High quality thermochromic VO2 thin films deposited at room temperature by balanced and unbalanced HiPIMS

Doubling of the Phase Transition Temperature of VO2 by Fe Doping

“…Vanadium dioxide (VO 2 ) is a well-known thermochromic material, which undergoes a fully reversible first-order metal–insulator transition (MIT) from a low-temperature monoclinic M1 phase ( P 2 1 / c ) to a high-temperature tetragonal phase ( P 4 2 / mnm ) at around 68 °C. At the structural transition, significant changes in atomic organization are intertwined with changes in the electrical, optical, and magnetic properties, , making VO 2 a promising candidate for switching applications, , but with controversies remaining about the Peierls or Mott origin for the phase transition. − In our own previous studies, considering that the phase transition is well linked to structural origin, geometrical calculations in agreement with experimental studies suggested that the VO 2 phase transition is a consequence of very short atomic shifts mainly associated with a decrease in the level of second-sphere Coulombic interactions . For practical use, various transition temperatures of VO 2 are desired to fulfill the different demands depending on the applications.…”

Recent advances in vanadium pentoxide (V2O5) towards related applications in chromogenics and beyond: fundamentals, progress, and perspectives

“…This is an essential parameter for evaluating the intensity of the color change in a chromogenic device and can be estimated at a specific wavelength or in white light. 15 Although T(l), R(l), and the intensity of absorption A(l) have the relation, T(l) + R(l) + A(l) = 1, the optical contrast was calculated using eqn (7) or (9). Moreover, the optical contrast can also be evaluated from the ratio of T(l) or R(l) between states, as shown in eqn ( 8) or (10).…”

“…5 In addition, chromic properties are also extended to applications, such as thermal control in the IR region, and variable IR/NIR devices. 6,7 As stated earlier, chromogenics corresponds to irreversible/reversible changes in material color and optical characterization caused by a change in the chemical and physical properties due to external stimuli. Among them, electrochromism has attracted considerable attention because of the facile control of the insertion/de-insertion of metal ions and carrier concentration at the applied voltage, allowing control of the optical contrast, switching time, and coloration efficiency.…”

Design and reactive magnetron sputtering of thermochromic coatings

“…[50][51][52] Reactive magnetron sputter deposition with its versatility and the potential of scaling up to large substrate sizes is probably the most important preparation technique of VO 2 -based thermochromic coatings. 7,8,53,54 The previous efforts utilized all main versions of this technique, ranging from frequently used dc sputtering, [2][3][4][5][6][7][8][9][10] rf sputtering, [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] and high-power impulse sputtering (HiPIMS) [30][31][32][33][34][35][36][37][38][39][40][41] to rf-superimposed dc sputtering, 42 inductively coupled plasma assisted sputtering,…”