Tantalum pentoxide, also known as tantalum(V) oxide, is the inorganic compound with the formula Ta2O5. It is a white solid that is insoluble in all solvents but is attacked by strong base and hydrofluoric acid. Both orthorhombic and hexagonal phases are known. Ta2O5 is a high refractive index, low absorption (i.e. colourless), inert material, which makes it useful for coatings.
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