Phosphoric anhydride appears as a white amorphous powder. Corrosive to metals and tissue and moderately toxic Diphosphonate(2-) is a divalent inorganic anion obtained by removal of both protons from diphosphonic acid. It is a phosphorus oxoanion and a divalent inorganic anion. It is a conjugate base of a diphosphonate(1-).

It is mainly used as a desiccant for gases and liquids, a dehydrating agent for organic synthesis, an antistatic agent for polyester resin, and a refining agent for pharmaceuticals and sugar. It is also the parent raw material for the production of high-purity phosphoric acid, phosphates, phosphides and phosphate esters, and can be used in the manufacture of phosphorus pentoxide sol and H‑based aerosols.It is used in the production of optical glass, UV-transmitting glass, heat-insulating glass, microcrystalline glass, opal glass, etc., to improve the dispersion coefficient and UV transmittance of glass.