Diferro phosphide, Fe₂P

Diferro phosphide, Fe₂P, may be obtained by heating finely divided iron with copper phosphide in an electric furnace. On dissolving the residue in nitric acid crystalline needles remain, of density 6.56, and melting at 1290° C. Diferro phosphide may also be obtained by fusing iron and phosphorus together and subsequently separating the more magnetic impurities. It is insoluble in acids, except aqua regia. Fluorine attacks it at red heat. When heated in air it oxidises to a basic ferric phosphate.