Tungsten trioxide is a new type of electrochromic material that is able to reversibly and persistently change its optical properties at an external voltage. Tungsten trioxide is considered as one of the most promising candidates for fabricating energy-saving smart window.

Tungsten oxide nano-urchins are paid much attention due to good electrochromic performance. You know, tungsten oxide as an inorganic electrochromic material has attracted considerable attention as it is promising in applications of electrochromic glass - energy-saving smart glass having high shielding performance to near-infrared rays and high transmittance to visible light.

It has been reported that some experts fabricated nanocrystalline tungsten oxide based NO2 sensor by thin film microfabrication technique. And the sensitivity of this NO2 sensor was at parts per billion (ppb) level.

W18O49 is an important material for fabricating infrared-shielding film, to sufficiently transmit visible rays and shield invisible near-infrared rays. Some experts prepared W18O49 powder by heating a mixture containing a predetermined amount of a tungsten compound at 550 °C in a reductive atmosphere for 1 h, then cooled to room temperature once in an argon atmosphere.