Crystallization and thermochromism in tungsten oxide films annealed in vacuum

A Temperature-Responsive Copper Molybdate Polymorph Mixture near to Water Boiling Point by a Simple Cryogenic Quenching Route

“…phase transition 15 , which in turn affect the absorption spectrum of the material.Inorganic thermochromic materials have the advantage of better stability and longer lifetime as well as easy and cost-effective preparation over their commonly used organic counterparts. [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] Most of the available inorganic thermochromic metal oxides are reversible (figure 2 and table S1) and cannot be used to continuously and reliably monitor the temperature change over a period because their color changes back to its original color on cooling. 16,17,25 In contrast, irreversible materials are Figure 2.…”

“…and this limits their practical use, which enhances the need for and importance of low transition temperature inorganic thermochromic materials. [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] Ehrenberg et al, in 1997 reported the presence of a new phase in CuMoO4, which is stable below -73 °C. 19 In 1997, Wiesmann et al, reported phase transition from the stable to the phase in single crystal CuMoO4 at atmospheric pressure by cooling at -83 °C or at room temperature by applying pressure (0.2 GPa).…”

“…This behavior may result from a reduction of band gap energies and ligand field on a chromophore cation, , insulating-metallic behavior transitions, and changes in the electronic transition energies corresponding to the extension or compression of the crystal cell, that is, phase transition, which in turn affect the absorption spectrum of the material. Inorganic thermochromic materials have the advantage of better stability and longer lifetime as well as easy and cost-effective preparation over their commonly used organic counterparts. − …”

Chemical composition and crystal structure of tungsten oxide films

“…The effect of thermochromism was also observed in our experiments [6,28,29]. The films with a thickness of 110 ± 5 nm were synthesized on quartz glass by the method of reactive magnetron sputtering using a direct current and undewent the stepwise thermal treatment in the temperature range from 500 to 750°C for 1 h at each step.…”

“…indicates that they are attracting the increasing interest of researchers [1][2][3][4][5][6]. The number of articles on this topic has grown almost by twenty times during the 2000 to 2013 period, and more than 2000 works are devoted to tungsten oxide films.…”