Iron phosphide is a chemical compound of iron and phosphorus, with a formula of FeP. Its physical appearance is grey, hexagonal needles. Manufacturing of iron phosphide takes place at elevated temperatures, where the elements combine directly. Iron phosphide reacts with moisture and acids producing phosphine (PH3), a toxic and pyrophoric gas. Iron phosphide can be used as a semiconductor. It has use in high power, high frequency applications, such as laser diodes.