Tungsten outer electron configurations is sd46s, thus, five kinds of valence (+ 2, + 3, + 4, + 5 + 6) can present in the compounds. The valence of W in WO3 is highest in tungsten oxide. Usually the oxygen content of WO3 does not meet the strict stoichiometric ratio, it represented in the form of WO3-x.

 

WO3 formula is quite simple, but its physical properties is very complex.The melting point of WO3 reported in literature is 1473 ℃, but in 1100 ℃ WO3 starts sublimation, sublimation heat is 459.8 kJ/mol. Strictly meet the stoichiometric ratio of tungsten trioxide and without any impurities, WO3 should be transparent insulation. The forbidden band width is about 2.9 eV at room temperature.The WO3-x show n type semiconductor behavior, and forbidden band width is 2.4~2.8eV. Due to the phase change of the structure of WO3, with the change of temperature, resistivity of WO3 will appear jump phenomenon, its resistivity is commonly in 0.3~10 Ω·cm.

 

 

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