Thin film coatings can change the color of the film due to the absorption of external energy. This material is called electrochromic material, and the electrochromic effect of tungsten trioxide film is closely related to its microstructure.
The yellow tungsten oxide, tungsten trioxide, is a typical representative of inorganic electrochromic materials. Its principle is to adjust the light transmittance by changing the size of the current, realizing the dimming from transparent to opaque.
On the WO3 film electrochromic mechanism, the current Faughnan proposed intervalence jump theory, that is, due to the role of the applied electric field, electrons and cationic minerals from both sides of the film were injected into the WO3 at the same time, the electrons were captured by the W atoms to form a localized state, and the metal ions M + reside in this region to form a dark blue tungsten bronze compound Mx WO3, in the presence of different valence states of the W ions in the Mx WO3, the electrons in the vicinity of different valence states of the W ions, the W ions in the vicinity of different valence states. In Mx WO3, there are different valence states of W ions, and the electron jumps between neighboring W atoms of different valence states lead to the color change of WO3 film.
The electrochemical process is shown in the following equation:
WO3 (colorless) +xM+xeMx WO3 (dark blue)
The yellow tungsten oxide electrochromic thin film is prepared by using the electrochromic property of tungsten trioxide and various methods such as physical vapor deposition, chemical vapor deposition and electron beam evaporation method, etc. It has the advantages of low cost, good cyclic reversibility, good optical performance and fast color change, which can be used in smart windows, architectural glass, automotive rearview mirrors and other fields.
The steps for the preparation of ceramic target tungsten trioxide thin film by RF magnetron sputtering method are as follows:
- conductive glass ITO before the use of the substrate to do cleaning, the order of the use of deionized water, alcohol, acetone to ultrasonic vibration machine each vibration 15 minutes to remove surface stains and organic matter;
- Remove the specimen and blow-dry it, and quickly put it into the vacuum chamber to prepare for sputtering;
- After the substrate is put into the vacuum chamber, first pump it to about 3×10-3 by mechanical rotary pump, then pump it to below 2×10-6 by condensing pump for half an hour, and heat the substrate to the experimental temperature, then introduce Ar atmosphere O2 oxygen to be deposited under different oxygen atmospheres, and then treat the target surface before sputtering in order to remove the impurities and oxidized layer, and then adjust the sputtering power to (100W).
Technical specification:
Particle size 30-50nm
Appearance Light yellow powder
Purity of WO3 ≥99.95
Specific surface area, m2/g 10-20
Loss of weight on burning ≤0.05
Packing:
Bulk package: 25Kg/ctn
Sample package: 5Kg/bag
More details of tungsten oxide product, please visit website: tungsten-oxide.com
Please contact CHINATUNGSTEN for inquiry and order of tungsten oxide:
Email: sales@chinatungsten.com
Tel.: 86 592 5129595
