Orange tungsten oxide is a compound usually referred to as a non-stoichiometric oxidation state of tungsten oxide with the chemical formula WO3. However, it is orange in color. This orange color originates from defects or impurities in the crystal structure of tungsten oxide, or from the presence of low valence tungsten ions due to partial reduction. Tungsten oxide is usually yellow or green, but under certain conditions (e.g. heat treatment or partial reduction) it can take on an orange, blue or other color.
Orange Tungsten Oxide Specification Sheet
