Optical grade tungsten trioxide is a type of light yellow powder of optical grade (10-^8 orders of magnitude). Its purity can reach 99.99%. The tungsten trioxide becomes dark orange if it is heated and restores its original color if it is cooled.
The tungsten trioxide thin film with uniform surface is prepared by sol-gel method and direct current reactive magnetron sputtering method. The light transmittance and the structure of the film are measured by double beam UV-visible light spectrophotometer and X-ray diffraction. And the effects of annealing temperature on the light transmittance and the morphology of the film are observed. The results are shown as follows:
1. After annealing treatment at high temperature (temperature higher than 300 °C), the light transmittance of the film decreases. And the higher the annealing temperature, the lower the light transmittance.
2. After annealing below 350 °C, the film sample is in amorphous state. And the sample will change from amorphous structure to crystalline structure if it is annealed at the temperature range of 350 ~ 400 °C.
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