VO 2 doping.

Facile Fabrication of High-Performance Thermochromic VO2-Based Films on Si for Application in Phase-Change Devices

“…Such plateau temperatures are maintained for different reaction times ( t r ) to optimize VO 2 yields as well as to achieve full oxidation of the different layer thicknesses addressed (the greater the V-GLAD volumes, the longer the oxidation times). Thereupon, samples are instantaneously cooled in air (for a detailed outline of the fast thermal treatment procedure, refer to our previous works ,, ). All annealed samples are listed in Table together with their treatment conditions and nomenclature.…”

“…The other end side also crosses and is fixed to another piece that is part of a handlebar used to slide the specimen holders inside and outside. In this way, by fixing a temperature in the center of the furnace, one is able to control the temperature increase (heating rate) by moving the boat more and more inside the furnace (for a more detailed overview of the reaction system, refer to previous studies ,, ). Consequently, translation routines were prepared for reaching an average heating rate of 42 °C s –1 , as well as for adjusting longer or shorter reaction times at a desired temperature.…”

Reactivity of Vanadium Nanoparticles with Oxygen and Tungsten

“…In a previous work [4], we demonstrated simple, fast, dry, cheap, safe and clean methods to generate products with a high load of thermally stable thermochromic VO 2 particles. These procedures are different to standard ones (mainly hydrothermal routes) because they involve the controlled heat treatment of pure vanadium nanoparticles in air at atmospheric pressure inside an open tube.…”

Phase-Engineered VO2 Meta Nanofiber Enables a Metal–Insulator Transition for Bidirectional Thermal Reallocation

“…The metal–insulator transition (MIT) materials with solid–solid phase change offer an elegant solution to overcome the above issues; , they undergo a transformation of crystal structure to achieve thermal reallocation without shifting into isotropic liquid or gas states, − resulting in the beneficial properties of negligible volume expansion, adequate shape-stability, and long phase-change cycle life. , Transition metal oxides, particularly vanadium dioxide (VO 2 ), are the most notable MIT materials due to their phase transition at near room temperature and mutation of optical/electrical performance during phase transition. − Most recently, there has been a certain amount of research into VO 2 , including VO 2 films, VO 2 nanosheets, VO 2 layers, VO 2 nanoparticles, etc . The above two-dimensional architectures and nanostructures possess the characteristics of difficult scalability, high cost, and discontinuity, , thereby restricting their further development and application.…”

“…26,27 Transition metal oxides, particularly vanadium dioxide (VO 2 ), are the most notable MIT materials due to their phase transition at near room temperature and mutation of optical/electrical performance during phase transition. 28−31 Most recently, there has been a certain amount of research into VO 2 , including VO 2 films, 32 VO 2 nanosheets, 33 VO 2 layers, 34 VO 2 nanoparticles, 35 etc. The above two-dimensional architectures and nanostructures possess the characteristics of difficult scalability, high cost, and discontinuity, 36,37 thereby restricting their further development and application.…”