Pale yellow powder, dissolve in water and inorganic acid, soluble in hot alkali, slightly soluble in hydrofluoric acid.Tungsten(VI) oxide, also known as tungsten trioxide or tungstic anhydride, WO3, is a chemical compound containing oxygen and the transition metal tungsten Tungsten oxideoccurs naturally in form of hydrates, which include minerals: tungstite WO3·H2O, meymacite WO3·2H2O and hydrotungstite (of same composition as meymacite, however sometimes written as H2WO4). These minerals are rare to very rare secondary tungsten minerals.
Tungsten trioxide is used for many purposes in everyday life. It is frequently used in industry to manufacture tungstates for x-ray screen phosphors, for fireproofing fabrics and in gas sensors. Due to its rich yellow color, WO3 is also used as a pigment in ceramics and paints. In recent years, tungsten trioxide has been employed in the production of electrochromic windows, or smart windows. These windows are electrically switchable glass that change light transmission properties with an applied voltage. This allows the user to tint their windows, changing the amount of heat or light passing through. Another new use for tungsten is in Dense Inert Metal Explosives, the first notable use of these devices was during the 2008–2009 Israel–Gaza conflict. 2010- AIST reports a quantum yield of 19 % in photocatalytic water splitting with a cesium enhanced tungsten oxide photocatalys.